Genetics and Race

Credit Angie Wang

In 1942, the anthropologist Ashley Montagu published “Man’s Most Dangerous Myth: The Fallacy of Race,” an influential book that argued that race is a social concept with no genetic basis. A classic example often cited is the inconsistent definition of “black.” In the United States, historically, a person is “black” if he has any sub-Saharan African ancestry; in Brazil, a person is not “black” if he is known to have any European ancestry. If “black” refers to different people in different contexts, how can there be any genetic basis to it?

Beginning in 1972, genetic findings began to be incorporated into this argument. That year, the geneticist Richard Lewontin published an important study of variation in protein types in blood. He grouped the human populations he analyzed into seven “races” — West Eurasians, Africans, East Asians, South Asians, Native Americans, Oceanians and Australians — and found that around 85 percent of variation in the protein types could be accounted for by variation within populations and “races,” and only 15 percent by variation across them. To the extent that there was variation among humans, he concluded, most of it was because of “differences between individuals.”

In this way, a consensus was established that among human populations there are no differences large enough to support the concept of “biological race.” Instead, it was argued, race is a “social construct,” a way of categorizing people that changes over time and across countries.

It is true that race is a social construct. It is also true, as Dr. Lewontin wrote, that human populations “are remarkably similar to each other” from a genetic point of view.

But over the years this consensus has morphed, seemingly without questioning, into an orthodoxy. The orthodoxy maintains that the average genetic differences among people grouped according to today’s racial terms are so trivial when it comes to any meaningful biological traits that those differences can be ignored.

The orthodoxy goes further, holding that we should be anxious about any research into genetic differences among populations. The concern is that such research, no matter how well-intentioned, is located on a slippery slope that leads to the kinds of pseudoscientific arguments about biological difference that were used in the past to try to justify the slave trade, the eugenics movement and the Nazis’ murder of six million Jews.

I have deep sympathy for the concern that genetic discoveries could be misused to justify racism. But as a geneticist I also know that it is simply no longer possible to ignore average genetic differences among “races.”

Groundbreaking advances in DNA sequencing technology have been made over the last two decades. These advances enable us to measure with exquisite accuracy what fraction of an individual’s genetic ancestry traces back to, say, West Africa 500 years ago — before the mixing in the Americas of the West African and European gene pools that were almost completely isolated for the last 70,000 years. With the help of these tools, we are learning that while race may be a social construct, differences in genetic ancestry that happen to correlate to many of today’s racial constructs are real.

Recent genetic studies have demonstrated differences across populations not just in the genetic determinants of simple traits such as skin color, but also in more complex traits like bodily dimensions and susceptibility to diseases. For example, we now know that genetic factors help explain why northern Europeans are taller on average than southern Europeans, why multiple sclerosis is more common in European-Americans than in African-Americans, and why the reverse is true for end-stage kidney disease.

I am worried that well-meaning people who deny the possibility of substantial biological differences among human populations are digging themselves into an indefensible position, one that will not survive the onslaught of science. I am also worried that whatever discoveries are made — and we truly have no idea yet what they will be — will be cited as “scientific proof” that racist prejudices and agendas have been correct all along, and that those well-meaning people will not understand the science well enough to push back against these claims.

This is why it is important, even urgent, that we develop a candid and scientifically up-to-date way of discussing any such differences, instead of sticking our heads in the sand and being caught unprepared when they are found.

To get a sense of what modern genetic research into average biological differences across populations looks like, consider an example from my own work. Beginning around 2003, I began exploring whether the population mixture that has occurred in the last few hundred years in the Americas could be leveraged to find risk factors for prostate cancer, a disease that occurs 1.7 times more often in self-identified African-Americans than in self-identified European-Americans. This disparity had not been possible to explain based on dietary and environmental differences, suggesting that genetic factors might play a role.

Self-identified African-Americans turn out to derive, on average, about 80 percent of their genetic ancestry from enslaved Africans brought to America between the 16th and 19th centuries. My colleagues and I searched, in 1,597 African-American men with prostate cancer, for locations in the genome where the fraction of genes contributed by West African ancestors was larger than it was elsewhere in the genome. In 2006, we found exactly what we were looking for: a location in the genome with about 2.8 percent more African ancestry than the average.

