Biology Explainer: The big 4 building blocks of life–carbohydrates, fats, proteins, and nucleic acids

The short version
  • 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.
Carbohydrates

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.

Proteins

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.

Nucleic Acids

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.


 By Emily Willingham, DXS managing editor 
This material originally appeared in similar form in Emily Willingham’s Complete Idiot’s Guide to College Biology

Science, health, medical news freaking you out? Do the Double X Double-Take first

Handy short-form version.

Have you seen the headlines? Skip them
You’ve probably seen a lot of headlines lately about autism and various behaviors, ways of being, or “toxins” that, the headlines tell you, are “linked” to it. Maybe you’re considering having a child and are mentally tallying up the various risk factors you have as a parent. Perhaps you have a child with autism and are now looking back, loaded with guilt that you ate high-fructose corn syrup or were overweight or too old or too near a freeway or not something enough that led to your child’s autism. Maybe you’re an autistic adult who’s getting a little tired of reading in these stories about how you don’t exist or how using these “risk factors” might help the world reduce the number of people who are like you.

Here’s the bottom line: No one knows precisely what causes the extremely diverse developmental difference we call autism. Research from around the world suggests a strong genetic component [PDF]. What headlines in the United States call an “epidemic” is, in all likelihood, largely attributable to expanded diagnostic inclusion, better identification, and, ironically, greater awareness of autism. In countries that have been able to assess overall population prevalence, such as the UK, rates seem to have held steady at about 1% for decades, which is about the current levels now identified among 8-year-olds in the United States. 

What anyone needs when it comes to headlines honking about a “link” to a specific condition is a mental checklist of what the article–and whatever research underlies it–is really saying. Previously, we brought you Real vs Fake Science: How to tell them apart. Now we bring you our Double X Double-Take checklist. Use it when you read any story about scientific research and human health, medicine, biology, or genetics.

The Double X Double-Take: What to do when reading science in the news
1. Skip the headline. Headlines are often misleading, at best, and can be wildly inaccurate. Forget about the headline. Pretend you never even saw the headline.

2. What is the basis of the article? Science news originates from several places. Often it’s a scientific paper. These papers come in several varieties. The ones that report a real study–lots of people or mice or flies, lots of data, lots of analysis, a hypothesis tested, statistics done–is considered “original research.” Those papers are the only ones that are genuinely original scientific studies. Words to watch for–terms that suggest no original research at all–are “review,” “editorial,” “perspective,” “commentary,” “case study” (these typically involve one or only a handful of cases, so no statistical analysis), and “meta-analysis.” None of these represents original findings from a scientific study. All but the last two are opinion. Also watch for “scientific meeting” and “conference.” That means that this information was presented without peer review at a scientific meeting. It hasn’t been vetted in any way.

3. Look at the words in the article. If what you’re reading contains words like “link,” “association,” “correlation,” or “risk,” then what the article is describing is a mathematical association between one thing (e.g., autism) and another (e.g., eating ice cream). It is likely not describing a biological connection between the two. In fact, popular articles seem to very rarely even cover scientific research that homes in on the biological connections. Why? Because these findings usually come in little bits and pieces that over time–often quite a bit of time–build into a larger picture showing a biological pathway by which Variable 1 leads to Outcome A. That’s not generally a process that’s particularly newsworthy, and the pathways can be both too specific and extremely confusing.

4. Look at the original source of the information. Google is your friend. Is the original source a scientific journal? At the very least, especially for original research, the abstract will be freely available. A news story based on a journal paper should provide a link to that abstract, but many, many news outlets do not do this–a huge disservice to the interested, engaged reader. At any rate, the article probably includes the name of a paper author and the journal of publication, and a quick Google search on both terms along with the subject (e.g., autism) will often find you the paper. If all you find is a news release about the paper–at outlets like ScienceDaily or PhysOrg–you are reading marketing materials. Period. And if there is no mention of publication in a journal, be very, very cautious in your interpretation of what’s being reported.

