Leah Gerber is an Associate Professor of ecology at Arizona State University. Her research is motivated by a desire to connect academic pursuits in conservation science to decision tools and effective conservation solutions. This approach includes a solid grounding in natural history and primary data collection, quantitative methods and an appreciation for the interactions between humans and the environment. She is keenly aware of the need for the communication of scientific results to the public and to government and non-governmental agencies. This communication is essential for the translation of scientific results into tenable conservation solutions.
DXS: First, can you give me a quick overview of what your scientific background is and your current connection to science?
LG: I learned about ecology and environmental conservation as an undergraduate and quickly became motivated to do science that impacted the real world of conservation. Learning about the impacts of humans on nature was a wake-up call for me, and inspired me to channel my feeling of concern for the demise of nature in a positive way.
From there, I have walked the tightrope between science and policy. After getting my undergraduate degree in environmental biology, I wanted to do more than just the science. So I enrolled in a masters program at the University of Washington – an interdisciplinary program called Marine Affairs. It was a great experience, but I wanted to have more substance to my science background – I wanted to know how to do the science in addition to how to apply the science.
This compelled me to enter a PhD at the University of Washington, which was largely funded by NOAA. My thesis involved trying to figure out how to make decisions about endangered species – how to determine which were endangered and which were threatened. This was a perfect project given my interest in developing tools to solve problems. After finishing my PhD, I did a postdoc at the National Center for Ecological Analysis and Synthesis (NCEAS) and developed approaches for marine reserve design and endangered species recovery. I was at NCEAS for three years before starting on the tenure track at Arizona State University. I’ve been at ASU for about 10 years now.
A major theme in my work has remained constant – that is, how to use the information we are generating in the natural and social sciences to better manage our natural world. Pre-tenure I focused a lot more on doing the science, publishing in good journals, and hoping that it made its way into good policy. Now that I am midcareer, meaning that I have a good amount of papers and tenure, I am enjoying the opportunity to work with practitioners outside of academia. For instance, I just got off the phone with someone from National Geographic regarding my recent publicationon seafood health and sustainability. In that study, we performed an analysis regarding seafood in the context of health and sustainability, to answer simple questions like, what to order when out to sushi? How do we educate about health benefits and risks? We will be organizing a workshop to help restaurant chains, grocery stores, as well as environmental NGOs identify a path forward in informing consumers about healthy and sustainable seafood choices. As a tenured professor, I feel fortunate to have the opportunity to work at the science-policy interface and to give society some science that is truly applicable.
DXS: It is too bad that you have to wait until you are more established and have tenure to go out and engage with the public, because this type of thing is just so important!
LG: Yes, I agree. There isn’t a clear path in academia when it comes to public engagement. But in recent years I have felt optimistic – the landscape within academia is starting to change, and at ASU this change is noticeable. We have a fabulous president, Michael Crow, who has really transformed ASU from just another state institution to a leader in sustainability. Part of this is the establishment of the Global Institute for Sustainability, and one of Michael Crow’s mantras is “community embeddedness.” He is really on board with this type of thing and I have seen evidence of his commitment trickle down throughout the University. For instance, when I first arrived, I had to justify and explain why I was serving on these federal recovery teams for endangered species. Now I feel that there is no justification needed. Developing solutions is not only so important for society, but should also be a key aspect of what we do at Universities.
DXS: We were introduced by another fantastic science communicator, Liz Neeley, who you met at a communications workshop. Why is it important to take part in this type of training?
LG: I met the Fantastic and Fashionable Liz through the Leopold Leadership Program, offered through the Woods Institute for the Environment at Stanford University. The Leopold Leadership training was the best professional development experience of my career, and has made me a better translator and communicator of science to policy. Pre-Leopold, I had little training in communications, and there I was, in a teaching position where I taught hundreds students. I thought to myself, well, how do I do this? The Leopold experience has solidified my commitment to teaching students about communication and engaging in policy.
One development emerging from this training is a science communication symposium at the AAAS meeting. Elena Bennett and I are giving a talk on overcoming institutional barriers for community engagement, and we will address the issues head on. We put out a survey asking others if they faced institutional barriers, and how they might work to engage more.
DXS: What ways do you express yourself creatively that may not have a single thing to do with science?
LG: I have 2 young kids, a 3yo and a 7yo. Being a mom helps me keep it real - I love that I get to enjoy the awe of discovering the world with my girls. We just got a puppy this weekend and we are having fun dressing her up and painting her nails (only partly joking). Other things that I do that are creative – truthfully, I am uninteresting – I don’t bake bread or go to the opera. I just work and take care of my kids. I practice yoga for my own sanity and also love to work in the garden. Doing these things gives me a reason to pause and step off the treadmill of keeping up with everything.
DXS: Do you find that your scientific background informs the creativity you have with your kids or your yoga practice, even though what you do may not specifically be scientific?
LG: I think there is synergy with my science and my kids and my yoga practice in helping me to accept things and be mindful – but not in any conscious way. For instance, when doing my science, the type A person that I am, I have an inclination to keep pushing, pushing, pushing. My kids and my yoga help me to shift gears and accept that things are going to happen when they happen. I try to let the kids be kids, including the associated chaos, and accept that this is a snapshot in time that they will be little. Now I find joy in that chaos. Having kids and yoga gives me a little more perspective, and the knowledge that things aren’t lined up and neatly placed in a box. It rounds me out.
DXS: Are your kids are major influencers in your career?
LG: My first child, Gabriella, was born just after I submitted my application for tenure – so it was good timing. And I was able to slow down. I quickly realized that I wasn’t able to work a 60+hour week. Before kids, I lived to work. Now, I work to live. I absolutely love my job and I feel so lucky that I have a career that I believe in and that I am actually paid to do it – it’s not just a hobby. But having kids made me chill out a little. If I get a paper rejected, I can let it go instead of lamenting about it for weeks. It has made me healthier. I don’t necessarily know if it has had positive impact on my career – time will tell. While my publication rate may be slightly smaller, I think my work now has different dimensions, and greater depth.
I am still pretty passionate about my work, and my kids know what I do and are proud of it. They share it with their classmates, and take every opportunity to wax poetic about how their mom saves animals in the ocean. They also have a built in conservation effort – my 7YO gets irritated when she can’t find a compost bin, and her new thing is to only fill her cup half way because she will only drink a little bit of water.
DXS: When you decided to have children, did your colleagues view you differently? Did they consider that you were sending your career down the tubes or was it a supportive environment?
LG: I honestly had a really positive experience. I can’t think of any negative sentiments from my colleagues, and they were actually really supportive. For instance, when I was pregnant with my first daughter, ASU did not have a maternity leave policy. Before that, you would have to take sick leave. So my colleague worked within the parameters of the unit to give me maternity leave. And then with my second daughter, our new president had established a maternity policy.
The support of my colleagues at ASU has made me feel loyal to my institution. Normally, I am loyal to people and not institutions, but overall, the support has been fabulous. Of course, with having the kids in each case, I did decline a lot of invitations – some pretty significant ones – but I did not have a desire to drag a newborn to give a talk, especially when I was nursing. And it was hard for me to do this at times, especially given my career driven nature, and I had to learn to accept that there would be other opportunities.
I had to shift it down a notch and realize that the world wasn’t going to freeze over, and that I could shift it back to high gear later. With “mommy brain”, I knew I wasn’t going to be at the top of my game at that point in my life. But I have incredible role models. Most notable is Jane Lubchenco, currently the Director of the National Oceanic and Atmospheric Administration. During the first part of her career, she shared a position with her husband – each did 50% – and they did that on purpose so they’d be able to enjoy having children and effectively take care of them. Now, she is in the National Academy, is having major scientific impacts, and she did it all despite having kids. If she can do it, why cant the rest of us?
DXS: Given your experiences as a researcher, as a mother, and now as a major science communicator, do you feel that your ability to talk to people has evolved?
LG: Absolutely. I think that the Leopold Training Program, which selects 20 academics from North America to participate in retreats to learn how to be better communicate and lead, has re-inspired all who attended. It has recharged our batteries and allowed us to make realizations that doing good science and putting it out there via scientific publication is just not enough. We also have to push it out there and make it available to a broader, more diverse population. As part of the training, we also learned about different thinking styles – super analytical or super emotional – and after I returned, I had my lab group participate in this type of exercise. And now I feel like I can better assess a persons thinking style and adjust the way I communicate accordingly.
DXS: Did you always have the ability to talk to the general public or does having kids help you to better understand some of the nuances associated with science communication?
LG: I think so. In fact, I am thinking back to when I had a paper in Sciencecome out around the time that I had my first child. It got a lot of news coverage and was featured in Time magazine. I thought it was so cool at the time, but looking back on it I realized that have come a long way. I said something to a journalist, who then asked me to translate it into “plain English.” It was a little bit of a jab.
Now, with kids, I can tell you a lot more about my research and can better see the broader impact. Talking to them helps me to do that. Here is a conversation about my research with my daughter:
L: Mama is working on figuring out how to help the whales that people like to eat. It’s a big problem because some people like to eat whales and some like to see them swimming in the ocean.
G: What we have to do is let the people eat the whales in the ocean, and buy some whales from the pet store to put back in the ocean. How much do whales cost?
L: Good idea. But you can’t buy whales at the store. They are too big. And if we take them all out of the ocean there will be none left.
G: Well instead we should ask the people to eat bad things like sharks.
L: Another good idea. But if we take sharks out there will be no predators to eat the big fish. And the whole ecosystem would collapse.=
G: Well then the people should eat other things like fish instead of whales. They should buy a fishing pole and catch a fish and eat those instead of whales.
L: What about chicken, shouldn’t people just eat chicken?
G: Mama, we can’t kill chickens. Chickens are nicer than fish, so that’s why we have to eat fish.
L: What about just eating vegetables?
G: Oh mama, some people are meat-eaters. And there are no more dinosaurs. They all got extinct. They should have saved some of the dinosaur meat in the freezer for the meat-eaters. When the dinosaurs come back, there will be enough meat to eat and people won’t want to eat whales.