When we looked in more detail, we found that this region contained at least seven independent risk factors for prostate cancer, all more common in West Africans. Our findings could fully account for the higher rate of prostate cancer in African-Americans than in European-Americans. We could conclude this because African-Americans who happen to have entirely European ancestry in this small section of their genomes had about the same risk for prostate cancer as random Europeans.

Did this research rely on terms like “African-American” and “European-American” that are socially constructed, and did it label segments of the genome as being probably “West African” or “European” in origin? Yes. Did this research identify real risk factors for disease that differ in frequency across those populations, leading to discoveries with the potential to improve health and save lives? Yes.

While most people will agree that finding a genetic explanation for an elevated rate of disease is important, they often draw the line there. Finding genetic influences on a propensity for disease is one thing, they argue, but looking for such influences on behavior and cognition is another.

But whether we like it or not, that line has already been crossed. A recent study led by the economist Daniel Benjamin compiled information on the number of years of education from more than 400,000 people, almost all of whom were of European ancestry. After controlling for differences in socioeconomic background, he and his colleagues identified 74 genetic variations that are over-represented in genes known to be important in neurological development, each of which is incontrovertibly more common in Europeans with more years of education than in Europeans with fewer years of education.

It is not yet clear how these genetic variations operate. A follow-up study of Icelanders led by the geneticist Augustine Kong showed that these genetic variations also nudge people who carry them to delay having children. So these variations may be explaining longer times at school by affecting a behavior that has nothing to do with intelligence.

This study has been joined by others finding genetic predictors of behavior. One of these, led by the geneticist Danielle Posthuma, studied more than 70,000 people and found genetic variations in more than 20 genes that were predictive of performance on intelligence tests.

Is performance on an intelligence test or the number of years of school a person attends shaped by the way a person is brought up? Of course. But does it measure something having to do with some aspect of behavior or cognition? Almost certainly. And since all traits influenced by genetics are expected to differ across populations (because the frequencies of genetic variations are rarely exactly the same across populations), the genetic influences on behavior and cognition will differ across populations, too.

You will sometimes hear that any biological differences among populations are likely to be small, because humans have diverged too recently from common ancestors for substantial differences to have arisen under the pressure of natural selection. This is not true. The ancestors of East Asians, Europeans, West Africans and Australians were, until recently, almost completely isolated from one another for 40,000 years or longer, which is more than sufficient time for the forces of evolution to work. Indeed, the study led by Dr. Kong showed that in Iceland, there has been measurable genetic selection against the genetic variations that predict more years of education in that population just within the last century.

To understand why it is so dangerous for geneticists and anthropologists to simply repeat the old consensus about human population differences, consider what kinds of voices are filling the void that our silence is creating. Nicholas Wade, a longtime science journalist for The New York Times, rightly notes in his 2014 book, “A Troublesome Inheritance: Genes, Race and Human History,” that modern research is challenging our thinking about the nature of human population differences. But he goes on to make the unfounded and irresponsible claim that this research is suggesting that genetic factors explain traditional stereotypes.

One of Mr. Wade’s key sources, for example, is the anthropologist Henry Harpending, who has asserted that people of sub-Saharan African ancestry have no propensity to work when they don’t have to because, he claims, they did not go through the type of natural selection for hard work in the last thousands of years that some Eurasians did. There is simply no scientific evidence to support this statement. Indeed, as 139 geneticists (including myself) pointed out in a letter to The New York Times about Mr. Wade’s book, there is no genetic evidence to back up any of the racist stereotypes he promotes.

Another high-profile example is James Watson, the scientist who in 1953 co-discovered the structure of DNA, and who was forced to retire as head of the Cold Spring Harbor Laboratories in 2007 after he stated in an interview — without any scientific evidence — that research has suggested that genetic factors contribute to lower intelligence in Africans than in Europeans.