5. Remember that every single person involved in what you’re reading has a dog in the hunt. The news outlet wants clicks. For that reason, the reporter needs clicks. The researchers probably want attention to their research. The institutions where the researchers do their research want attention, prestige, and money. A Website may be trying to scare you into buying what they’re selling. Some people are not above using “sexy” science topics to achieve all of the above. Caveat lector

6. Ask a scientist. Twitter abounds with scientists and sciencey types who may be able to evaluate an article for you. I receive daily requests via email, Facebook, and Twitter for exactly that assistance, and I’m glad to provide it. Seriously, ask a scientist. You’ll find it hard to get us to shut up. We do science because we really, really like it. It sure ain’t for the money. [Edited to add: But see also an important caveat and an important suggestion from Maggie Koerth-Baker over at Boing Boing and, as David Bradley has noted over at ScienceBase, always remember #5 on this list when applying #6.] 

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Case Study
Lately, everyone seems to be using “autism” as a way to draw eyeballs to their work. Below, I’m giving my own case study of exactly that phenomenon as an example of how to apply this checklist.

1. Headline: “Ten chemicals most likely to cause autism and learning disabilities” and “Could autism be caused by one of these 10 chemicals?” Double X Double-Take 1: Skip the headline. Check. Especially advisable as there is not one iota of information about “cause” involved here.

2. What is the basis of the articleEditorialConference. In other words, those 10 chemicals aren’t something researchers identified in careful studies as having a link to autism but instead are a list of suspects the editorial writers derived, a list that they’d developed two years ago at the mentioned conference. 

3. Look at the words in the articles. Suspected. Suggesting a link. In other words, what you’re reading below those headlines does not involve studies linking anything to autism. Instead, it’s based on an editorial listing 10 compounds [PDF] that the editorial authors suspect might have something to do with autism (NB: Both linked stories completely gloss over the fact that most experts attribute the rise in autism diagnoses to changing and expanded diagnostic criteria, a shift in diagnosis from other categories to autism, and greater recognition and awareness–i.e., not to genetic changes or environmental factors. The editorial does the same). The authors do not provide citations for studies that link each chemical cited to autism itself, and the editorial itself is not focused on autism, per se, but on “neurodevelopmental” derailments in general.

4. Look at the original source of information. The source of the articles is an editorial, as noted. But one of these articles also provides a link to an actual research paper. The paper doesn’t even address any of the “top 10″ chemicals listed but instead is about cigarette smoking. News stories about this study describe it as linking smoking during pregnancy and autism. Yet the study abstract states that they did not identify a link, saying “We found a null association between maternal smoking and pregnancy in ASDs and the possibility of an association with a higher-functioning ASD subgroup was suggested.” In other words: No link between smoking and autism. But the headlines and how the articles are written would lead you to believe otherwise. 

5. Remember that every single person involved has a dog in this hunt. Read with a critical eye. Ask yourself, what are people saying vs what real support exists for their assertions? Who stands to gain and in what way from having this information publicized? Think about the current culture–does the article or the research drag in “hot” topics (autism, obesity, fats, high-fructose corn syrup, “toxins,” Kim Kardashian) without any real basis for doing so? 

6. Ask a scientist. Why, yes, I am a scientist, so I’ll respond. My field of research for 10 years happens to have been endocrine-disrupting compounds. I’ve seen literally one drop of a compound dissolved in a trillion drops of solvent shift development of a turtle from male to female. I’ve seen the negative embryonic effects of pesticides and an over-the-counter antihistamine on penile development in mice. I know well the literature that runs to the thousands of pages indicating that we’ve got a lot of chemicals around us and in us that can have profound influences during sensitive periods of development, depending on timing, dose, species, and what other compounds may be involved. Endocrine disruptors or “toxins” are a complex group with complex interactions and effects and can’t be treated as a monolith any more than autism should be.