The simplicity of taking myself out of my research bubble and engaging with a creative (and nonlinear?) 7YO has taught me how to be a better communicator – with the media, with my students, and with the general population.
DXS: Do you think these efforts in science communication are helping to shift other peoples perspectives about who a scientist actually is? For instance, are we changing the old crazy haired white guy stereotype?
LG: Well, I hope so. A couple of examples – again, as a mom, one of my daughters a Girl Scout and I get to help with the troop. One of the themes was to teach about environmental and conservations awareness. We did this Crayola molding experiment where we put our fingers into cold water. We then did the same thing except we put modeling clay over our fingers before putting them into the cold water and to learn about adaptations to extreme environments. Also, we play games where they simulate fishing – what if there is plastic? What happens to you if you eat that? My hope is that this shows these young girls that science is both interesting and fun.
Another thing that just happened today is that I was contacted by Martha Stewart’s office, and it seems that some of my research results will be featured in the October issue of Martha Stewart Living. The message here is that I happen to care about the ocean, but I also love sushi. I also I care about health. I am not just a nerd in a lab coat. I am a mom, I do yoga, I have wonderful friends, and here is the kind of science that I do. It seems to me that it is better to connect with others when I can give them something that is relevant to their lives instead of a more abstract ecological theory.
DXS: If you had something you could say to the younger you about getting on your chosen career path, what would you say?
LG: I feel like I have been very effective at figuring out how to get from point A to point B, but less successful at savoring the process. I think that I’d tell myself to make time to celebrate the small victories. I have also learned to identify what kind of research is most exciting, and I would tell myself to say “no” to everything that is only moderately interesting. I tell my grad students that if you don’t dive in head first, you won’t ever know. So why just not give it a try! And if it doesn’t work, move on. Also, if something isn’t making you happy, change! Academia isn’t for everyone, and there is a lot more to life than science.
The four basic categories of molecules for building life are carbohydrates, lipids, proteins, and nucleic acids.
Carbohydrates serve many purposes, from energy to structure to chemical communication, as monomers or polymers.
Lipids, which are hydrophobic, also have different purposes, including energy storage, structure, and signaling.
Proteins, made of amino acids in up to four structural levels, are involved in just about every process of life.
The nucleic acids DNA and RNA consist of four nucleotide building blocks, and each has different purposes.
The longer version
Life is so diverse and unwieldy, it may surprise you to learn that we can break it down into four basic categories of molecules. Possibly even more implausible is the fact that two of these categories of large molecules themselves break down into a surprisingly small number of building blocks. The proteins that make up all of the living things on this planet and ensure their appropriate structure and smooth function consist of only 20 different kinds of building blocks. Nucleic acids, specifically DNA, are even more basic: only four different kinds of molecules provide the materials to build the countless different genetic codes that translate into all the different walking, swimming, crawling, oozing, and/or photosynthesizing organisms that populate the third rock from the Sun.
Big Molecules with Small Building Blocks
The functional groups, assembled into building blocks on backbones of carbon atoms, can be bonded together to yield large molecules that we classify into four basic categories. These molecules, in many different permutations, are the basis for the diversity that we see among living things. They can consist of thousands of atoms, but only a handful of different kinds of atoms form them. It’s like building apartment buildings using a small selection of different materials: bricks, mortar, iron, glass, and wood. Arranged in different ways, these few materials can yield a huge variety of structures.
We encountered functional groups and the SPHONC in Chapter 3. These components form the four categories of molecules of life. These Big Four biological molecules are carbohydrates, lipids, proteins, and nucleic acids. They can have many roles, from giving an organism structure to being involved in one of the millions of processes of living. Let’s meet each category individually and discover the basic roles of each in the structure and function of life.
You have met carbohydrates before, whether you know it or not. We refer to them casually as “sugars,” molecules made of carbon, hydrogen, and oxygen. A sugar molecule has a carbon backbone, usually five or six carbons in the ones we’ll discuss here, but it can be as few as three. Sugar molecules can link together in pairs or in chains or branching “trees,” either for structure or energy storage.
When you look on a nutrition label, you’ll see reference to “sugars.” That term includes carbohydrates that provide energy, which we get from breaking the chemical bonds in a sugar called glucose. The “sugars” on a nutrition label also include those that give structure to a plant, which we call fiber. Both are important nutrients for people.
Sugars serve many purposes. They give crunch to the cell walls of a plant or the exoskeleton of a beetle and chemical energy to the marathon runner. When attached to other molecules, like proteins or fats, they aid in communication between cells. But before we get any further into their uses, let’s talk structure.
The sugars we encounter most in basic biology have their five or six carbons linked together in a ring. There’s no need to dive deep into organic chemistry, but there are a couple of essential things to know to interpret the standard representations of these molecules.
Check out the sugars depicted in the figure. The top-left molecule, glucose, has six carbons, which have been numbered. The sugar to its right is the same glucose, with all but one “C” removed. The other five carbons are still there but are inferred using the conventions of organic chemistry: Anywhere there is a corner, there’s a carbon unless otherwise indicated. It might be a good exercise for you to add in a “C” over each corner so that you gain a good understanding of this convention. You should end up adding in five carbon symbols; the sixth is already given because that is conventionally included when it occurs outside of the ring.
On the left is a glucose with all of its carbons indicated. They’re also numbered, which is important to understand now for information that comes later. On the right is the same molecule, glucose, without the carbons indicated (except for the sixth one). Wherever there is a corner, there is a carbon, unless otherwise indicated (as with the oxygen). On the bottom left is ribose, the sugar found in RNA. The sugar on the bottom right is deoxyribose. Note that at carbon 2 (*), the ribose and deoxyribose differ by a single oxygen.
The lower left sugar in the figure is a ribose. In this depiction, the carbons, except the one outside of the ring, have not been drawn in, and they are not numbered. This is the standard way sugars are presented in texts. Can you tell how many carbons there are in this sugar? Count the corners and don’t forget the one that’s already indicated!
If you said “five,” you are right. Ribose is a pentose (pent = five) and happens to be the sugar present in ribonucleic acid, or RNA. Think to yourself what the sugar might be in deoxyribonucleic acid, or DNA. If you thought, deoxyribose, you’d be right.
The fourth sugar given in the figure is a deoxyribose. In organic chemistry, it’s not enough to know that corners indicate carbons. Each carbon also has a specific number, which becomes important in discussions of nucleic acids. Luckily, we get to keep our carbon counting pretty simple in basic biology. To count carbons, you start with the carbon to the right of the non-carbon corner of the molecule. The deoxyribose or ribose always looks to me like a little cupcake with a cherry on top. The “cherry” is an oxygen. To the right of that oxygen, we start counting carbons, so that corner to the right of the “cherry” is the first carbon. Now, keep counting. Here’s a little test: What is hanging down from carbon 2 of the deoxyribose?
If you said a hydrogen (H), you are right! Now, compare the deoxyribose to the ribose. Do you see the difference in what hangs off of the carbon 2 of each sugar? You’ll see that the carbon 2 of ribose has an –OH, rather than an H. The reason the deoxyribose is called that is because the O on the second carbon of the ribose has been removed, leaving a “deoxyed” ribose. This tiny distinction between the sugars used in DNA and RNA is significant enough in biology that we use it to distinguish the two nucleic acids.
In fact, these subtle differences in sugars mean big differences for many biological molecules. Below, you’ll find a couple of ways that apparently small changes in a sugar molecule can mean big changes in what it does. These little changes make the difference between a delicious sugar cookie and the crunchy exoskeleton of a dung beetle.
Sugar and Fuel
A marathon runner keeps fuel on hand in the form of “carbs,” or sugars. These fuels provide the marathoner’s straining body with the energy it needs to keep the muscles pumping. When we take in sugar like this, it often comes in the form of glucose molecules attached together in a polymer called starch. We are especially equipped to start breaking off individual glucose molecules the minute we start chewing on a starch.
Double X Extra: A monomer is a building block (mono = one) and a polymer is a chain of monomers. With a few dozen monomers or building blocks, we get millions of different polymers. That may sound nutty until you think of the infinity of values that can be built using only the numbers 0 through 9 as building blocks or the intricate programming that is done using only a binary code of zeros and ones in different combinations.
Our bodies then can rapidly take the single molecules, or monomers, into cells and crack open the chemical bonds to transform the energy for use. The bonds of a sugar are packed with chemical energy that we capture to build a different kind of energy-containing molecule that our muscles access easily. Most species rely on this process of capturing energy from sugars and transforming it for specific purposes.
Polysaccharides: Fuel and Form
Plants use the Sun’s energy to make their own glucose, and starch is actually a plant’s way of storing up that sugar. Potatoes, for example, are quite good at packing away tons of glucose molecules and are known to dieticians as a “starchy” vegetable. The glucose molecules in starch are packed fairly closely together. A string of sugar molecules bonded together through dehydration synthesis, as they are in starch, is a polymer called a polysaccharide (poly = many; saccharide = sugar). When the monomers of the polysaccharide are released, as when our bodies break them up, the reaction that releases them is called hydrolysis.
Double X Extra: The specific reaction that hooks one monomer to another in a covalent bond is called dehydration synthesis because in making the bond–synthesizing the larger molecule–a molecule of water is removed (dehydration). The reverse is hydrolysis (hydro = water; lysis = breaking), which breaks the covalent bond by the addition of a molecule of water.
Although plants make their own glucose and animals acquire it by eating the plants, animals can also package away the glucose they eat for later use. Animals, including humans, store glucose in a polysaccharide called glycogen, which is more branched than starch. In us, we build this energy reserve primarily in the liver and access it when our glucose levels drop.
Whether starch or glycogen, the glucose molecules that are stored are bonded together so that all of the molecules are oriented the same way. If you view the sixth carbon of the glucose to be a “carbon flag,” you’ll see in the figure that all of the glucose molecules in starch are oriented with their carbon flags on the upper left.
The orientation of monomers of glucose in polysaccharides can make a big difference in the use of the polymer. The glucoses in the molecule on the top are all oriented “up” and form starch. The glucoses in the molecule on the bottom alternate orientation to form cellulose, which is quite different in its function from starch.