At a meeting a few years later, Dr. Watson said to me and my fellow geneticist Beth Shapiro something to the effect of “When are you guys going to figure out why it is that you Jews are so much smarter than everyone else?” He asserted that Jews were high achievers because of genetic advantages conferred by thousands of years of natural selection to be scholars, and that East Asian students tended to be conformist because of selection for conformity in ancient Chinese society. (Contacted recently, Dr. Watson denied having made these statements, maintaining that they do not represent his views; Dr. Shapiro said that her recollection matched mine.)

What makes Dr. Watson’s and Mr. Wade’s statements so insidious is that they start with the accurate observation that many academics are implausibly denying the possibility of average genetic differences among human populations, and then end with a claim — backed by no evidence — that they know what those differences are and that they correspond to racist stereotypes. They use the reluctance of the academic community to openly discuss these fraught issues to provide rhetorical cover for hateful ideas and old racist canards.

This is why knowledgeable scientists must speak out. If we abstain from laying out a rational framework for discussing differences among populations, we risk losing the trust of the public and we actively contribute to the distrust of expertise that is now so prevalent. We leave a vacuum that gets filled by pseudoscience, an outcome that is far worse than anything we could achieve by talking openly.

If scientists can be confident of anything, it is that whatever we currently believe about the genetic nature of differences among populations is most likely wrong. For example, my laboratory discovered in 2016, based on our sequencing of ancient human genomes, that “whites” are not derived from a population that existed from time immemorial, as some people believe. Instead, “whites” represent a mixture of four ancient populations that lived 10,000 years ago and were each as different from one another as Europeans and East Asians are today.

So how should we prepare for the likelihood that in the coming years, genetic studies will show that many traits are influenced by genetic variations, and that these traits will differ on average across human populations? It will be impossible — indeed, anti-scientific, foolish and absurd — to deny those differences.

For me, a natural response to the challenge is to learn from the example of the biological differences that exist between males and females. The differences between the sexes are far more profound than those that exist among human populations, reflecting more than 100 million years of evolution and adaptation. Males and females differ by huge tracts of genetic material — a Y chromosome that males have and that females don’t, and a second X chromosome that females have and males don’t.

Most everyone accepts that the biological differences between males and females are profound. In addition to anatomical differences, men and women exhibit average differences in size and physical strength. (There are also average differences in temperament and behavior, though there are important unresolved questions about the extent to which these differences are influenced by social expectations and upbringing.)

How do we accommodate the biological differences between men and women? I think the answer is obvious: We should both recognize that genetic differences between males and females exist and we should accord each sex the same freedoms and opportunities regardless of those differences.

It is clear from the inequities that persist between women and men in our society that fulfilling these aspirations in practice is a challenge. Yet conceptually it is straightforward. And if this is the case with men and women, then it is surely the case with whatever differences we may find among human populations, the great majority of which will be far less profound.

An abiding challenge for our civilization is to treat each human being as an individual and to empower all people, regardless of what hand they are dealt from the deck of life. Compared with the enormous differences that exist among individuals, differences among populations are on average many times smaller, so it should be only a modest challenge to accommodate a reality in which the average genetic contributions to human traits differ.

It is important to face whatever science will reveal without prejudging the outcome and with the confidence that we can be mature enough to handle any findings. Arguing that no substantial differences among human populations are possible will only invite the racist misuse of genetics that we wish to avoid.

Medical Monday

Medical Monday – August 8, 2016

Medical 7-18-16Medical Monday is a service of Project RACE for the multiracial community. We seek, gather, and list health articles of interest to interracial families and people of all races. We welcome health information from outside sources as long as the original source is cited.

1.   Minorities less likely to have knee replacement surgery, more likely to have complications


American Academy of Orthopaedic Surgeons



  1. Morphology and Prevalence Study of Lumbar Scoliosis in 7,075 Multiracial Asian Adults


The Journal of Bone and Joint Surgery

3.     Diversity in the Ophthalmologist Workforce

Source:  JAMA ophthalmology


If you have current medical news to contribute, please email it with the source and your contact information with MEDICAL NEWS SUBMISSION in the subject line to:

Medical Monday

Diabetes, Hypertension Drive Higher CVD Risk in Blacks and Women

Frontline Medical News, 2014 Aug 12, A Karon


Risk factors for cardiovascular disease have disproportionately affected women and blacks, and while the gender gap has narrowed over time, black-white disparities have widened, reported authors of a large 10-year cohort study published Aug. 11 in the journal Circulation.