What I also know is that synthetic endocrine-disruptors have been around for more than a century and that natural ones for far, far longer. Do I think that the “top 10″ chemicals require closer investigation and regulation? Yes. But not because I think they’re causative in some autism “epidemic.” We’ve got sufficiently compelling evidence of their harm already without trying to use “autism” as a marketing tool to draw attention to them. Just as a couple of examples: If coal-burning pollution (i.e., mercury) were causative in autism, I’d expect some evidence of high rates in, say, Victorian London, where the average household burned 11 tons of coal a year. If modern lead exposures were causative, I’d be expecting records from notoriously lead-burdened ancient Rome containing descriptions of the autism epidemic that surely took it over. 

Bottom line: We’ve got plenty of reasons for concern about the developmental effects of the compounds on this list. But we’ve got very limited reasons to make autism a focal point for testing them. Using the Double X Double-Take checklist helps demonstrate that.

By Emily Willingham, DXS managing editor 

Motherhood, war, and attachment: what does it all mean?


The antebellum tales
Scene 1: Two fathers encounter each other at a Boy Scout meeting. After a little conversation, one reveals that his son won’t be playing football because of concerns about head injuries. The other father reveals that he and his son love football, that they spoke with their pediatrician about it, and that their son will continue with football at least into middle school. There’s a bit of wary nodding, and then, back to the Pinewood Derby.

Scene 2: Two mothers meet on a playground. After a little conversation about their toddlers, one mother mentions that she still breastfeeds and practices “attachment parenting,” which is why she has a sling sitting next to her. The other mother mentions that she practiced “cry it out” with her children but that they seem to be doing well and are good sleepers. Then one of the toddlers begins to cry, obviously hurt in some way, and both mothers rush over together to offer assistance.

Scene 3: In the evening, one of these parents might say to a partner, “Can you believe that they’re going to let him play football?” or “I can’t believe they’re still breastfeeding when she’s three!” Sure. They might “judge” or think that’s something that they, as parents, would never do.

But which ones are actually involved in a war?

War. What is it good for?

I can’t answer that question, but I can tell you the definition of ‘war’: “a state of armed conflict between different nations or states or different groups within a nation or state.” Based on this definition and persistent headlines about “Mommy Wars,” you might conclude that a visit to your local playground or a mom’s group outing might require decking yourself out cap-á-pie in Kevlar. But the reality on the ground is different. There is no war. Calling disputes and criticisms and judgments about how other people live “war” is like calling a rowboat on a pond the Titanic. One involves lots of energy release just to navigate relatively placid waters while the other involved a tremendous loss of life in a rough and frigid sea. Big difference.

I’m sure many mothers can attest to the following: You have friends who also are mothers. I bet that for most of us, those friends represent a spectrum of attitudes about parenting, education, religion, Fifty Shades of Grey, recycling, diet, discipline, Oprah, and more. They also probably don’t all dress just like you, talk just like you, have the same level of education as you, same employment, same ambitions, same hair, or same toothpaste. And I bet that for many of us, in our interactions with our friends, we have found ourselves judging everything from why she insists on wearing those shoes to why she lets little Timmy eat Pop Tarts. Yet, despite all of this mental observation and, yes, judging, we still manage to get along, go out to dinner together, meet at one another’s homes, and gab our heads off during play dates.

That’s not a war. That’s life. It’s using our brains as shaped by our cultural understanding and education and rejection or acceptance of things from our own upbringing and talks with medical practitioners and books we’ve read and television shows we’ve watched and, for some of us, Oprah. Not one single friend I have is a cookie cutter representation of me or how I parent. Yet, we are not at war. We are friends. Just because people go online and lay out in black and white the critiques that are in their heads doesn’t mean “war” is afoot. It means expressing the natural human instinct to criticize others in a way that we think argues for Our Way of Doing Things. Online fighting is keeping up with the virtual Joneses. In real life, we are friends with the Joneses, and everyone tacitly understands what’s off limits within the boundaries of that friendship. That’s not war. It’s friendly détente.

The reality doesn’t stop the news media from trying to foment wars, rebellions, and full-on revolutions with provocative online “debates” and, lately, magazine covers. The most recent, from Time, features a slender mother, hand on cocked hip, challenging you with her eyes as she nurses her almost-four-year-old son while he stands on a chair. As Time likely intended, the cover caused an uproar. We’ve lampooned it ourselves (see above).