Storing up sugars for fuel and using them as fuel isn’t the end of the uses of sugar. In fact, sugars serve as structural molecules in a huge variety of organisms, including fungi, bacteria, plants, and insects.
The primary structural role of a sugar is as a component of the cell wall, giving the organism support against gravity. In plants, the familiar old glucose molecule serves as one building block of the plant cell wall, but with a catch: The molecules are oriented in an alternating up-down fashion. The resulting structural sugar is called cellulose.
That simple difference in orientation means the difference between a polysaccharide as fuel for us and a polysaccharide as structure. Insects take it step further with the polysaccharide that makes up their exoskeleton, or outer shell. Once again, the building block is glucose, arranged as it is in cellulose, in an alternating conformation. But in insects, each glucose has a little extra added on, a chemical group called an N-acetyl group. This addition of a single functional group alters the use of cellulose and turns it into a structural molecule that gives bugs that special crunchy sound when you accidentally…ahem…step on them.
These variations on the simple theme of a basic carbon-ring-as-building-block occur again and again in biological systems. In addition to serving roles in structure and as fuel, sugars also play a role in function. The attachment of subtly different sugar molecules to a protein or a lipid is one way cells communicate chemically with one another in refined, regulated interactions. It’s as though the cells talk with each other using a specialized, sugar-based vocabulary. Typically, cells display these sugary messages to the outside world, making them available to other cells that can recognize the molecular language.
Lipids: The Fatty Trifecta
Starch makes for good, accessible fuel, something that we immediately attack chemically and break up for quick energy. But fats are energy that we are supposed to bank away for a good long time and break out in times of deprivation. Like sugars, fats serve several purposes, including as a dense source of energy and as a universal structural component of cell membranes everywhere.
Fats: the Good, the Bad, the Neutral
Turn again to a nutrition label, and you’ll see a few references to fats, also known as lipids. (Fats are slightly less confusing that sugars in that they have only two names.) The label may break down fats into categories, including trans fats, saturated fats, unsaturated fats, and cholesterol. You may have learned that trans fats are “bad” and that there is good cholesterol and bad cholesterol, but what does it all mean?
Let’s start with what we mean when we say saturated fat. The question is, saturated with what? There is a specific kind of dietary fat call the triglyceride. As its name implies, it has a structural motif in which something is repeated three times. That something is a chain of carbons and hydrogens, hanging off in triplicate from a head made of glycerol, as the figure shows. Those three carbon-hydrogen chains, or fatty acids, are the “tri” in a triglyceride. Chains like this can be many carbons long.
Double X Extra: We call a fatty acid a fatty acid because it’s got a carboxylic acid attached to a fatty tail. A triglyceride consists of three of these fatty acids attached to a molecule called glycerol. Our dietary fat primarily consists of these triglycerides.
Triglycerides come in several forms. You may recall that carbon can form several different kinds of bonds, including single bonds, as with hydrogen, and double bonds, as with itself. A chain of carbon and hydrogens can have every single available carbon bond taken by a hydrogen in single covalent bond. This scenario of hydrogen saturation yields a saturated fat. The fat is saturated to its fullest with every covalent bond taken by hydrogens single bonded to the carbons.
Saturated fats have predictable characteristics. They lie flat easily and stick to each other, meaning that at room temperature, they form a dense solid. You will realize this if you find a little bit of fat on you to pinch. Does it feel pretty solid? That’s because animal fat is saturated fat. The fat on a steak is also solid at room temperature, and in fact, it takes a pretty high heat to loosen it up enough to become liquid. Animals are not the only organisms that produce saturated fat–avocados and coconuts also are known for their saturated fat content.
The top graphic above depicts a triglyceride with the glycerol, acid, and three hydrocarbon tails. The tails of this saturated fat, with every possible hydrogen space occupied, lie comparatively flat on one another, and this kind of fat is solid at room temperature. The fat on the bottom, however, is unsaturated, with bends or kinks wherever two carbons have double bonded, booting a couple of hydrogens and making this fat unsaturated, or lacking some hydrogens. Because of the space between the bumps, this fat is probably not solid at room temperature, but liquid.
You can probably now guess what an unsaturated fat is–one that has one or more hydrogens missing. Instead of single bonding with hydrogens at every available space, two or more carbons in an unsaturated fat chain will form a double bond with carbon, leaving no space for a hydrogen. Because some carbons in the chain share two pairs of electrons, they physically draw closer to one another than they do in a single bond. This tighter bonding result in a “kink” in the fatty acid chain.
In a fat with these kinks, the three fatty acids don’t lie as densely packed with each other as they do in a saturated fat. The kinks leave spaces between them. Thus, unsaturated fats are less dense than saturated fats and often will be liquid at room temperature. A good example of a liquid unsaturated fat at room temperature is canola oil.
A few decades ago, food scientists discovered that unsaturated fats could be resaturated or hydrogenated to behave more like saturated fats and have a longer shelf life. The process of hydrogenation–adding in hydrogens–yields trans fat. This kind of processed fat is now frowned upon and is being removed from many foods because of its associations with adverse health effects. If you check a food label and it lists among the ingredients “partially hydrogenated” oils, that can mean that the food contains trans fat.
Double X Extra: A triglyceride can have up to three different fatty acids attached to it. Canola oil, for example, consists primarily of oleic acid, linoleic acid, and linolenic acid, all of which are unsaturated fatty acids with 18 carbons in their chains.
Why do we take in fat anyway? Fat is a necessary nutrient for everything from our nervous systems to our circulatory health. It also, under appropriate conditions, is an excellent way to store up densely packaged energy for the times when stores are running low. We really can’t live very well without it.
Phospholipids: An Abundant Fat
You may have heard that oil and water don’t mix, and indeed, it is something you can observe for yourself. Drop a pat of butter–pure saturated fat–into a bowl of water and watch it just sit there. Even if you try mixing it with a spoon, it will just sit there. Now, drop a spoon of salt into the water and stir it a bit. The salt seems to vanish. You’ve just illustrated the difference between a water-fearing (hydrophobic) and a water-loving (hydrophilic) substance.
Generally speaking, compounds that have an unequal sharing of electrons (like ions or anything with a covalent bond between oxygen and hydrogen or nitrogen and hydrogen) will be hydrophilic. The reason is that a charge or an unequal electron sharing gives the molecule polarity that allows it to interact with water through hydrogen bonds. A fat, however, consists largely of hydrogen and carbon in those long chains. Carbon and hydrogen have roughly equivalent electronegativities, and their electron-sharing relationship is relatively nonpolar. Fat, lacking in polarity, doesn’t interact with water. As the butter demonstrated, it just sits there.
There is one exception to that little maxim about fat and water, and that exception is the phospholipid. This lipid has a special structure that makes it just right for the job it does: forming the membranes of cells. A phospholipid consists of a polar phosphate head–P and O don’t share equally–and a couple of nonpolar hydrocarbon tails, as the figure shows. If you look at the figure, you’ll see that one of the two tails has a little kick in it, thanks to a double bond between the two carbons there.
Phospholipids form a double layer and are the major structural components of cell membranes. Their bend, or kick, in one of the hydrocarbon tails helps ensure fluidity of the cell membrane. The molecules are bipolar, with hydrophilic heads for interacting with the internal and external watery environments of the cell and hydrophobic tails that help cell membranes behave as general security guards.
The kick and the bipolar (hydrophobic and hydrophilic) nature of the phospholipid make it the perfect molecule for building a cell membrane. A cell needs a watery outside to survive. It also needs a watery inside to survive. Thus, it must face the inside and outside worlds with something that interacts well with water. But it also must protect itself against unwanted intruders, providing a barrier that keeps unwanted things out and keeps necessary molecules in.
Phospholipids achieve it all. They assemble into a double layer around a cell but orient to allow interaction with the watery external and internal environments. On the layer facing the inside of the cell, the phospholipids orient their polar, hydrophilic heads to the watery inner environment and their tails away from it. On the layer to the outside of the cell, they do the same.
As the figure shows, the result is a double layer of phospholipids with each layer facing a polar, hydrophilic head to the watery environments. The tails of each layer face one another. They form a hydrophobic, fatty moat around a cell that serves as a general gatekeeper, much in the way that your skin does for you. Charged particles cannot simply slip across this fatty moat because they can’t interact with it. And to keep the fat fluid, one tail of each phospholipid has that little kick, giving the cell membrane a fluid, liquidy flow and keeping it from being solid and unforgiving at temperatures in which cells thrive.
Steroids: Here to Pump You Up?
Our final molecule in the lipid fatty trifecta is cholesterol. As you may have heard, there are a few different kinds of cholesterol, some of which we consider to be “good” and some of which is “bad.” The good cholesterol, high-density lipoprotein, or HDL, in part helps us out because it removes the bad cholesterol, low-density lipoprotein or LDL, from our blood. The presence of LDL is associated with inflammation of the lining of the blood vessels, which can lead to a variety of health problems.
But cholesterol has some other reasons for existing. One of its roles is in the maintenance of cell membrane fluidity. Cholesterol is inserted throughout the lipid bilayer and serves as a block to the fatty tails that might otherwise stick together and become a bit too solid.
Cholesterol’s other starring role as a lipid is as the starting molecule for a class of hormones we called steroids or steroid hormones. With a few snips here and additions there, cholesterol can be changed into the steroid hormones progesterone, testosterone, or estrogen. These molecules look quite similar, but they play very different roles in organisms. Testosterone, for example, generally masculinizes vertebrates (animals with backbones), while progesterone and estrogen play a role in regulating the ovulatory cycle.
Double X Extra: A hormone is a blood-borne signaling molecule. It can be lipid based, like testosterone, or short protein, like insulin.
As you progress through learning biology, one thing will become more and more clear: Most cells function primarily as protein factories. It may surprise you to learn that proteins, which we often talk about in terms of food intake, are the fundamental molecule of many of life’s processes. Enzymes, for example, form a single broad category of proteins, but there are millions of them, each one governing a small step in the molecular pathways that are required for living.
