Menus Subscribe Search

Follow us


Genes Are Us

book-math

(Photo: Syda Productions/Shutterstock)

How and Why Does the Social Become Biological?

• August 01, 2014 • 4:00 AM

(Photo: Syda Productions/Shutterstock)

To get closer to an answer, it’s helpful to look at two things we’ve taught ourselves over time: reading and math.

Every Friday this month we’ll be taking a look at the relationship between the social and the biological—specifically, how and why the former becomes the latter. Check back each week for a new installment.

It’s one of the most irresistible and controversial questions in science: “How and why does the social become biological?” The classic mind-body split is something we feel intuitively, a distinction between our “biology”—our anatomy or our physical health—and our social, decision-making minds. So it can be jarring to hear claims like this: “People differ in their intelligence, personality, and behavior, and a century of research in behavioral genetics leaves little doubt that some of this variation is caused by differences in their genomes.” No matter where we look, we always find the influence of genetics—the social is never entirely free of the biological. But what does it really mean to say that social or mental traits are influenced by genes?

Consider two traits that didn’t evolve “naturally,” but rather were completely invented by humans: the ability to read and do mathematics. Last month, a consortium of scientists sponsored by the Wellcome Trust published a study showing that “the correlation between reading and mathematics ability at age twelve has a substantial genetic component.” In other words, reading and math abilities aren’t merely the result of a decision to work hard at them, or an opportunity to learn; they also depend on DNA.

Genetic distinctions affect every chemical process in our cells, and because absolutely nothing we do happens without some cell chemistry, everything about us is potentially influenced by genetic variation.

In one sense, this is trivially obvious. The reason that children learn to read and chimpanzees don’t has nothing to do with the chimps’ lack of educational opportunities; it’s entirely genetic. The physical nature of our brains allows us to develop mental skills that are hopelessly out of reach for other animals.

But when we say a mental trait is influenced by genetics, we clearly mean more than that; we’re also making a statement about the role of genetic differences among people. Learning to read and do math involves some very complex brain biology. New links are made between different specialized areas of the brain, and old parts are re-purposed to engage in something that human brains didn’t do until relatively recently. All of this brain rewiring depends intimately on the chemistry of our neural cells, chemistry that is subtly altered by thousands of genetic differences that change the properties of the molecules involved. Unlike the precision engineering that goes into the latest Intel chip, the human brain’s process tolerances are rather wide—nearly all of our molecular parts show some variation among the human population.

Genetic variation is an unavoidable and central fact of biology, and it is at the heart of the relationship between the social and the biological. There never was a master copy of the human genome; species nearly always exist as populations of genetically varied individuals. These genetic distinctions affect every chemical process in our cells, and because absolutely nothing we do happens without some cell chemistry, everything about us is potentially influenced by genetic variation.

The Wellcome Trust researchers studied the influence of genetic variation on math and reading skills, and the correlation between them. Using data collected from nearly 3,000 sets of twins who had taken standard reading and math tests, they used two methods to examine the role of genetics.

In the first method, they searched directly for an association between a specific DNA difference and scores on tests for math or reading. The idea behind this is fairly simple: Consider a place in the human genome where people differ—some people may have the chemical letter “A,” while others have “G.” Do people with an “A” have, on average, higher test scores than those with a “G?” You repeat this test for thousands or millions of different places in the genome and find the DNA differences with the strongest association. In practice, scientists don’t merely compare the averages of “A” versus “G”; they use a more powerful statistical procedure, but the point is the same: to find specific genetic variants that correlate with differences in test scores.

The second approach, using the resemblance between twins, is more indirect—it doesn’t involve knowing any of the actual DNA differences involved. Since twins share a common family environment, but identical twins are closer genetically than fraternal twins, it’s possible to quantify the genetic and environmental influences on a trait without saying specifically what those influences are.

From these analyses, the researchers came away with three big results that nicely illustrate what it means to say that a behavioral or mental trait has a genetic component. First, the twin analysis showed that genetics explains many of the differences in reading and math test scores in the studied population. But the researchers were unable to find any reproducible association between any specific DNA difference and reading and math ability, suggesting that the total genetic effect is the cumulative result of small changes in many different genes. And finally, they found that not only were reading and math scores influenced by genetics, but also that the correlation between reading and math scores showed a strong genetic influence, suggesting that these skills are influenced by “generalist genes.”

What is a “generalist gene”? The idea, proposed years ago by Robert Plomin, one of the study authors, and Yulia Kovas, is that many of the genes involved in cognitive processes don’t have highly specialized roles limited to one part of the brain. Instead, each generalist gene influences many different brain processes, and conversely, each brain process is the combined result of many different genes. Hence, common genetic variation in any one gene will have only a small effect, but on many different traits at the same time.

Importantly, genetic studies like this one also say something about the importance of the environment. The authors argue that “our results highlight the potential role of the learning environment in contributing to differences in a child’s cognitive abilities at age twelve.” They’re suggesting that when a child’s reading and math abilities—which should be correlated—diverge from each other, there is an opportunity to make a productive change in the learning environment.

Genetic variation influences every cellular process, and everything we do depends in some way on the processes in our cells; ultimately, the social and the biological are inseparable.

Michael White
Michael White is a systems biologist at the Department of Genetics and the Center for Genome Sciences and Systems Biology at the Washington University School of Medicine in St. Louis, where he studies how DNA encodes information for gene regulation. He co-founded the online science pub The Finch and Pea. Follow him on Twitter @genologos.