But the question the cover asks in all caps, “Are you mom enough?” is even more manipulative than the cover because it strikes at the heart of all those unspoken criticisms we think–we know–other women have in their heads about our parenting. What we may not consider is that we, too, are doing the same, and still… we are not actually at war. We’re just women, judging ourselves and other women, just like we’ve done since the dawn of time. It’s called “using your brain.” Inflating our interactions and fairly easily achieved parental philosophy détentes to “war” caricatures us all as shrieking harpies, incapable of backing off and being reasonable.

The real question to ask isn’t “Are you mom enough?” In fact, it’s an empty question because there is no answer. Your parenting may be the most perfect replica of motherhood since the Madonna (the first one), yet you have no idea how that will manifest down the road in terms of who your child is or what your child does. Whether you’re a Grizzly or a Tiger or a Kangaroo or a Panda mother, there is no “enough.”

So, instead of asking you “Are you mom enough?”, in keeping with our goal of bringing women evidence-based science, we’ve looked at some of the research describing what might make a successful parent–child relationship. Yes, the answer is about attachment, but not necessarily of the physical kind. So drop your guilt. Read this when you have time. Meanwhile, do your best to connect with your child, understand your child, and respond appropriately to your child.  

Why? Because that is what attachment is–the basic biological response to a child’s needs. If you’re not a nomad or someone constantly on the move, research suggests that the whole “physically attached to me” thing isn’t really a necessary manifestation of attachment. If you harken to it and your child enjoys it (mine did not) and it works for you without seeming like, well, an albatross around your neck, go for it.

What is attachment?

While attachment as a biological norm among primates has been around as long as primates themselves, humans are more complicated than most primates. We have theories. Attachment theory arose from the observations of a couple of human behaviorists or psychologists (depending on whom you ask), John Bowlby and Mary Ainsworth. Bowlby derived the concept of attachment theory, in which an infant homes in on an attachment figure as a “safe place.” The attachment figure, usually a parent, is the person who responds and is sensitive to the infant’s needs and social overtures. That parent is typically the mother, and disruption of this relationship can have, as most of us probably instinctively know, negative effects.

Bowlby’s early approach involved the mother’s having an understanding of the formational experiences of her own childhood and then translating that to an understanding of her child. He even found that when he talked with parents about their own childhoods in front of their children, the result would be clinical breakthroughs for his patients. As he wrote,

Having once been helped to recognize and recapture the feelings which she herself had as a child and to find that they are accepted tolerantly and understandingly, a mother will become increasingly sympathetic and tolerant toward the same things in her child.

Later studies seem to bear out this observation of a connection to one’s childhood experiences and more connected parenting. For example, mothers who are “insightful” about their children, who seek to understand the motivations of their children’s behavior, positively influence both their own sensitivity and the security of their infant’s attachment to them.  

While Bowlby’s research focused initially on the effects of absolute separation between mother and child, Mary Ainsworth, an eventual colleague of Bowlby, took these ideas of the need for maternal input a step further. Her work suggested to her that young children live in a world of dual and competing urges: to feel safe and to be independent. An attachment figure, a safe person, is for children an anchor that keeps them from become unmoored even as they explore the unknown waters of life. Without that security backing them up, a child can feel always unmoored and directionless, with no one to trust for security.

Although he was considered an anti-Freudian rebel, Bowlby had a penchant for Freudian language like “superego” and referred to the mother as the “psychic organizer.” Yet his conclusions about the mother–child bond resonate with their plain language:

The infant and young child should experience a warm, intimate, and continuous relationship with his mother (or permanent mother substitute) in which both find satisfaction and enjoyment.

You know, normal biological stuff. As a side note, he was intrigued by the fact that social bonds between mother and offspring in some species weren’t necessarily tied to feeding, an observation worth keeping in mind if you have concerns about not being able to breastfeed.