Levels of Structure
Amino acids are the building blocks of proteins. A few amino acids strung together is called a peptide, while many many peptides linked together form a polypeptide. When many amino acids strung together interact with each other to form a properly folded molecule, we call that molecule a protein.
For a string of amino acids to ultimately fold up into an active protein, they must first be assembled in the correct order. The code for their assembly lies in the DNA, but once that code has been read and the amino acid chain built, we call that simple, unfolded chain the primary structure of the protein.
This chain can consist of hundreds of amino acids that interact all along the sequence. Some amino acids are hydrophobic and some are hydrophilic. In this context, like interacts best with like, so the hydrophobic amino acids will interact with one another, and the hydrophilic amino acids will interact together. As these contacts occur along the string of molecules, different conformations will arise in different parts of the chain. We call these different conformations along the amino acid chain the protein’s secondary structure.
Once those interactions have occurred, the protein can fold into its final, or tertiary structure and be ready to serve as an active participant in cellular processes. To achieve the tertiary structure, the amino acid chain’s secondary interactions must usually be ongoing, and the pH, temperature, and salt balance must be just right to facilitate the folding. This tertiary folding takes place through interactions of the secondary structures along the different parts of the amino acid chain.
The final product is a properly folded protein. If we could see it with the naked eye, it might look a lot like a wadded up string of pearls, but that “wadded up” look is misleading. Protein folding is a carefully regulated process that is determined at its core by the amino acids in the chain: their hydrophobicity and hydrophilicity and how they interact together.
In many instances, however, a complete protein consists of more than one amino acid chain, and the complete protein has two or more interacting strings of amino acids. A good example is hemoglobin in red blood cells. Its job is to grab oxygen and deliver it to the body’s tissues. A complete hemoglobin protein consists of four separate amino acid chains all properly folded into their tertiary structures and interacting as a single unit. In cases like this involving two or more interacting amino acid chains, we say that the final protein has a quaternary structure. Some proteins can consist of as many as a dozen interacting chains, behaving as a single protein unit.
A Plethora of Purposes
What does a protein do? Let us count the ways. Really, that’s almost impossible because proteins do just about everything. Some of them tag things. Some of them destroy things. Some of them protect. Some mark cells as “self.” Some serve as structural materials, while others are highways or motors. They aid in communication, they operate as signaling molecules, they transfer molecules and cut them up, they interact with each other in complex, interrelated pathways to build things up and break things down. They regulate genes and package DNA, and they regulate and package each other.
As described above, proteins are the final folded arrangement of a string of amino acids. One way we obtain these building blocks for the millions of proteins our bodies make is through our diet. You may hear about foods that are high in protein or people eating high-protein diets to build muscle. When we take in those proteins, we can break them apart and use the amino acids that make them up to build proteins of our own.
How does a cell know which proteins to make? It has a code for building them, one that is especially guarded in a cellular vault in our cells called the nucleus. This code is deoxyribonucleic acid, or DNA. The cell makes a copy of this code and send it out to specialized structures that read it and build proteins based on what they read. As with any code, a typo–a mutation–can result in a message that doesn’t make as much sense. When the code gets changed, sometimes, the protein that the cell builds using that code will be changed, too.
Biohazard!The names associated with nucleic acids can be confusing because they all start with nucle-. It may seem obvious or easy now, but a brain freeze on a test could mix you up. You need to fix in your mind that the shorter term (10 letters, four syllables), nucleotide, refers to the smaller molecule, the three-part building block. The longer term (12 characters, including the space, and five syllables), nucleic acid, which is inherent in the names DNA and RNA, designates the big, long molecule.
DNA vs. RNA: A Matter of Structure
DNA and its nucleic acid cousin, ribonucleic acid, or RNA, are both made of the same kinds of building blocks. These building blocks are called nucleotides. Each nucleotide consists of three parts: a sugar (ribose for RNA and deoxyribose for DNA), a phosphate, and a nitrogenous base. In DNA, every nucleotide has identical sugars and phosphates, and in RNA, the sugar and phosphate are also the same for every nucleotide.
So what’s different? The nitrogenous bases. DNA has a set of four to use as its coding alphabet. These are the purines, adenine and guanine, and the pyrimidines, thymine and cytosine. The nucleotides are abbreviated by their initial letters as A, G, T, and C. From variations in the arrangement and number of these four molecules, all of the diversity of life arises. Just four different types of the nucleotide building blocks, and we have you, bacteria, wombats, and blue whales.
RNA is also basic at its core, consisting of only four different nucleotides. In fact, it uses three of the same nitrogenous bases as DNA–A, G, and C–but it substitutes a base called uracil (U) where DNA uses thymine. Uracil is a pyrimidine.
DNA vs. RNA: Function Wars
An interesting thing about the nitrogenous bases of the nucleotides is that they pair with each other, using hydrogen bonds, in a predictable way. An adenine will almost always bond with a thymine in DNA or a uracil in RNA, and cytosine and guanine will almost always bond with each other. This pairing capacity allows the cell to use a sequence of DNA and build either a new DNA sequence, using the old one as a template, or build an RNA sequence to make a copy of the DNA.
These two different uses of A-T/U and C-G base pairing serve two different purposes. DNA is copied into DNA usually when a cell is preparing to divide and needs two complete sets of DNA for the new cells. DNA is copied into RNA when the cell needs to send the code out of the vault so proteins can be built. The DNA stays safely where it belongs.
RNA is really a nucleic acid jack-of-all-trades. It not only serves as the copy of the DNA but also is the main component of the two types of cellular workers that read that copy and build proteins from it. At one point in this process, the three types of RNA come together in protein assembly to make sure the job is done right.
A conservation scientist walks into a [sushi] bar…
You’ve probably heard that eating a diet including fish, especially fatty fish, is good for us. Fish can be a source of high quality, lean protein, and also provide heart-healthy omega-3 fatty acids. However, there are risks associated with eating some types of fish. For instance, fish that are at the top of the food chain or have a long lifespan (or both!) can accumulate high levels of mercury or chemicals called polychlorinated biphenyls (PCBs). Exposure to high amounts of these compounds could be particularly harmful for pregnant/nursing women or young children.
On the other hand, there is the issue of sustainability. We are seeing a wide-scale collapse of many marine fish populations, which is primarily the result of overfishing. While there are conservation efforts in place to help consumers make eco-friendly choices, it is not clear if raising consumer awareness is impacting fishing or marine farming practices. Furthermore, many consumers will choose fish based on their nutritional value and safety without really considering ecological consequences.
In an attempt to better educate consumers on both nutrition andsustainability with regard to making the best seafood choices, Leah Gerber, professor of Ecology, Evolution and Environmental Science at Arizona State University, has evaluated current fish “eco-ranking” schemes. In a study recently published (PDF) in Frontiers in Ecology and the Environment, Dr. Gerber provides a model that quantifies both the health benefits and sustainability level of individual fish species.
Interestingly, her group found that fish with the highest health benefits, determined by omega-3 fatty acid content, generally had low mercury levels. Similarly, fish that are unsustainable – meaning that fishing threatens their existence — tended to have higher levels of mercury, and lower omega-3 fatty acid amounts. Basically, fish populations that are not threatened by overfishing are generally heart healthy and have low mercury. A win-win!
The novel thing about this study is that it is the first to consider multiple types of sustainability rankings as well as health impacts, and Dr. Gerber is taking her message to the streets. It is her hope that she and her colleagues will be able to develop tools so that consumers can easily make seafood choices that are both good for you and good for the environment.
But the coolest thing about this study is that Dr. Gerber is not a ‘fisheries person’, per se. However, her passion for learning about human impact on the natural environment combined with her love of sushi prompted a closer look at the fishing industries and how to make good choices when it comes to seafood.
This is an excellent example of how a scientist is applying her knowledge to promote science in one of its most relatable forms –- eating! I mean, we all have to eat, and it is particularly awesome when we can do so in the most educated way possible. Kudos to Dr. Gerber for taking this on since we all benefit from knowing.
The opinions expressed in this article neither necessarily reflect nor conflict with those of the DXS editorial team.
I finished assembling the requested cheddar cheese and cracker sandwiches and made sure to follow the precise directions for filling the sippy cups: half apple juice, half water, one ice cube, and a slice of lemon (don’t ask, my kids are high maintenance). Saturday afternoon was upon us and it was clear that we all needed a little downtime. So I set the girls up for a picnic on the family room floor, engaged Netflix, and laid out their snack. After a few minutes of getting comfy, calmness decided to pay us a visit. This was my carpe diem moment.
The perennial mint plant, known in my family as “El Jardin de Mojito.”
The weather could not have been more pleasant, and with the girls under the dear care of my best pal Pingu, I stepped out, barefooted, onto the deck. The sun caressed my cheeks. The wind whispered into my ear. The garden’s cologne was a reminder of my desire. Summer was seducing me and I did not could not resist.
I scanned the world before me, seamlessly moving my gaze from tree to tree, bush to bush, bird to bird, letting each thought morph into the next. I noticed the fluffy marshmallow clouds floating overhead and the sounds of a lawn mower humming in the distance. Then, at eleven o’clock, I caught a glimpse of the mint garden. The free flowing thoughts came to a screeching halt and my mind could focus on one thing and one thing only: Mojitos.
Belonging to the Lamiaceae family along with other aromatic herbs such as basil, oregano, and sage, mint has a tendency to spread rapidly and without care for the plants around it. But for us, this wasn’t an issue. Despite the vast culinary applications for this bountiful botanical, it is the quintessential ingredient for our favorite summer beverage, and so we’ve aligned ourselves with “the more the merrier” philosophy. After all, Greek mythology has dubbed mint as the “herb of hospitality” and what says “welcome to mi casa” more than the delicate sweetness of a cold mojito?
I didn’t bother to grab the scissors and made sure I followed the most direct route toward the mint patch. As I went to grab a large stalk, I noticed a little critter hanging out on one of the leaves. I lessened my grasp and began to examine the mint garden a bit more closely. It appeared to be a micro-ecosystem, bustling with tiny life forms.