The study showed that factors such as high cholesterol and smoking account for less cardiovascular disease (CVD) risk than in the past, said Dr. Susan Cheng of Harvard Medical School in Boston and her associates. “However, the combined contribution of all traditional risk factors has remained substantially higher in women, compared with men, and in blacks, compared with whites,” the investigators said. “These sex- and race-based differences continue to be especially pronounced for hypertension and diabetes mellitus.”

The researchers calculated the population-attributable risks (PARs) of five major modifiable risk factors – smoking, hypercholesterolemia, hypertension, diabetes, and obesity – for the 10-year incidence of CVD among 13,541 participants in the Atherosclerosis Risk in Communities (ARIC) study. The cohort was 56% female, 26% black, and aged 52-66 years when examined during the time periods 1987-1989, 1990-1992, or 1996-1998, the investigators said (Circulation 2014 Aug. 11 [doi:10.1161/circulationaha.113.008506]).

The contribution of smoking and high cholesterol to CVD risk fell, (from 0.15 to 0.13 and from 0.18 to 0.09, respectively) during the study period, and the contribution of obesity stayed the same at 0.06, the researchers reported.

But by 1996-1998, diabetes mellitus accounted for significantly more CVD risk in blacks than whites (0.28 vs. 0.13), and the same was true for hypertension (0.36 vs. 0.21; P = .08) and all risk factors combined (0.67 vs. 0.48; P = .002), the researchers said. Similarly, PARs for women surpassed those for men for diabetes (0.21 vs. 0.14; P less than .0001) and hypertension (0.32 vs. 0.19; P = .02), they reported.

The racial differences suggest that prevention efforts based on traditional risk factors have benefited whites more than blacks, the researchers added. However, most blacks in the study were from the ARIC study center located in Jackson, Miss., so the race-based findings might be specific to that area, they noted.

“The reasons for persistent sex differences in attributable CVD risks over time are not yet clear,” said Dr. Cheng and associates. They added that sex-based differences could stem from clustering; underrecognition or undertreatment of risk factors in women; biological differences that are not yet understood; or nontraditional risk factors in men.

The National Heart, Lung, and Blood Institute funded the study. Dr. Cheng also received funding from the Ellison Foundation. The authors reported no conflicts of interest.

Source: Frontline Medical News

Medical Monday

Thyroid disease risk varies among blacks, Asians, whites

The JAMA Network Journals

An analysis that included active military personnel finds that the rate of the thyroid disorder Graves disease is more common among blacks and Asian/Pacific Islanders compared with whites, according to a study in the April 16 issue of JAMA.

Donald S. A. McLeod, F.R.A.C.P., M.P.H., of the QIMR Berghofer Medical Research Institute, Queensland, Australia and colleagues studied all U.S. active duty military, ages 20 to 54 years, from January 1997 to December 2011 to determine the rate of Graves disease and Hashimoto thyroiditis (a progressive autoimmune disease of the thyroid gland) by race/ethnicity. Cases were identified from data in the Defense Medical Surveillance System, which maintains comprehensive records of inpatient and outpatient medical diagnoses among all active-duty military personnel. The relationship between Graves disease and race/ethnicity has previously not been known.

During the study period there were 1,378 cases of Graves disease in women and 1,388 cases in men and 758 cases of Hashimoto thyroiditis in women and 548 cases in men. Compared with whites, the incident rates for Graves disease was significantly higher among blacks and Asian/Pacific Islanders. In contrast, Hashimoto thyroiditis incidence was highest in whites and lowest in blacks and Asian/Pacific Islanders.

The authors write that the differences in incidence by race/ethnicity found in this study may be due to different environmental exposures, genetics, or a combination of both.

Story Source:

The above story is based on materials provided by The JAMA Network JournalsNote: Materials may be edited for content and length. Additional source: Science Daily.

