Mixed Race Studies

Large DNA Study Traces Violent History of American Slavery

The New York Times
2020-07-23

Christine Kenneally

An 1823 cross-section diagram of a ship used to carry enslaved people. incamerastock/Alamy

Scientists from the consumer genetics company 23andMe have published the largest DNA study to date of people with African ancestry in the Americas.

More than one and a half centuries after the trans-Atlantic slave trade ended, a new study shows how the brutal treatment of enslaved people has shaped the DNA of their descendants.

The report, which included more than 50,000 people, 30,000 of them with African ancestry, agrees with the historical record about where people were taken from in Africa, and where they were enslaved in the Americas. But it also found some surprises.

For example, the DNA of participants from the United States showed a significant amount of Nigerian ancestry — an unexpected finding, as the historical record does not show evidence of enslaved people taken directly to the United States from Nigeria.

At first, historians working with the researchers “couldn’t believe the amount of Nigerian ancestry in the U.S.,” said Steven Micheletti, a population geneticist at 23andMe who led the study…

…The 23andMe project found this general pattern, but also uncovered a startling difference in the experience of men and women between regions in the Americas.

The scientists calculated that enslaved women in the United States contributed 1.5 times more to the modern-day gene pool of people of African descent than enslaved men. In the Latin Caribbean, they contributed 13 times more. In Northern South America, they contributed 17 times more.

What’s more, in the United States, European men contributed three times more to the modern-day gene pool of people of African descent than European women did. In the British Caribbean, they contributed 25 times more…

Read the entire article here.

How Not To Talk About Race And Genetics

BuzzFeed
2018-03-30

Micah Baldwin / Via Flickr: micahb37

Race has long been a potent way of defining differences between human beings. But science and the categories it constructs do not operate in a political vacuum.

This open letter was produced by a group of 68 scientists and researchers. The full list of signatories can be found below.

In his newly published book Who We Are and How We Got Here, geneticist David Reich engages with the complex and often fraught intersections of genetics with our understandings of human differences — most prominently, race.

He admirably challenges misrepresentations about race and genetics made by the likes of former New York Times science writer Nicholas Wade and Nobel Laureate James Watson. As an eminent scientist, Reich clearly has experience with the genetics side of this relationship. But his skillfulness with ancient and contemporary DNA should not be confused with a mastery of the cultural, political, and biological meanings of human groups.

As a group of 68 scholars from disciplines ranging across the natural sciences, medical and population health sciences, social sciences, law, and humanities, we would like to make it clear that Reich’s understanding of “race” — most recently in a Times column warning that “it is simply no longer possible to ignore average genetic differences among ‘races’” — is seriously flawed…

Read the entire letter here.

How to Talk About ‘Race’ and Genetics

The New York Times
2018-03-30

David Reich, Professor of Genetics
Harvard Medical School
also, Investigator, Howard Hughes Medical Institute

Angie Wong

In a Sunday Review essay last weekend, David Reich, a geneticist at Harvard, argued that science is changing how we think about “race” and urged a candid discussion of the findings, whatever they may be. Hundreds of readers left comments, many expressing worry about the possibility that the results could be misinterpreted or nefariously applied. Here are Dr. Reich’s responses to some of the comments. — The Editors…

…From my point of view, it should be possible for everyone to hold in their heads the following six truths:

1. “Race” is fundamentally a social category — not a biological one — as anthropologists have shown.
2. There are clear genetic contributors to many traits, including behavior.
3. Present-day human populations, which often but not always are correlated to today’s “race” categories, have in a number of instances been largely isolated from one another for tens of thousands of years. These long separations have provided adequate opportunity for the frequencies of genetic variations to change.
4. Genetic variations are likely to affect behavior and cognition just as they affect other traits, even though we know that the average genetic influences on behavior and cognition are strongly affected by upbringing and are likely to be more modest than genetic influences on bodily traits or disease.
5. The genetic variations that influence behavior in one population will almost certainly have an effect on behavior in others populations, even if the ways those genetic variations manifest in each population may be very different. Given that all genetically determined traits differ somewhat among populations, we should expect that there will be differences in the average effects, including in traits like behavior.
6. To insist that no meaningful average differences among human populations are possible is harmful. It is perceived as misleading, even patronizing, by the general public. And it encourages people not to trust the honesty of scholars and instead to embrace theories that are not scientifically grounded and often racist…

Read the entire article here.

Who We Are and How We Got Here: Ancient DNA and the New Science of the Human Past

Pantheon
2018-03-27
368 Pages
Hardcover ISBN: 9781101870327
Ebook ISBN: 9781101870334

David Reich, Professor of Genetics
Harvard Medical School
also, Investigator, Howard Hughes Medical Institute

David Reich describes how the revolution in the ability to sequence ancient DNA has changed our understanding of the deep human past. This book tells the emerging story of our often surprising ancestry – the extraordinary ancient migrations and mixtures of populations that have made us who we are.