Not wanting to miss a photographic opportunity, I ran back in, peeked in at the girls to make sure they were still there, and grabbed my camera (the good one). The snails were everywhere! My first reaction was “you best not be messing with the mojito garden!” But, upon closer inspection, these slow-moving, shelled cylinders of slime might be something more interesting, at least from a biological perspective.
Birds eye view of the European Amber Land Snail.
I knew that snails were mollusks, similar to clams and oysters, and that they could be further classified as gastropods, or “stomach foot” (to us, it looks like they are crawling on their bellies). But, I was having a hard time identifying the species to which these snails belonged, and that was probably because I was limiting my search to native species in NY State.
Frustrated, I turned to Ken Hotopp, conservation biologist and director of the environmental consulting company, Appalachian Conservation Biology. Ken informed me that these snails were amber land snails of the Succinea putris variety, which are native to eastern European countries and Great Britain, and further classified them as an invasive species.
Fred and Ethel, roaming the mint garden. Take a look at the “belly foot.”
When a species is classified as “invasive,” it typically means that they have high reproductive rates, can easily spread, and can quickly adapt to their new environment (a phenomenon called phenotypic plasticity). If these criteria are met, the invasive species can outcompete many of the indigenous species for resources and cause issues for the native habitat.
These snails probably made their way to the new world by hitching a ride on humans and despite the negative connotation associated with being an “invasive species,” it really isn’t their fault. They are just doing what they are biologically programmed to do: survive and pass on their gene pool to the next generation.
Regardless of origin, these snails looked beautiful to me. I love spiraling pattern at the rear of their calcium carbonate shells, and the way their tentacles, with eyes at the tip, scan their environment. It is really cool to watch the rhythmic motions of the foot, which can probably be plotted as a sine wave function in super slow motion.
Close up! Notice the patterns on the calcium carbonate shell, and the black eyes at the tip of the tentacles.
Realizing that time was of the essence (Pingu is effective for only so long), I zoomed out and started looking around for the best leaves to pluck. I said hello to the grasshopper that was probably banking on its green camouflage to keep it safe from predators, and took at look at the brilliant yellow flowers living atop the mint garden canopy. With the prize in hand, I ran into the kitchen, grabbed the simple syrup from the fridge (we always have some on hand), and began to make my mojito.
Within a few minutes, the finished product was in hand. But, alas, it would have to wait for I was being beckoned by the girls with the golden locks. I suppose one more episode of Pingu wouldn’t hurt.
On the second Sunday in May in the United States, mothers reign supreme, receiving tributes of breakfast in bed, hand-made cards, flowers, and obligatory long-distance phone calls. Meanwhile, for the rest of the animal kingdom, it’s just another day: eat, hunt, mate, birth, nest, migrate, defend, and rest.
Some go it alone, but others—like spotted hyenas and bison—live in groups with complex social structures, and moms are at the top, year-round. In a matriarchy, females hold central roles of leadership and power. This might sound like a nice change of pace for some of us, but most anthropologists now agree that there have likely been no true matriarchal human societies (in spite of popular books like The Chalice and the Blade). Instead, matriarchies are more likely to be found in the rest of the animal kingdom, from meerkats to mammoths. Here are a few examples:
The Queen, surrounded by her supportive workers.
Honey bees: Bee colonies are giant matriarchal societies ruled by a single queen—quite literally the “queen mum.” Her offspring (as many as 25,000 at a time) make up the entire clan of female workers and male drones. The queen spends her life tended to by her worker daughters. These workers have underdeveloped reproductive systems, so the queen is the only female in the hive who gets to mate. The females do the work of the hive and tend to the queen while the male drones laze about until it’s time to mate with the queen. This setup might sound appealing at first, but it comes with a couple of important caveats. The Queen only mates once in her lifetime with a select handful of drones who were bred for that sole purpose (assuming they weren’t pushed out or killed by their worker sisters during tough times, when freeloading is less tolerated). During a series of nuptial flights, the queen gets all the sperm she’ll ever need for an entire lifetime—as many as five million individuals. She uses this sperm for to around 2500 eggs a day, which are tended to by her sterile daughters while she dines on royal jelly. The males get no reward for their service, but instead perish shortly after depositing their sperm, the unfortunate victims of an acute case of exploded abdomen.
Meerkats: Meerkat societies are highly structured, with a complex ranking system based on dominance. If you want to get ahead in the meerkat world, perfect the art of chin swiping and hip checking, practiced on those lower down the totem pole while someone more powerful than you is looking the other way. Being on top has its rewards; alpha female meerkats are the only ones who get to mate in meerkat town. A matriarch chooses her partner, who becomes the dominant (and only mating) male. Males initiate copulation by ritually grooming the female until she submits. If the matriarch tires of her partner, he’s quickly deposed by beta males who are more than eager to earn a chance at mating. Alpha females make all the decisions in the group: where to sleep, where to burrow, when to go outside, when to forage. Like bees, meerkat females are typically mother to all the pups in the group (females typically kill pups born of unsanctioned unions). In addition to being free to engage in mating, being a matriarchal meerkat comes with free baby-sitting and nursemaid service from the subordinate females (who also will lactate to feed her pups). The downside is that all the other females want your job; as they get older, the young females start hip-checking, stealing food, and even picking fights. Often, the alpha kicks young competitors out of the group before they get old enough to pose a threat.
Positives: Your clan, your rules; mate selection; ritual grooming; cooperative breeding. Negatives: High risk.
Cooperative and matriarchical.
Killer whales (orcas): Killer whales have some of the most complex social structures known in nature and are found in large resident groups (mostly fish eaters), smaller transient groups (seal hunters), or offshore groups (of which relatively little is known). Killer whale societies are entirely structured around the maternal line, in a hierarchy of groups. The smallest of these is the matriline, which contains the oldest female and her direct descendents—as many as four generations in one (great grand-whale, grand-whales, mama whales, and baby whales). Several matrilines together make a pod, and groups of pods with the same dialect and shared maternal lineage form a clan. For killer whales in resident groups, the young live with their mothers for the their entire lives, while in the smaller, transient groups, females tend to depart once they become mothers of their own. Meanwhile, male killer whales are mama’s boys, maintaining a strong relationship with their mothers for life. Even siblings remain close after their mother dies. Unlike bees or meerkats, all females can mate as they wish, although almost always only with males from other pods. These close-knit groups are important for successful hunting, as well as for rearing young that require a lot of parental investment (like humans do!). A killer whale’s female relatives assist her during labor, and even help guide her 400 lb calf to the surface to take its first breath. This cooperative behavior is a key part of teaching calves important life skills like the complex group hunting strategies similar to those that wolf packs use.
Positives: Strong family structure, cooperative breeding, matrilineal. Negatives: The kids never leave home.
Don’t let the tusks fool you: It’s a she, and she’s the boss.
Elephants: Female elephants live together in small family groups, typically consisting of a matriarch and her young or closest relatives. The oldest female elephant in each family group gets the job, and the position is passed down to her oldest daughter when she dies. Matriarchs have a lot of social power but are also the source of important lore in the herd, like where the water is, how to avoid predators, and even how to use various tools like makeshift fly-swatters. Meanwhile, males live bachelor lifestyles, fending for themselves alone or in small groups after getting kicked out at puberty. Male and female elephants occasionally come together to socialize or mate, but otherwise live separately. Unlike bees, meerkats, and killer whales, female elephants have a lot less control in the mating process. Fertile females are followed around by aggressive bulls who rumble, produce a musky scent that they disperse by flapping their ears, and fight off other interested parties. For young female elephants, this mating behavior can be a bit intimidating, and so her female relatives will often stay by her side to provide moral support. After a two-year pregnancy, a female will give birth to a calf, which quickly becomes the center of herd life, as female relatives caress and welcome the newborn. The perks of elephant motherhood include free babysitting and protection from predators; females will circle the young when they sense danger. In some Asian elephant populations, multiple families have even been observed coming together to form specialized groups for nursing or juvenile care, like a cooperative preschool.
Positives: Strong family ties, cooperative parenting. Negatives: Lack of mate control, two-year pregnancy (!).
Many different kinds of matriarchy exist in the animal kingdom, as do many kinds of moms. Whether you’re a queen or a worker, an alpha or a beta, a subdominant or a matriarch, Happy Mother’s Day to moms everywhere.
The Living Elephants: Evolutionary Ecology, Behavior, and Conservation, Raman Sukumar. Oxford University Press, Oxford, UK. Kalahari Meerkat Project, Cambridge University
Killer Whales: The Natural History and Genealogy of Orcinus Orca in British Columbia and Washington, Kenneth C. Ford, Graeme M. Ellis, & Kenneth C. Balcomb. University of British Comumbia Press, Vancouver.
WebBeePop, Carl Hayden Bee Research Center, USDA Agricultural Research Service
[Photo credits: all photos are from Wikipedia with Creative Commons with Attribution liceneses except for #3, which is Public Domain: (1) A queen bee surrounded by her worker daughters. Photo by Waugsberg. (2) A meerkat in the Kalahari. Photo by Muriel Gottrop. (3) A mother-calf killer whale pair. Photo by Robert Pitman. (4) A matriarchal elephant and her family. Photo by Amoghavarsha.]Continue reading →
Liz Neeley: Science communicator extraordinaire and lover of fine fashion… and bread.
Liz Neeley is the assistant director at COMPASS where she helps develop and lead the communications trainings for scientists, and specializes in the social media and multimedia components of their workshops and outreach efforts. Before joining COMPASS, Liz studied the evolution and visual systems of tropical reef fishes at Boston University. After grad school, she helped communities and researchers in Fiji and Papua New Guinea connect their knowledge of local coral reefs ecosystems to the media. She also dabbled in international science policy while working on trade in deep-sea corals. Liz is currently based in Seattle, at the University of Washington. You can find Liz on Twitter (@LizNeeley) and on Google+. Also check our her passion projects, ScienceOnline Seattle and her SciLingual hangout series.
DXS: First, can you give us a quick overview of what your scientific background is and your current connection to science?
I was one of those kids who knew from a really young age what they wanted to be, and that was a fish biologist. Sea turtles, dolphins – no way – I wanted to study fish. My mom actually found an old picture I drew when I was in third grade about what I wanted to be when I grew up: it was me in a lab coat, holding a clipboard, and tanks of aquaria behind me.