The big shift here in talking about the mother–child relationship was that Bowlby was proposing that this connection wasn’t some Freudian libidinous communion between mother and child but instead a healthy foundation of a trust relationship that could healthily continue into the child’s adulthood.

Ainsworth carried these ideas to specifics, noting in the course of her observations of various groups how valuable a mother’s sensitivity to her child’s behaviors were in establishing attachment. In her most famous study, the “Baltimore study” [PDF], she monitored 26 families with new babies. She found that “maternal responsiveness” in the context of crying, feeding, playing, and reciprocating seemed to have a powerful influence on how much a baby cried in later months, although some later studies dispute specific influences on crying frequencies.

Ainsworth also introduced the “Strange Situation” lab test, which seems to have freaked people out when it first entered the research scene. In this test, over the course of 20 minutes, a one-year-old baby is in a room full toys, first with its mother, then with mother and a strange woman, then with the stranger only (briefly), then with the mother, and then alone before the stranger and then the mother return. The most interesting findings of the study came from when the mother returned after her first absence, having left the baby alone in the room with a stranger. Some babies seemed quite angry, wanting to be with their mothers but expressing unhappiness with her at the same time and physically rejecting her.

From her observations during the Strange Situation, Ainsworth identified three types of attachment. The first was “Secure,” which, as its name implies, suggested an infant secure and comfortable with an attachment figure, a person with whom the infant actively seeks to interact. Then there’s the insecure–avoidant attachment type, in which an infant clearly is not interested in being near or interacting with the attachment figure. Most complex seems to be the insecure–resistant type, and the ambivalence of the term reflects the disconnected behavior the infant shows, seeming to want to be near the attachment figure but also resisting, as some of the unhappy infants described above behaved in the Strange Situation.

Within these types are now embedded various subtypes, including a disorganized–disoriented type in which the infant shows “odd” and chaotic behavior that seems to have no distinct pattern related to the attachment figure.

As you read this, you may be wondering, “What kind of attachment do my child and I have?” If you’re sciencey, you may fleetingly even have pondered conducting your own Strange Situation en famille to see what your child does. I understand the impulse. But let’s read on.

What are the benefits of attachment?

Mothers who are sensitive to their children’s cues and respond in ways that are mutually satisfactory to both parties may be doing their children a lifetime of favors, in addition to the parental benefit of a possibly less-likely-to-cry child. For example, a study of almost 1300 families looked at levels of cortisol, the “stress” hormone, in six-month-old infants and its association with maternal sensitivity to cues and found lower levels in infants who had “more sensitive” mothers.

Our understanding of attachment and its importance to infant development can help in other contexts. We can apply this understanding to, for example, help adolescent mothers establish the “secure” level of attachment with their infants. It’s also possibly useful in helping women who are battling substance abuse to still establish a secure attachment with their children.

On a more individual level, it might help in other ways. For example, if you want your child to show less resistance during “clean-up” activities, establishing “secure attachment” may be your ticket to a better-looking playroom.

More seriously, another study has found that even the way a mother applies sensitivity can be relevant. Using the beautiful-if-technical term ‘dyads’ to refer to the mother–child pair, this study included maternal reports of infant temperament and observations of maternal sensitivity to both infant distress and “non-distress.” Further, the authors assessed the children behaviorally at ages 24 and 36 months for social competence, behavioral problems, and typicality of emotional expression. They found that a mother’s sensitivity to an infant’s distress behaviors was linked to fewer behavioral problems and greater social competence in toddlerhood. Even more intriguing, the child’s temperament played a role: for “temperamentally reactive” infants, a mother’s sensitivity to distress was linked to less dysregulation of the child’s emotional expression in toddlerhood. 


And that takes me to the child, the partner in the “dyad”

You’re not the only person involved in attachment. As these studies frequently note, you are involved in a “dyad.” The other member of that dyad is the child. As much as we’d like to think that we can lock down various aspects of temperament or expression simply by forcing it with our totally excellent attachment skills, the child in your dyad is a person, too, who arrived with a bit of baggage of her own.

