Menus Subscribe Search

Follow us


Mother’s Travails May Appear in Offspring’s DNA

• February 18, 2009 • 2:00 PM

Puzzled over health complications more persistent among African Americans than in other Americans, researchers invoke epigenetics.

For years, scientists have wondered why African Americans die of cardiovascular disease and diabetes complications at much higher rates than European Americans. Despite advances in health care and living conditions, African Americans succumb to heart disease at a rate 1.3 times higher than that of whites.

But even after accounting for income differences and known risk factors, researchers find there is still an unexplained “racial” disparity.

Some scientists have argued that the difference must be due to some underlying genetic difference between races, while others contend that the cause is fundamentally social: low incomes, psychosocial stress and persistent racial discrimination give rise to chronic health problems that take their toll in higher mortality rates.

Recently, a third explanation has emerged. Some anthropologists now think the adverse social and physical conditions a mother faces while pregnant can change the way her developing fetus’s DNA is expressed, setting the stage for lifelong health problems.

Further, they argue, these deficits can actually be passed down through several generations, from grandmother to daughter to granddaughter in a phenomenon sometimes called “fetal programming.” A European researcher has even proposed that contemporary African Americans are still suffering health consequences from the extreme privations of slavery and in the pervasive discrimination following emancipation.

“A lot of research has jumped to the conclusion that anything that can’t be explained by the environment must relate back to the genome,” said Christopher Kuzawa, a Northwestern University anthropologist, who with colleague Elizabeth Sweet published a paper called, “Epigenetics and Embodiment of Race: Developmental Origins of US Racial Disparities in Cardiovascular Health” in the American Journal of Human Biology.

“I just don’t think the research supports that,” Kuzawa said. In fact, Kuzawa and Sweet don’t have much use for “race” itself as a biological concept. They write, “[W]e define race as a socially constructed category that has biological implications, rather than a genetically justified criteria for classifying human variation.”

Data show African-American children are born with lower birth weight on average than their European-American counterparts —and often somewhat preterm. “What has been shown is if you’re born with a low birth weight, you are at increased risk later in life for high blood pressure, diabetes and cardiovascular disease,” Kuzawa said.

The question is, why are African-American children more likely to be born underweight in the first place?

Kuzawa thinks it is due to the cumulative, transgenerational impacts of chronic social stress. Developmental biologists specializing in a field called epigenetics have shown that the genetic legacy encoded in our DNA doesn’t tell the whole story, he says. “What is modifiable is which of these genes is expressed,” he says. Kuzawa doesn’t deny the direct impact of racism and discrimination, which are bound to be stressful. “Stress is bad for you,” he said, and by itself, stress is implicated in problems like high blood pressure and cardiovascular disease.

“What’s new is the realization that when women experience this, especially when they’re pregnant, that it affects their children,” Kuzawa said. Stress and poor prenatal nutrition can lead to underweight babies by impairing the blood flow to the developing child and exposing them to the stress hormone cortisol. Scientists also know, for example, that individuals who were undernourished in the womb tend to have smaller kidneys and fewer nephrons, predisposing them to hypertension and renal failure.

Moreover, when an underweight child becomes a mother herself, she is more likely to suffer from hypertension and other problems that will hamper her unborn child’s development. “These findings suggest that the intrauterine environment experienced by one generation (the mother) can influence the intrauterine environment that she creates for her offspring, in theory helping perpetuate certain biological or metabolic states, albeit in a fading fashion, across multiple matrilineal generations,” Kuzawa and Sweet wrote.

Grazyna Jasienska, a reproductive ecologist specializing in women’s fertility at Jagiellonian University in Krakow, Poland, has taken these ideas a step further. She believes that the persistence of underweight African-American babies may have its roots in the conditions of slavery their ancestors endured from the 17th through the 19th centuries. In effect, African Americans continue to carry a biological burden as a result of slavery.

Jasienska’s paper, “Low Birth Weight of Contemporary African Americans: An Intergenerational Effect of Slavery?” also published in the American Journal of Human Biology, shares Kuzawa’s emphasis on the importance of maternal health to the developing fetus. She noted, for example, that studies of egg donations show that the child’s birth size is more closely correlated with the stature of the recipient than that of the donor.

She also acknowledges that contemporary living conditions play a powerful role in determining birth weight, but she points out that in comparison with low-income white women, low-income African-American women still have smaller babies. Poverty by itself does not fully explain the differences, she found. Jasienska decided to look further back in time.

“African Americans have a long, multigenerational history of nutritional deprivation, excessive workloads, and poor health due to years of slavery and the postslavery period of economic hardship,” she wrote.

Combing through historical data, Jasienska found that 84 percent of slave children began working before the age of 11. Their heights, preserved in slave ship records, suggests that they suffered from terrible nutrition, she said. Meanwhile, slave women often did strenuous work in the fields while pregnant, placing further stresses on their unborn offspring. Nor did things improve in the decades after slavery was outlawed. “Some people say former slaves in fact became worse off with the share-cropping system,” Jazienska said.

Like Kuzawa, Jasienska dismisses racial explanations for contemporary differences in birth weight. Because most African Americans trace their ancestry to West Africa, one would expect that if a racial difference was at work West African women would also have underweight children, but that isn’t the case. “When they come to the United States, they have babies with much higher birth weight than African Americans,” Jasienska said.

Jasienska acknowledges it’s hard to verify this hypothesis. “Fortunately, slavery is gone, so it’s hard to get data on calories that were expended.”

Kuzawa, meanwhile, says the slavery theory is “very provocative and interesting,” but still thinks the pervasiveness of racism in our society goes a long way to explain these health differences. “The overarching punch line of this work is that it’s emphasizing the primacy of environmental impacts,” he said. “It’s good news, in the sense that you can change the environment — you can’t change the genome.”