You combine this with the fact that I am also a really stubborn person, and I just wanted to do science straight through all my schooling. Not just the coursework either – I did an NSF young scholars program in high school, was the captain of the engineering team, and, of course, was a mathlete.
I did my undergraduate work in marine biology at the University of Maryland. I did three years of research there on oyster reef restoration, and then went straight into my PhD at Boston University, where I studied the evolution of color patterns and visual systems in wrasses and parrotfish.
I actually did not finish my PhD. Life sort of knocked me sideways, and instead of finishing my PhD, I ended up taking a masters, and then going into the non-profit world. At first, I mostly worked on coral conservation in Fiji and Papua New Guinea, and I did a big project on deep sea corals.
After I left grad school, I started a 20-hour per week internship at an NGO called SeaWeb. Vikki Spruill, who was the founder and president, has killer instincts and a passion for women’s high fashion that I share. She had noticed coral jewelry coming down the runway in Milan, Paris, and NY. People just didn’t have any idea that these pieces of jewelry were actually animals, much less that they were deep sea corals.
So we launched a campaign called “Too Precious to Wear,” which partnered with high-end fashion and luxury designer to create alternatives to these deep sea corals – celebrating coral but not actually using it. The Tiffany & Co. Foundation was our major partner, and we got to throw a breakfast at Tiffany’s that brought in fashion editors from Mademoiselle and Vogue.
Everyone always dismisses women’s fashions as shallow and meaningless, but this ended up being this huge lever that got a lot of attention for deep sea coral conservation, and my piece was the science that pinned it all together. I got a taste of the international policy component of that as well, and headed to the Netherlands for CITES (the Convention on International Trade in Endangered Species) as part of the work. I knew the science, but certainly helped that I knew how to pronounce the names of the designers too – opportunities like that to bridge cultures that seem foreign to each other are tremendously powerful.
I currently work at COMPASS, which is an organization that works at the intersection of science, policy, and communication/media. Our tagline is “helping scientists find their voices and bringing science into the conversation.” For my part, this means, I teach science communications trainings around the country, helping researchers understand how social media works, how reporters find their stories, and how to overcome some of the obstacles that scientists often put in their own way when they talk about their work.
What I love about this work so much is that it keeps me in the science community – around people who are pursuing tough questions. That is how my brain works, it is how my soul works, and I want to be a part of it. The power of this for me is to be able to take in all of this knowledge that is generated by these scientists and help connect it to the broader world. I feel like this is the best contribution I can make.
DXS: What ways do you express yourself creatively that may not have a single thing to do with science?
I am a pretty artistic person – or at least I think of myself as a pretty artistic person! My creative outlets usually involve some kind of graphic design. I am always giving presentations for my work, and I constantly ask “what do my slides look like, and am I telling a good story?” I so lucky that I get to spend a lot of time thinking about imagery, visual storytelling, and how people react to art or data visualization.
I also paint and draw (though I wouldn’t really share those) and I cook. I am actually doing a bread baking experiment this year where I am trying out a different type of bread recipe every weekend.
It can be really funny because sometimes, if it has been a really stressful week, I will look for a recipe that really needs to be punched down or kneaded for a long time. It’s a good workout too! And then we have this amazing bread every weekend. It is all about the aesthetics for me – I host dinner parties, bake, have a great garden – all of that is sort of my own creative outlet.
Some experimental results from Liz’s bread project.
DXS: What is your favorite bread?
The delicious baguette
LN: Oh, the baguette. I made my own for the first time last weekend and it was really fantastic! I realize that baking is one of these things that, if you want to do it properly, you have to be very precise. You should weigh the ingredients. But I’m precise in the rest of my life. When it is the weekend and I am having fun, I kind of love it when the flour is just flying everywhere. As a result, my loaves are a little bit mutated, or just not quite right, but they are delicious! Some of my other favorites also includes a great focaccia (the recipe for it is below!).
DXS: Do you find that your scientific background informs your creativity, even though what you do may not specifically be scientific?
Yes, absolutely. It’s funny because when you asked the question about my creative outlets that have nothing to do with science, it was not entirely easy to answer. You know, science is who I am – it permeates everything I do. When I am baking the bread, I am thinking about the yeast and fermentation. When I am painting, I am thinking about color theory and visual perception – after all that would have been what my PhD was in!
Speaking of color theory, Joanne Manaster recently shared a “how good is your color vision?” quiz. I took that test immediately to see how I would do. That lead me on this interesting exploration around the literature, and I read one theory that Van Gogh might have had a certain type of color blindness. I love this question of how our brains interact with the world. In animal behavior the concept is called “umwelt” – each species has a unique sensory experience of the environment. I like to think about how that applies to individual people to a smaller degree.
I think about this all the time – science, creativity, art, aesthetics – it is all one beautiful and amazing thing to me.
DXS: Have you encountered situations in which your expression of yourself outside the bounds of science has led to people viewing you differently–either more positively or more negatively?
I accept the fact that, especially when it comes to strangers, we make up stories based on what we see – clothes, hair, etc. I know that this happens to me as well. When we talk about femininity, it’s no secret that I am a girly girl. I wear makeup and heels. That’s how I feel most like myself, how I feel best. I know that this doesn’t sit well with everybody, but that’s ok. I like to think that I hold my own. Give me enough time to speak my piece and I can back it up. I’ve got an interesting career, I am a geek, and it is not hard for me to connect with people once we start talking.
In science we say that we don’t have a dress code, but the reality is that we do. Maybe it’s unspoken, and sure it is not the same as you see in the business world, but when you look different from how everyone else looks, people do want comment on it. I don’t feel like it is particularly negative in my case, and I feel that it doesn’t impede me. What is most exciting is that it often opens up conversation – mostly with other women who say “oh I really like your dress, I’ve been wearing more dresses lately!”
When I was an undergrad, I was kind of oblivious to the whole dress code thing. One day, when I was in the lab, I was wearing this pink, strappy sundress, tied up the back, and these stupid platform sandals that were really tall (clearly not appropriate lab gear). I was scrubbing out this 100-gallon oyster tank and my advisor happened to walk by and he sees me doing this. I remember freezing – all of the sudden I was afraid he was going to mock me or lecture me, but he just said, “Oh, Liz… Keep on.”
My graduate advisor was the same way – he acknowledged who I am and didn’t bother about how I dress. We didn’t avoid the topic. It just wasn’t an issue. I hope that other women can have that same experience. It doesn’t matter if you are a tomboy or a girly-girl. I don’t care – I am not judging you. You don’t have to look like me because I am in a dress.
This is why I love this #IAmSciencememe, and the whole “be yourself” mentality. And that is what I am going to do. I’ve decided to be myself. I accept the fact that not everyone will like the look of me. But, I think that we will eventually get to the point where we understand that science can be presented in lots of different ways.
DXS: Have you found that your non-science expression of creativity/activity/etc. has in any way informed your understanding of science or how you may talk about it or present it to others?
For me, my job with COMPASS really is sitting at this nexus of asking how we share science with people who aren’t intrinsically fascinated by it or connected to it. This is very much a ripe field for thinking about creative expression. Mostly, we come at it in terms of verbal presentations, storytelling and written materials, but then I specialize in the social media and multimedia components. I am always thinking about everything I am reading and seeing – news, art, music, fiction – and how we can apply what resonates with others in these non-science realms. It is very much a two-way thing; my science informs my creativity and my creativity informs my science. That makes it really fulfilling and exciting for me.
I see this in terms of the ability to make connections. When I am standing up in front of a group of researchers doing a social media training, I am making pop-culture references, alluding to literary works, quoting song lyrics. When you get it right, you can see someone’s eyes light up. It’s just another way to connect – people sit up and pay attention if you can make a meaningful reference to the artist they love or the book they just read.
One of the questions we always use in our trainings is “so what?” So you are telling me about your science, but why should I care? Miles Davis has a famous song “So What?” and we play that in the background. It makes people smile. It makes it memorable. I love that. I really like this idea that we should be using the fullness of who we are and our creative selves, including all of the sensory modalities, to talk about the very abstract and difficult scientific topics we care about so much.
(DXS editor’s side note: A portion of the previous paragraph was delivered to me in song. What’s not to smile about?!?!)
DXS: How comfortable are you expressing your femininity and in what ways? How does this expression influence people’s perception of you in, say, a scientifically oriented context?
I feel very comfortable in my own skin, and who I am and where I come from does tend to be a classically feminine look (at least in terms of clothing choices and how I wear my hair). I am never quite certain the exact definition of “femininity”, but I don’t think how I look so much influences people’s perception of me as much as it opens up opportunities for us to discuss gender and personality and science.
Part of what I do for my work is to help scientists understand that in journalism, we need characters. So, I have the obligation to walk my talk – we are all the main characters in our own lives and we have to live with that and be true to that.
It brings up interesting questions of personality and privacy. I feel pretty comfortable talking about my clothes and my art and my dogs and my bread baking – but I also know that a lot of people don’t want that type of stuff out there. I like the challenge of helping them tell their own science stories and shine through as interesting people in a way that is authentic and represents who they are in a way that works for them.
DXS: Do you think that the combination of your non-science creativity and scientific-related activity shifts people’s perspectives or ideas about what a scientist or science communicator is? If you’re aware of such an influence, in what way, if any, do you use it to (for example) reach a different corner of your audience or present science in a different sort of way?
Sure, I think that I sometimes surprise people. For example, in the world of communications and journalism, we are seeing more and more that coding and programming has great value. To just look at me, you might not believe that I geek out over altmetrics and that I miss using MatLab.
It suprises people when they find this out, and I sort of like that. I know what it feels like to walk into a room and to be dismissed. I relish these opportunities because I consider them a challenge. Instead of feeling offended (though it can get tiring), my approach is thinking, “Guess what! I have something interesting to say, and you and I are actually going to connect, even though you don’t see it yet.”