And like the study described above, the child’s temperament is a key player in the outcome of the attachment tango. Another study noted that multiple factors influence “attachment quality.” Yes, maternal sensitivity is one, but a child’s native coping behaviors and temperament also seem to be involved. So, there you have it. If you’re feeling like a parental failure, science suggests you can quietly lay at least some of the blame on the Other in your dyad–your child. Or, you could acknowledge that we’re all human and this is just part of our learning experience together.

What does attachment look like, anyway?

Dr. William Sears took the concept of attachment and its association with maternal sensitivity to a child’s cues and security and… wrote a book that literally translated attachment as a physical as well as emotional connection. This extension of attachment–which Sears appends to every aspect of parenting, from pregnancy to feeding to sleeping–has become in the minds of some parents a prescriptive way of doing things with benefits that exclude all other parenting approaches or “philosophies.” It also involves the concept of “baby wearing,” which always brings up strange images in my mind and certainly takes outré fashion to a whole new level. In reality, it’s just a way people have carried babies for a long time in the absence of other easy modes of transport.

When I was pregnant with our first child and still blissfully ignorant about how little control parents have over anything, I read Sears’ book about attachment parenting. Some of it is common-sense, broadly applicable parenting advice: respond to your child’s needs. Some of it is simply downright impossible for some parent–child dyads, and much of it is based on the presumption that human infants in general will benefit from a one-size-fits-all sling of attachment parenting, although interpretations of the starry-eyed faithful emphasize that more than Sears does.

Because much of what Sears wrote resonated with me, we did some chimeric version of attachment parenting–or, we tried. The thing is, as I noted above, the infant has some say in these things as well. Our oldest child, who is autistic, was highly resistant to being physically attached much of the time. He didn’t want to sleep with us past age four months, and he showed little interest in aspects of attachment parenting like “nurturing touch,” which to him was seemingly more akin to “taser touch.” We ultimately had three sons, and in the end, they all preferred to sleep alone, each at an earlier and earlier age. The first two self-weaned before age one because apparently, the distractions of the sensory world around them were far more interesting than the same boring old boob they kept seeing immediately in front of their faces. Our third was unable to breastfeed at all.

So, like all parents do, we punted, in spite of our best laid plans and intentions. Our hybrid of “attachment parenting” could better be translated into “sensitivity parenting,” because our primary focus, as we punted and punted and punted our way through the years, was shifting our responses based on what our children seemed to need and what motivated their behaviors. Thus, while our oldest declined to sleep with us according to the attachment parenting commandment, he got to sleep with a boiled egg because that’s what he wanted. Try to beat that, folks, and sure, bring on the judging.

The Double X Science
Sensitivity Parenting (TM) cheat sheet.

What does “sensitive” mean?