Journal Reference:

  1. Donald S. A. McLeod, Patrizio Caturegli, David S. Cooper, Peter G. Matos, Susan Hutfless. Variation in Rates of Autoimmune Thyroid Disease by Race/Ethnicity in US Military PersonnelJAMA, 2014; 311 (15): 1563 DOI: 10.1001/jama.2013.285606

Medical Monday

Single letter of DNA ‘defines hair color’

Changing just one letter of genetic code is enough to generate blonde hair in humans, according to a new analysis from researchers at the Howard Hughes Medical Institute in Chevy Chase, MD.

David Kingsley, of the Howard Hughes Medical Institute, has been studying the evolution of sticklebacks – the small fish that moved from the seas to colonize lakes and streams at the end of the last Ice Age – for the last 10 years.

Using the sticklebacks’ adaptive responses to different habitats as a case study, Kingsley and his colleagues have been able to identify molecular-level changes responsible for driving evolution. More recently, they have turned their attention to see how evolutions in the stickleback might apply to other species, such as humans.

The research that led Kingsley’s team to investigate the genetic code responsible for hair color initially concerned changes in stickleback pigmentation. As part of a 2007 study, they found that a change in the same gene had driven pigmentation changes in different populations of sticklebacks around the world.

Interestingly, they found that this genetic change was not unique to the stickleback.

Same gene in sticklebacks and humans controls pigmentation

“The very same gene that we found controlling skin color in fish showed one of the strongest signatures of selection in different human populations around the world,” Kingsley says.

magnifying glass and DNA
The genome “is littered with switches,” the researchers suspect.

Different versions of this gene – called “Kit ligand” – in humans are associated with differences in skin color. In both fish and humans, Kingsley found, the genetic changes thought to be responsible for pigmentation differences take place in regulatory elements of the genome.

“It looked like regulatory mutations in both fish and humans were changing pigment,” Kingsley says.

But tracking down specific regulatory elements in the whole genome is like finding a needle in the proverbial haystack. “We have to be kind of choosy about which regulatory elements we decide to zoom in on,” Kingsley acknowledges.

As well as encoding a protein that develops pigment-producing cells, however, Kit ligand has many other functions. For example, it influences the behaviors of blood stem cells, sperm or egg precursors and neurons in the intestine.

The team was interested in seeing whether they could isolate the regulatory changes in Kit ligand responsible for hair color without affecting any of the gene’s other functions.

‘Switching on’ Kit ligand’s hair color-determining powers

To do this, a research specialist in Kingsley’s team – Catherine Guenther – cut out segments of human DNA in the implicated region and linked each piece to a reporter gene. When these genes correctly “switch on,” they produce a distinctive blue color.

Next, Guenther introduced these pieces of switched-on DNA into mice. This allowed the team to further narrow the scope of their search until they had isolated a single piece of DNA that switched on the gene activity for developing hair follicles.

Further examining the DNA in that regulatory segment, the team found that it was just a single letter of genetic code that differed between people who have different hair colors.

The versions of this DNA associated with different hair colors were then each tested on the Kit ligand gene using cultured cells. The “blonde” switch reduced the activity of the gene by about 20%, which led the researchers to conclude they had identified a critical component of the DNA sequence.

Mice were then engineered to have a Kit ligand gene placed under either the genetic switches for blonde or brunette hair. Kingsley explains the results:

“Sure enough, when you look at them, that one base pair is enough to lighten the hair color of the animals, even though it is only a 20% difference in gene expression. This is a good example of how fine-tuned regulatory differences may be to produce different traits. The genetic mechanism that controls blonde hair doesn’t alter the biology of any other part of the body. It’s a good example of a trait that’s skin deep – and only skin deep.”

Their work with switching on different hair colors has led the team to suspect that the genome “is littered with switches.” Kingsley thinks that the various activities of Kit ligand, as well as other genes, may be adjusted by very subtle DNA tweaks.

As well as leading to a better understanding of the molecular mechanisms involved in human diversity, Kingsley hopes that this work may lead to improving human resistance to many common diseases.

“The trick is,” he says, is finding “which switches have changed to produce which traits.”

Source: Medical News Today

Medical Monday

This is a very interesting TedMed talk!