I think that this sort of willingness to interact is something I try to help the scientists that I work with to understand. Maybe you think that you are going to be met with great opposition toward some subject like climate change, but if you have the willingness to approach it without assuming the worst, it opens new opportunties. I’m no Pollyanna, but I think relentless optimism and a commitment to finding common ground with others is very effective.
When I introduce social media to scientists, it has changed a lot over the last three years, but there is still a lot of skepticism and some outright scorn for “all those people online.” I like to encourage taking a step back from that in order to reveal all of the awesome things going on online and the ways you might engage. I truly enjoy the process of turning skeptics into something other than skeptics – I might not change them into believers, but they will at least be surprised and interested onlookers.
Liz Neeley’s Favorite Focaccia
Scant 4 cups white bread flour
1 tablespoon salt
Scant 1/2 cup olive oil
1 packet of active dry yeast
1 1/4 cups warm water
Favorite olives, roughly chopped if you prefer
Handful of fresh basil
Start this mid-afternoon (between 3 and 4 hours before you want to eat it, depending on how fast you are in the kitchen)
1.In a large bowl, combine the flour and salt with 1Ž4 cup of the olive oil, the yeast & the water. Mix with your hands for about 3 minutes.
2.Lightly dust your countertop with flour and knead your dough for 6 minutes. Enjoy your arm workout and stress relief exercise!
3.The dough will be pretty sticky. Put it back in the bowl, cover it with a damp cloth, and let stand at room temperature for 2 hours.
4.Mix 1Ž2 or more of your olives and all the basil into the dough, and try to get them evenly distributed. It won’t be perfect, but it will be delicious.
5.Dump the dough onto a lined baking sheet. Flatten it with your hands until it’s a big rectangle about 1″/2.5cm thick. Slather with olive oil. Let rise for 1 hour.
6.Preheat your oven to 425°F/220°C
7.Sprinkle with flaky sea salt and drizzle with more olive oil if you want. Bake for 25 minutes or until golden.
8.Make your neighbors jealous with the amazing smell of baked bread wafting from your house.
Are some of these possible signs of breast cancer present in a famous work of art? Image: public domain, US gov
by Liza Gross, contributor
[Ed. note: This article was originally posted on KQED QUEST on October 3, 2012. It is reposted here with kind permission.]
Just a generation ago, October belonged to the colors of fall, when “every green thing loves to die in bright colors,” as Henry Ward Beecher said. (Growing up back East, you read a lot of odes to fall foliage in school.) For years after moving to the Bay Area from Pennsylvania, I felt a twinge of melancholy when October rolled around, knowing the once-demure woodlands would let loose in a fleeting blaze of brash reds and orange-tinged yellows without me.
Now, of course, October belongs to all things pink, as high-profile outfits from the NFL to Ace Hardware set aside 31 days to raise awareness and money for Breast Cancer Awareness Month. (National Breast Cancer Awareness Month was launched in 1985 by CancerCare, a nonprofit cancer support group, and cancer-drug maker AstraZeneca.)
But as women’s health advocate Dr. Susan Love says, awareness of the disease isn’t the issue. “When the NFL is wearing pink gloves, I think you can say we’re aware,” she said last year. “But the awareness isn’t enough.”
It’s a message that gets lost in an ocean of pink-ribbon products (from bagels and teddy bears to vodka and wine glasses), even though critics like the San Francisco-based nonprofit Breast Cancer Action have warned about “pinkwashing” for years, urging people to look behind the feel-good messages to see who’s really benefiting from the commercialization of cancer.
Breast Cancer Action’s Think Before You Pink—Raise a Stink! campaign encourages consumers to think critically about pink products and ask four simple questions to find out what proportion of proceeds go to breast cancer programs and whether the products sold are safe. The group has especially targeted cosmetics companies for marketing pink merchandise even as they sell products with toxic ingredients. (For more information, download the group’s 30-page “toolkit”.)
The group also urges companies to be more transparent and has long called out those it believes use a good cause to increase their bottom line.
Like Eureka, which donated a dollar for every vacuum cleaner sold in its “Clean for the Cure” campaign. Or American Express, which donated a penny per transaction in its “Charge for the Cure.” Both companies bowed out of the pink sweepstakes after Breast Cancer Action asked just how breast cancer patients were benefiting from the campaigns in a 2002 ad in the New York Times.
In October 2000, the San Francisco-based advocacy group
Breast Cancer Action ran a full page ad in the New York Times
West Coast Edition with text (not shown) inviting readers to
participate in its ”Stop Cancer Where It Starts” Campaign.
The campaign criticized breast cancer awareness campaigns
for pushing early detection and mammograms
(without acknowledging their limitations) while ignoring prevention.
(Image: Courtesy Breast Cancer Action)
Others, like KFC with its 2010 “Buckets for the Cure” campaign, climb on the pink bandwagon to peddle decidedly unhealthy products. Stephen Colbert’s take on the “pink bucket dilemma” shows just how ludicrous cause marketing has become. (Forward to 1:13.)
But even when money goes to breast cancer programs and not corporate coffers, is it going to the right place? Love (and several advocacy groups) has said for years that we need to shift our focus from cures to causes—and prevention.
If we can develop a vaccine for cervical cancer, says Love, why not for breast cancer? Early results of a clinical trial show promising results for a vaccine designed to prevent recurrence of one form of breast cancer. (The data were presented at a meeting and have not yet gone through peer review.)
As I wrote in May, Love’s Research Foundation is looking for volunteers in her online Army of Women to identify potential causes in order to eradicate the disease. (Anyone can sign up.)
In the late 1990s, The Breast Cancer Fund, the American Cancer Society,
and the Susan G. Komen Breast Cancer Foundation invited American
artists and writers to submit work about their breast cancer experiences.
The resulting exhibit (and book)—Art.Rage.Us.—opened in 1998
at San Francisco’s Main Library. At the time, project coordinator and
Breast Cancer Action Co-founder Susan Claymon said,
“Art.Rage.Us. presents deeply moving and beautiful expressions
from women with breast cancer, along with intensely personal
statements that provide a window into their hearts and minds.”
Claymon died of breast cancer in 2000. She was 61.
Prevention is also a primary concern for the Athena Breast Health Network, a partnership of the five University of California medical centers that collects personalized data on breast cancer patients to optimize treatment and ultimately figure out how to stop cancer before it starts. The site also includes a comprehensive list of breast cancer risk factors.
Recent research suggests that the biology behind one of the listed risk factors, dense breast tissue, may be more complicated than previously thought. Earlier studies found that women with dense breasts had a higher risk of developing breast cancer. (And this finding led to the“right to know” legislation that Gov. Brown recently signed, requiring doctors to tell women if their mammograms show they have dense breasts.) But a recent study in the Journal of the National Cancer Institute suggests that women with denser breasts are not more likely to die of breast cancer. The greatest risk was found for women who had the fattiest breast tissue, a condition linked to obesity. This suggests that if you have dense breast tissue, you may be more likely to get cancer—but not die of it. Love’s blog explained the significance of the findings:
The recent study on breast density showed us, yet again, that women who are obese when they are diagnosed with breast cancer are more likely to die of breast cancer than women who are not obese. Doctors need to do more than tell women about their breast density or remind them to get a mammogram. They need to be teaching women the importance of exercising, losing weight (if necessary) and eating a well-balanced diet—both before and after a breast cancer diagnosis.Continue reading →
First of all, in the context of science, you should never speak of evolution as a “theory.” There is no theory about whether or not evolution happens. It is a fact.
Scientists have, however, developed tested theories about how evolution happens. Although several proposed and tested processes or mechanisms exist, the most prominent and most studied, talked about, and debated, is Charles Darwin’s idea that the choices of nature guide these changes. The fame and importance of his idea, natural selection, has eclipsed the very real existence of other ways that populations can change over time.
Evolution in the biological sense does not occur in individuals, and the kind of evolution we’re talking about here isn’t about life’s origins. Evolution must happen at least at the populationlevel. In other words, it takes place in a group of existing organisms, members of the same species, often in a defined geographical area.
We never speak of individuals evolving in the biological sense. The population, a group of individuals of the same species, is the smallest unit of life that evolves.
To get to the bottom of what happens when a population changes over time, we must examine what’s happening to the gene combinations of the individuals in that population. The most precise way to talk about evolution in the biological sense is to define it as “a change in the allele frequency of a population over time.” A gene, which contains the code for a protein, can occur in different forms, or alleles. These different versions can mean that the trait associated with that protein can differ among individuals. Thanks to mutations, a gene for a trait can exist in a population in these different forms. It’s like having slightly different recipes for making the same cake, each producing a different version of the cake, except in this case, the “cake” is a protein.
Natural selection: One way evolution happens
Charles Darwin, a smart, thoughtful, observant man. Via Wikimedia.
Charles Darwin, who didn’t know anything about alleles or even genes (so now you know more than he did on that score), understood from his work and observations that nature makes certain choices, and that often, what nature chooses in specific individuals turns up again in the individuals’ offspring. He realized that these characteristics that nature was choosing must pass to some offspring. This notion of heredity–that a feature encoded in the genes can be transmitted to your children–is inherent now in the theory of natural selection and a natural one for most people to accept. In science, an observable or measurable feature or characteristic is called a phenotype, and the genes that are the code for it are called its genotype. The color of my eyes (brown) is a phenotype, and the alleles of the eye color genes I have are the genotype.
What is nature selecting any individual in a population to do? In the theory of natural selection, nature chooses individuals that fit best into the current environment to pass along their “good-fit” genes, either through reproduction or indirectly through supporting the reproducer. Nature chooses organisms to survive and pass along those good-fit genes, so they have greater fitness.
Fitness is an evolutionary concept related to an organism’s reproductive success, either directly (as a parent) or indirectly (say, as an aunt or cousin). It is measured technically based on the proportion of an individual’s alleles that are represented in the next generation. When we talk about “fitness” and “the fittest,” remember that fittest does not mean strong. It relates more to a literal fit, like a square peg in a square hole, or a red dot against a red background. It doesn’t matter if the peg or dot is strong, just whether or not it fits its environment.