More From Michael White

A weekly roundup of the best of Pacific Standard and PSmag.com, delivered straight to your inbox.

Recent Posts

October 31 • 12:00 PM

In the Picture: SNAP Food Benefits, Birthday Cake, and Walmart

In every issue, we fix our gaze on an everyday photograph and chase down facts about details in the frame.


October 31 • 10:15 AM

Levels of Depression Could Be Evaluated Through Measurements of Acoustic Speech

Engineers find tell-tale signs in speech patterns of the depressed.


October 31 • 8:00 AM

Who Wants a Cute Congressman?

You probably do—even if you won’t admit it. In politics, looks aren’t everything, but they’re definitely something.


October 31 • 7:00 AM

Why Scientists Make Promises They Can’t Keep

A research proposal that is totally upfront about the uncertainty of the scientific process and its potential benefits might never pass governmental muster.


October 31 • 6:12 AM

The Psychology of a Horror Movie Fan

Scientists have tried to figure out the appeal of axe murderers and creepy dolls, but it mostly remains a spooky mystery.


October 31 • 4:00 AM

The Power of Third Person Plural on Support for Public Policies

Researchers find citizens react differently to policy proposals when they’re framed as impacting “people,” as opposed to “you.”


October 30 • 4:00 PM

I Should Have Told My High School Students About My Struggle With Drinking

As a teacher, my students confided in me about many harrowing aspects of their lives. I never crossed the line and shared my biggest problem with them—but now I wish I had.


October 30 • 2:00 PM

How Dark Money Got a Mining Company Everything It Wanted

An accidentally released court filing reveals how one company secretly gave money to a non-profit that helped get favorable mining legislation passed.


October 30 • 12:00 PM

The Halloween Industrial Complex

The scariest thing about Halloween might be just how seriously we take it. For this week’s holiday, Americans of all ages will spend more than $5 billion on disposable costumes and bite-size candy.


October 30 • 10:00 AM

Sky’s the Limit: The Case for Selling Air Rights

Lower taxes and debt, increased revenue for the city, and a much better use of space in already dense environments: Selling air rights and encouraging upward growth seem like no-brainers, but NIMBY resistance and philosophical barriers remain.


October 30 • 9:00 AM

Cycles of Fear and Bias in the Criminal Justice System

Exploring the psychological roots of racial disparity in U.S. prisons.


October 30 • 8:00 AM

How Do You Make a Living, Email Newsletter Writer?

Noah Davis talks to Wait But Why writer Tim Urban about the newsletter concept, the research process, and escaping “money-flushing toilet” status.



October 30 • 6:00 AM

Dreamers of the Carbon-Free Dream

Can California go full-renewable?


October 30 • 5:08 AM

We’re Not So Great at Rejecting Each Other

And it’s probably something we should work on.


October 30 • 4:00 AM

He’s Definitely a Liberal—Just Check Out His Brain Scan

New research finds political ideology can be easily determined by examining how one’s brain reacts to disgusting images.


October 29 • 4:00 PM

Should We Prosecute Climate Change Protesters Who Break the Law?

A conversation with Bristol County, Massachusetts, District Attorney Sam Sutter, who dropped steep charges against two climate change protesters.


October 29 • 2:23 PM

Innovation Geography: The Beginning of the End for Silicon Valley

Will a lack of affordable housing hinder the growth of creative start-ups?


October 29 • 2:00 PM

Trapped in the Tobacco Debt Trap

A refinance of Niagara County, New York’s tobacco bonds was good news—but for investors, not taxpayers.


October 29 • 12:00 PM

Purity and Self-Mutilation in Thailand

During the nine-day Phuket Vegetarian Festival, a group of chosen ones known as the mah song torture themselves in order to redirect bad luck and misfortune away from their communities and ensure a year of prosperity.


October 29 • 10:00 AM

Can Proposition 47 Solve California’s Problem With Mass Incarceration?

Reducing penalties for low-level felonies could be the next step in rolling back draconian sentencing laws and addressing the criminal justice system’s long legacy of racism.


October 29 • 9:00 AM

Chronic Fatigue Syndrome and the Brain

Neuroscientists find less—but potentially stronger—white matter in the brains of patients with CFS.


October 29 • 8:00 AM

America’s Bathrooms Are a Total Failure

No matter which American bathroom is crowned in this year’s America’s Best Restroom contest, it will still have a host of terrible flaws.



October 29 • 6:00 AM

Tell Us What You Really Think

In politics, are we always just looking out for No. 1?


Follow us


Levels of Depression Could Be Evaluated Through Measurements of Acoustic Speech

Engineers find tell-tale signs in speech patterns of the depressed.

We’re Not So Great at Rejecting Each Other

And it's probably something we should work on.

Chronic Fatigue Syndrome and the Brain

Neuroscientists find less—but potentially stronger—white matter in the brains of patients with CFS.

Incumbents, Pray for Rain

Come next Tuesday, rain could push voters toward safer, more predictable candidates.

Could Economics Benefit From Computer Science Thinking?

Computational complexity could offer new insight into old ideas in biology and, yes, even the dismal science.

The Big One

One town, Champlain, New York, was the source of nearly half the scams targeting small businesses in the United States last year. November/December 2014

Copyright © 2014 by Pacific Standard and The Miller-McCune Center for Research, Media, and Public Policy. All Rights Reserved.