But he added, “I don’t think there is going to be a quick fix here . . . If we want to improve the health of future generations, we need to start working now.”

Sign up for our free e-newsletter.

Are you on Facebook? Become our fan.

Add our news to your site.

Michael Haederle
Michael Haederle lives in New Mexico. He has written for the Los Angeles Times, People Magazine, Tricycle: The Buddhist Review and many other publications. He has also taught at Syracuse University's S.I. Newhouse School of Public Communications and is a Zen lay monk.

More From Michael Haederle

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

Recent Posts

October 20 • 2:00 PM

The Risk of Getting Killed by the Police If You Are White, and If You Are Black

An analysis of killings by police shows outsize risk for young black males.


October 20 • 12:00 PM

Love and Hate in Israel and Palestine

Psychologists find that parties to a conflict think they’re motivated by love while their enemies are motivated by hate.


October 20 • 11:00 AM

My Dog Comes First: The Importance of Pets to Homeless Youth

Dogs and cats have both advantages and disadvantages for street-involved youth.


October 20 • 10:00 AM

Homophobia Is Not a Thing of the Past

Despite growing support for LGBT rights and recent decisions from the Supreme Court regarding the legality of same-sex marriage, the battle for acceptance has not yet been decided.


October 20 • 8:00 AM

Big Boobs Matter Most

Medical mnemonics are often scandalous and sexist, but they help the student to both remember important facts and cope with challenging new experiences.


October 20 • 6:00 AM

When Disease Becomes Political: The Likely Electoral Fallout From Ebola

Will voters blame President Obama—and punish Democrats in the upcoming mid-term elections—for a climate of fear?


October 20 • 4:00 AM

Coming Soon: The Anatomy of Ignorance


October 17 • 4:00 PM

What All Military Families Need to Know About High-Cost Lenders

Lessons from over a year on the beat.


October 17 • 2:00 PM

The Majority of Languages Do Not Have Gendered Pronouns

A world without “he.” Or “she.”


October 17 • 11:01 AM

How to Water a Farm in Sandy Ground

Physicists investigate how to grow food more efficiently in fine-grained soil.


October 17 • 10:00 AM

Can Science Fiction Spur Science Innovation?

Without proper funding, the answer might not even matter.


October 17 • 8:00 AM

Seattle, the Incredible Shrinking City

Seattle is leading the way in the micro-housing movement as an affordable alternative to high-cost city living.


October 17 • 6:00 AM

‘Voodoo Death’ and How the Mind Harms the Body

Can an intense belief that you’re about to die actually kill you? Researchers are learning more about “voodoo death” and how it isn’t limited to superstitious, foreign cultures.


October 17 • 4:00 AM

That Arts Degree Is Paying Off

A survey of people who have earned degrees in the arts find they are doing relatively well, although their education didn’t provide much guidance on managing a career.


October 16 • 4:00 PM

How (Some) Economists Are Like Doomsday Cult Members

Cognitive dissonance and clinging to paradigms even in the face of accumulated anomalous facts.


October 16 • 2:00 PM

The Latest—and Most Mysterious—Player in the Nasty Battle Over Net Neutrality

As the FCC considers how to regulate Internet providers, the telecom industry’s stealth campaign for hearts and minds encompasses everything from art installations to LOLcats.


October 16 • 12:00 PM

How Many Ads Is Too Many Ads?

The conundrum of online video advertising.


October 16 • 11:00 AM

Unlocking Consciousness

A study of vegetative patients closes in on the nature of consciousness.


October 16 • 10:00 AM

The False Promises of Higher Education

Danielle Henderson spent six years and $60,000 on college and beyond. The effects of that education? Not as advertised.


October 16 • 8:00 AM

Faster Justice, Closer to Home: The Power of Community Courts

Community courts across the country are fighting judicial backlog and lowering re-arrest rates.


October 16 • 6:00 AM

Killing Your Husband to Save Yourself

Without proper legal instruments, women with abusive partners are often forced to make a difficult choice: kill or be killed.


October 16 • 4:00 AM

Personality Traits Linked to Specific Diseases

New research finds neurotic people are more likely to suffer a serious health problem.


October 16 • 2:00 AM

Comparing Apples to the Big Apple: Yes, Washington, D.C., Is More Expensive Than New York City

Why shouldn’t distant locales tied to jobs in the urban core count in a housing expenditure study?


October 15 • 4:00 PM

Why Asian American Parents Are the Least Likely to Spank Their Kids

Highly educated, middle-class parents are less likely to use corporal punishment to discipline their children than less-educated, working-class, and poor parents.


October 15 • 2:00 PM

The Federal Government’s New Doctor Payments Website Is Worthy of a Recall

Charles Ornstein takes a test drive using the federal government’s new website for drug and device payments and finds it virtually unusable.


Follow us


Love and Hate in Israel and Palestine

Psychologists find that parties to a conflict think they're motivated by love while their enemies are motivated by hate.

How to Water a Farm in Sandy Ground

Physicists investigate how to grow food more efficiently in fine-grained soil.

Unlocking Consciousness

A study of vegetative patients closes in on the nature of consciousness.

Advice for Emergency Alert Systems: Don’t Cry Wolf

A survey finds college students don't always take alerts seriously.

Brain’s Reward Center Does More Than Manage Rewards

Nucleus accumbens tracks many different connections in the world, a new rat study suggests.

The Big One

One company, Amazon, controls 67 percent of the e-book market in the United States—down from 90 percent five years ago. September/October 2014 new-big-one-5

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