One final consideration before we move onto a synthesis of these ideas about differences, heredity, and reproduction: What would happen if the population were uniformly the same genetically for a trait? Well, when the environment changed, nature would have no choice to make. Without a choice, natural selection cannot happen–there is nothing to select. And the choice has to exist already; it does not typically happen in response to a need that the environment dictates. Usually, the ultimate origin for genetic variation–which underlies this choice–is mutation, or a change in a DNA coding sequence, the instructions for building a protein.
Don’t make the mistake of saying that an organism adapts by mutating in response to the environment. The mutations (the variation) must already be present for nature to make a choice based on the existing environment.
The Modern Synthesis
Darwin presented his ideas about nature’s choices in an environmental context, he did so in a book with a very long title that begins, On the Origin of Species by Means of Natural Selection.Darwinknew his audience and laid out his argument clearly and well, with one stumbling block: How did all that heredity stuff actually work?
We now know–thanks to a meticulous scientist named Gregor Mendel (who also was a monk), our understanding of reproductive cell division, and modern genetics–exactly how it all works. Our traits–whether winners or losers in the fitness Olympics–have genes that determine them. These genes exist in us in pairs, and these pairs separate during division of our reproductive cells so that our offspring receive one member or the other of the pair. When this gene meets its coding partner from the other parent’s cell at fertilization, a new gene pair arises. This pairing may produce a similar outcome to one of the parents or be a novel combination that yields some new version of a trait. But this separating and pairing is how nature keeps things mixed up, setting up choices for selection.
With a growing understanding in the twentieth century of genetics and its role in evolution by means of natural selection, a great evolutionary biologist named Ernst Mayr (1904–2005) guided a meshing of genetics and evolution (along with other brilliant scientists including Theodosius Dobzhansky, George Simpson, and R.A. Fisher) into what is called The Modern Synthesis. This work encapsulates (dare I say, “synthesizes?”) concisely and beautifully the tenets of natural selection in the context of basic genetic inheritance. As part of his work, Mayr distilled Darwin’s ideas into a series of facts and inferences.
Facts and Inferences
Mayr’s distillation consists of five facts and three inferences, or conclusions, to draw from those facts.
The first fact is that populations have the potential to increase exponentially. A quick look at any graph of human population growth illustrates that we, as a species, appear to be recognizing that potential. For a less successful example, consider the sea turtle. You may have seen the videos of the little turtle hatchlings valiantly flippering their way across the sand to the sea, cheered on by the conservation-minded humans who tended their nests. What the cameras usually don’t show is that the vast majority of these turtle offspring will not live to reproduce. The potential for exponential growth is there, based on number of offspring produced, but…it doesn’t happen.
The second fact is that not all offspring reproduce, and many populations are stable in size. See “sea turtles,” above.
The third fact is that resources are limited. And that leads us to our first conclusion, or inference: there is a struggle among organisms for nutrition, water, habitat, mates, parental attention…the various necessities of survival, depending on the species. The large number of offspring, most of which ultimately don’t survive to reproduce, must compete, or struggle, for the limited resources.
Fact four is that individuals differ from one another. Look around. Even bacteria of the same strain have their differences, with some more able than others to with stand an antibiotic onslaught. Look at a crowd of people. They’re all different in hundreds of ways.
Fact five is that much about us that is different lies in our genes–it is inheritable. Heredity undeniably exists and underlies a lot of our variation.
So we have five facts. Now for the three inferences:
First, there is that struggle for survival, thanks to so many offspring and limited resources. See “sea turtle,” again.
Second, different traits will be passed on differentially. Put another way: Winner traits are more likely to be passed on.
And that takes us to our final conclusion: if enough of these “winner” traits are passed to enough individuals in a population, they will accumulate in that population and change its makeup. In other words, the population will change over time. It will be adapted to its environment. It will evolve.
Darwin presented his idea of natural selection, he knew he had an audience to win over. He pointed out that people select features of organisms all the time and breed them to have those features. Darwin himself was fond of breeding pigeons with a great deal of pigeony variety. He noted that unless the pigeons already possessed traits for us to choose, we not would have that choice to make. But we do have choices. We make super-woolly sheep, dachshunds, and heirloom tomatoes simply by selecting from the variation nature provides and breeding those organisms to make more with those traits. We change the population over time.
Darwin called this process of human-directed evolution artificial selection. It made great sense for Darwinbecause it helped his reader get on board. If people could make these kinds of choices and wreak these kinds of changes, why not nature? In the process,
Darwin also described this second way evolution can happen: human-directed evolution. We’re awash in it today, from our accidental development of antibiotic-resistant bacteria to wheat that resists devastating rust.
Genetic drift: fixed or lost
What about traits that have no effect either way, that are just there? One possible example in us might be attached earlobes. Good? Bad? Ugly? Well…they don’t appear to have much to do with whether or not we reproduce. They’re just there.
When a trait leaves nature so apparently disinterested, the alleles underlying it don’t experience selection. Instead, they drift in one direction or another, to extinction or 100 percent frequency. When an allele drifts to disappearance, we say that it is lost from the population. When it drifts to 100 percent presence, we say that it has become fixed. This process of evolution by genetic drift reduces variation in a population. Eventually, everyone will have it, or no one will.
Gene flow: genes in, genes out
Another way for a population to change over time is for it to experience a new infusion of genes or to lose a lot of them. This process of gene flow into or out of the population occurs because of migration in or out. Either of these events can change the allele frequency in a population, and that means that gene flow is another was that evolution can happen.
If gene flow happens between two different species, as can occur more with plants, then not only has the population changed significantly, but the new hybrid that results could be a whole new species. How do you think we get those tangelos?
Horizontal gene transfer
One interesting mechanism of evolution is horizontal gene transfer. When we think of passing along genes, we usually envision a vertical transfer through generations, from parent to offspring. But what if you could just walk up to a person and hand over some of your genes to them, genes that they incorporate into their own genome in each of their cells?
Of course, we don’t really do that–at least, not much, not yet–but microbes do this kind of thing all the time. Viruses that hijack a cell’s genome to reproduce can accidentally leave behind a bit of gene and voila! It’s a gene change. Bacteria can reach out to other living bacteria and transfer genetic material to them, possibly altering the traits of the population.
Sometimes, events happen at a large scale that have huge and rapid effects on the overall makeup of a population. These big changes mark some of the turning points in the evolutionary history of many species.
The word bottleneck pretty much says it all. Something happens over time to reduce the population so much that only a relatively few individuals survive. A bottleneck of this sort reduces the variability of a population. These events can be natural–such as those resulting from natural disasters–or they can be human induced, such as species bottlenecks we’ve induced through overhunting or habitat reduction.
Founder effect: starting small
Sometimes, the genes flow out of a population. This flow occurs when individuals leave and migrate elsewhere. They take their genes with them (obviously), and the populations they found will initially carry only those genes. Whatever they had with them genetically when they founded the population can affect that population. If there’s a gene that gives everyone a deadly reaction to barbiturates, that population will have a higher-than-usual frequency of people with that response, thanks to this founder effect.
Gene flow leads to two key points to make about evolution: First, a population carries only the genes it inherits and generally acquires new versions through mutation or gene flow. Second, that gene for lethal susceptibility to a drug would be meaningless in a natural selection context as long as the environment didn’t include exposure to that drug. The take-home message is this: What’s OK for one environment may or may not be fit for another environment. The nature of Nature is change, and Nature offers no guarantees.
Hardy-Weinberg: when evolution is absent
With all of these possible mechanisms for evolution under their belts, scientists needed a way to measure whether or not the frequency of specific alleles was changing over time in a given population or staying in equilibrium. Not an easy job. They found–“they” being G. H. Hardy and Wilhelm Weinberg–that the best way to measure this was to predict what the outcome would be if there were no change in allele frequencies. In other words, to predict that from generation to generation, allele frequencies would simply stay in equilibrium. If measurements over time yielded changing frequencies, then the implication would be that evolution has happened.
Defining “Not Evolving”
So what does it mean to not evolve? There are some basic scenarios that must exist for a population not to be experiencing a change in allele frequency, i.e., no evolution. If there is a change, then one of the items in the list below must be false:
·Very large population (genetic drift can be a strong evolutionary mechanism in small populations)
·No migrations (in other words, no gene flow)
·No net mutations (no new variation introduced)
·Random mating (directed mating is one way nature selects organisms)
·No natural selection
In other words, a population that is not evolving is experiencing a complete absence of evolutionary processes. If any one of these is absent from a given population, then evolution is occurring and allele frequencies from generation to generation won’t be in equilibrium.
Arguably the most famous of the egg-laying monotremes, the improbable- seeming platypus. License.
One of the best examples of the influences of environmental pressures is what happens in similar environments a world apart. Before the modern-day groupings of mammals arose, the continent of
Australiaseparated from the rest of the world’s land masses, taking the proto-mammals that lived there with it. Over the ensuing millennia, these proto-mammals in Australiaevolved into the native species we see today on that continent, all marsupialsor monotremes.
Among mammals, there’s a division among those that lay eggs (monotremes), those that do most gestating in a pouch rather than a uterus (marsupials), and eutherians, which use a uterus for gestation (placental mammals).
Elsewhere in the world, most mammals developed from a common eutherian ancestor and, where marsupials still persisted, probably outcompeted them. In spite of this lengthy separation and different ancestry, however, for many of the examples of placental mammals, Australiahas a similar marsupial match. There’s the marsupial rodent that is like the rat. The marsupial wolf that is like the placental wolf. There’s even a marsupial anteater to match the placental one.
How did that happen an ocean apart with no gene flow? The answer is natural selection. The environment that made an organism with anteater characteristics best fit in South America was similar to the environment that made those characteristics a good fit in
Australia. Ditto the rats, ditto the wolf.
When similar environments result in unrelated organisms having similar characteristics, we call that process convergent evolution. It’s natural selection in relatively unrelated species in parallel. In both regions, nature uses the same set of environmental features to mold organisms into the best fit.
Note: This explanation of evolution and how it happens is not intended to be comprehensive or detailed or to include all possible mechanisms of evolution. It is simply an overview. In addition, it does not address epigenetics, which will be the subject of a different explainer.