Medical Monday


Macular degeneration


Macular degeneration, often age-related macular degeneration (AMD or ARMD), is a medical condition that usually affects older adults and results in a loss of vision in the center of the visual field (the macula) because of damage to the retina. It occurs in “dry” and “wet” forms. It is a major cause of blindness and visual impairment in older adults (>50 years). Macular degeneration can make it difficult or impossible to read or recognize faces, although enough peripheral vision remains to allow other activities of daily life.

  • Race: Macular degeneration is more likely to be found in Caucasians than in people of African descent.[21][22]

Source: From Wikipedia

Medical Monday


Sedation Issues

Some people are more likely to wake up during surgical procedures than others. “Certain people are at higher risk,” says Daniel Cole, MD, a member of the American Society of Anesthesiologists. “They include those with a genetic resistance to anesthetics (red-heads, for instance, thanks to an otherwise harmless genetic mutation)….”

A multiracial person told me that she is reluctant to get deep sedation after she had the problem years ago and was told that anesthetics are given differently based on race and ethnicity. If you know anything about this, please comment or email me.-Susan

Medical Monday

Biracial toddler in need of bone marrow donor

PASADENA, Calif. (KABC) — If you have cancer and need a bone marrow transplant, finding a life-saving match can be like finding a needle in a haystack. But for one little girl, the search is even more challenging. But doctors believe you can help.

Right from birth, 21-month-old Sofia Flores knew how to shine.

“She came out with her hand up to her head…ready for the world, eyes open,” said her mom, Erica Westfall.

Westfall says Sofia hit her developmental milestones early. But she was always getting sick.

In July, a urinary tract infection prompted her parents to bring Sofia to the emergency room. There, they got surprising news.

“It was just devastating,” said Westfall.

First, doctors diagnosed her with a rare form of leukemia that only affects one percent of children.

“There were days where she was getting chemotherapy for 10 hours,” said Westfall.

Then her leukemia progressed to acute myeloid leukemia.

“Most patients in her position do not survive without a bone marrow transplant,” said transplant specialist Dr. Jerry Cheng with Kaiser Permanente Los Angeles.

Cheng says no one in Sofia’s family is a match. Her dad is Mexican and her mom is white. International registries turned up nothing.

“We try not to think about it, honestly. Day to day, we don’t really think about the odds and the numbers and percents because that makes us cry,” said Westfall.

In addition to Sofia being biracial, her dad is from Puebla, a state in Mexico. Doctors say that makes finding a match more complicated.

“The ability to find a good match, it follows along your heritage and your ethnic roots. But with the amount of diversity, especially in a great city like L.A., we do get surprises once in a while,” said Cheng.

Related Content

link: National Marrow Donor Drive locations
More: Healthy Living home page

Sofia’s parents are working with marrow matching organization A3M to organize drives. The hope is to find matches, not just for Sofia, but for many patients like her. Registering requires a saliva sample. If you match, the process is similar to donating blood. It’s a small sacrifice that can save a life.

A3M is organizing a marrow drive at Villa Parke Community Center in Pasadena on Saturday from 12 p.m. to 6 p.m.

Race-Based Medicine?

Below are a few paragraphs from a very important article about the need for race-based medicine by Henry I. Miller, a physician and fellow in Scientific Philosophy and Public Policy at Stanford University’s Hoover Institution. I urge you to follow the link to the full article at Project Syndicate. –Susan


Race-Based Medicine?

Much of the current debate centers on whether race should be a criterion for inclusion in clinical trials – and, by extension, whether drug labeling should mention race specifically. Although the issues are complicated, the solution is simple: follow the data.

Some regard race-based medical treatment as necessary to reduce health disparities, while others view it as downright discriminatory. When BiDil was approved, Francis Collins, who was Director of the US National Human Genome Research Institute at the time, warned that “we should move without delay from blurry and potentially misleading surrogates for drug response, such as race, to the more specific causes.”

Of course, Collins was correct; race is a crude and incomplete mechanism for understanding genetic differences. But we must fight illness with the data we have, not the data we wish we had. Political and ethical sensitivities notwithstanding, drug testing, approval, and labeling must go wherever the evidence leads.

To read the entire article go to:–miller

Source: Project Syndicate 

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Makensie McDaniel