And finally, the nitty-gritty bullet list you’ve been waiting for. If attachment doesn’t mean slinging your child to your body until you’re lumbar gives out or the child receives a high-school diploma, and parenting is, indeed, one compromise after another based on the exigencies of the moment, what consistent tenets can you practice that meet the now 60-year-old concept of “secure” attachment between mother and child, father and child, or mother or father figure and child? We are Double X Science, here to bring you evidence-based information, and that means lists. The below list is an aggregate of various research findings we’ve identified that seem reasonable and reasonably supported. We’ve also provided our usual handy quick guide for parents in a hurry.
  • Plan ahead. We know that life is what happens while you’re planning things, but… life does happen, and plans can at least serve as a loose guide to navigation. So, plan that you will be a parent who is sensitive to your child’s needs and will work to recognize them.
  • Practice emotion detection. Work on that. It doesn’t come easily to everyone because the past is prologue to what we’re capable of in the present. Ask yourself deliberately what your child’s emotion is communicating because behavior is communication. Be the grownup, even if sometimes, the wailing makes you want your mommy. As one study I found notes, “Crying is an aversive behavior.” Yes, maybe it makes you want to cover your ears and run away screaming. But you’re the grownup with the analytical tools at hand to ask “Why” and seek the answer.
  • Have infant-oriented goals. If you tend to orient your goals in your parent–child dyad toward a child-related benefit (relieve distress) rather than toward a parent-oriented goal (fitting your schedule in some way), research suggests that your dyad will be a much calmer and better mutually adapted dyad.
  • Trust yourself and keep trying. If your efforts to read your child’s feelings or respond to your child’s needs don’t work right away, don’t give up, don’t read Time magazine covers, and don’t listen to that little voice in your head saying you’re a bad parent or the voice in other people’s heads screaming that at you. Just keep trying. It’s all any of us can do, and we’re all going to screw this up here and there.
  • Practice behaviors that are supportive of an infant’s sensory needs. For example, positive inputs like a warm voice and smiling are considered more effective than a harsh voice or being physically intrusive. Put yourself in your child’s place and ask, How would that feel? That’s called empathy. 
  • Engage in reciprocation. Imitating back your infant’s voice or faces, or showing joint attention–all forms of joint engagement–are ways of telling an infant or young child that yes, you are the anchor here, the one to trust, and really good time, to boot. Allowing this type of attention to persist as long as the infant chooses rather than shifting away from it quickly is associated with making the child comfortable with independence and learning to regulate behaviors.  
  • Talk to your child. We are generally a chatty species, but we also need to learn to chat. “Rich language input” is important in early child development beginning with that early imitation of your infant’s vocalizations.
Lather, rinse, repeat, adjusting dosage as necessary based on age, weight, developmental status, nanosecond-rate changes in family dynamics and emotional conditions, the teen years, and whether or not you have access to chocolate. See? This stuff is easy.

                                                          

Finally

As you read these lists and about research on attachment, you’ll see words like “secure” and “warm” and “intimate” and “safe.” Are you doing this for your child or doing your best to do it? Then you are, indeed, mom enough, whether you wear your baby or those shoes or both. That doesn’t mean that when you tell other women the specifics of your parenting tactics, they won’t secretly be criticizing you. Sure, we’ll all do that. And then a toddler will cry, we’ll drop it, and move on to mutually compatible things.

Yes, if we’re being honest, it makes most of us feel better to think that somehow, in some way, we’re kicking someone else’s ass in the parenting department. Unfortunately for that lowly human instinct, we’re all parenting unique individuals, and while we may indeed kick ass uniquely for them, our techniques simply won’t extend to all other children. It’s not a war. It’s human… humans raising other humans. Not one thing we do, one philosophy we follow, will guarantee the outcome we intend. We don’t even need science, for once, to tell us that.


By Emily Willingham, DXS managing editor

These views are the opinion of the author and do not necessarily either reflect or disagree with those of the
DXS editorial team. 

What does ‘safe’ mean when we’re talking about chemicals?

It’s not easy being green. First, you have decide which green to be. (Source)

[We at Double X Science had been considering a "toxins" post but then found the following post by Jennifer Mo, a happily childfree vegetarian who lives in California with a cat named Brie but variously nicknamed Walnut "for her brain capacity" or Toxokitty for her history of toxoplasmosis--which, as it turns out, turns up in Jennifer's guest post, below. This post first appeared at Jennifer's blog, It's Not Easy to Be Green, where she writes about environmental issues as a "rationalist and a pragmatist." You can also follow Jennifer on Twitter @noteasy2begreen. We appreciated the pragmatics of this particular post quite a bit and thank Jennifer for allowing us to host it at Double X Science. We are particularly taken with the fact that she asks if we'd ever wanted to call our own brain a troglodyte.]

It’s a common demand from the public to scientists: prove to us something is safe before unleashing your monster on the world. And on one hand, it’s a totally fair, reasonable request to not be treated as lab rats. I get that. I hate the idea of having big chemical corporations profiting off their creations that create long term problems for ordinary people and the environment. On the other, whether you’re talking about GMOs or synthetic chemicals, it’s a problematic request for a couple of key reasons:
  • It assumes a binary between safe and unsafe without regard to exposure level or other circumstances. Just about everything can be harmful under the right (or perhaps I should say wrong?) conditions. Take water, for example.Tons Continue reading