• A gripping account, from the head of a world-leading lab, of the picture of human history and ancestry emerging from the revolution in the study of ancient DNA.
• Describes the evidence for ancient migrations and ghosts of long-lost populations, now revealed through comparing the genomes of ancient modern humans, archaic humans, and present-day populations.
• Considers what the latest research tells us about the often surprising ancestry of the people who now inhabit Europe, Asia, Africa, and the Americas.
• Shows how there are no ‘pure’ races: all modern human populations are mixtures of more ancient ones.
• Shares new insights into how human populations spread across the world, and makes a compelling argument that ancient DNA is fundamentally changing our picture of who we are.

Here is a groundbreaking book about how the extraction of ancient DNA from ancient bones has profoundly changed our understanding of human prehistory while resolving many long-standing controversies.

Massive technological innovations now allow scientists to extract and analyze ancient DNA as never before, and it has become clear—in part from David Reich’s own contributions to the field—that genomics is as important a means of understanding the human past as archeology, linguistics, and the written word. In Who We Are and How We Got Here, Reich describes with unprecedented clarity just how the human genome provides not only all the information that a fertilized human egg needs to develop but also contains within it the history of our species. He explains how the genomic revolution and ancient DNA are transforming our understanding of the lineage of modern humans and how DNA studies reveal the deep history of inequality—among different populations, between the sexes, and among individuals within a population. His book gives the lie to the orthodoxy that there are no meaningful biological differenced among human populations, and at the same time uses the definitive evidence provided by genomics to show that the differences that do exist are unlikely to conform to familiar stereotypes.

Table Of Contents

• Acknowledgments
• Introduction
• Part I The Deep History of Our Species
  • 1 How the Genome Explains Who We Are
  • 2 Encounters with Neanderthals
  • 3 Ancient DNA Opens the Floodgates
• Part II How We Got to Where We Are Today
  • 4 Humanity’s Ghosts
  • 5 The Making of Modern Europe
  • 6 The Collision That Formed India
  • 7 In Search of Native American Ancestors
  • 8 The Genomic Origins of East Asians
  • 9 Rejoining Africa to the Human Story
• Part III The Disruptive Genome
  • 10 The Genomics of Inequality
  • 11 The Genomics of Race and Identity
  • 12 The Future of Ancient DNA
• Notes on the Illustrations
• Notes
• Index

How Genetics Is Changing Our Understanding of ‘Race’

Sunday Review
Gray Matter
The New York Times
2018-03-23

David Reich, Professor of Genetics
Harvard Medical School
also, Investigator, Howard Hughes Medical Institute

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…

Read the entire article here.

There’s No Scientific Basis for Race—It’s a Made-Up Label

National Geographic
April 2018 (The Race Issue)

By Elizabeth Kolbert
Photographs by Robin Hammond

The four letters of the genetic code —A, C, G, and T—are projected onto Ryan Lingarmillar, a Ugandan. DNA reveals what skin color obscures: We all have African ancestors.

It’s been used to define and separate people for millennia. But the concept of race is not grounded in genetics.

In the first half of the 19th century, one of America’s most prominent scientists was a doctor named Samuel Morton. Morton lived in Philadelphia, and he collected skulls.

He wasn’t choosy about his suppliers. He accepted skulls scavenged from battlefields and snatched from catacombs. One of his most famous craniums belonged to an Irishman who’d been sent as a convict to Tasmania (and ultimately hanged for killing and eating other convicts). With each skull Morton performed the same procedure: He stuffed it with pepper seeds—later he switched to lead shot—which he then decanted to ascertain the volume of the braincase.

Morton believed that people could be divided into five races and that these represented separate acts of creation. The races had distinct characters, which corresponded to their place in a divinely determined hierarchy. Morton’s “craniometry” showed, he claimed, that whites, or “Caucasians,” were the most intelligent of the races. East Asians—Morton used the term “Mongolian”—though “ingenious” and “susceptible of cultivation,” were one step down. Next came Southeast Asians, followed by Native Americans. Blacks, or “Ethiopians,” were at the bottom. In the decades before the Civil War, Morton’s ideas were quickly taken up by the defenders of slavery…

Skulls from the collection of Samuel Morton, the father of scientific racism, illustrate his classification of people into five races—which arose, he claimed, from separate acts of creation. From left to right: a black woman and a white man, both American; an indigenous man from Mexico; a Chinese woman; and a Malaysian man. Photograph by Robert Clark PHOTOGRAPHED AT PENN MUSEUM

…By analyzing the genes of present-day Africans, researchers have concluded that the Khoe-San, who now live in southern Africa, represent one of the oldest branches of the human family tree. The Pygmies of central Africa also have a very long history as a distinct group. What this means is that the deepest splits in the human family aren’t between what are usually thought of as different races—whites, say, or blacks or Asians or Native Americans. They’re between African populations such as the Khoe-San and the Pygmies, who spent tens of thousands of years separated from one another even before humans left Africa…

Read the entire article here.

Agriculture Linked to DNA Changes in Ancient Europe

The New York Times
2015-11-23

Carl Zimmer

The agricultural revolution was one of the most profound events in human history, leading to the rise of modern civilization. Now, in the first study of its kind, an international team of scientists has found that after agriculture arrived in Europe 8,500 years ago, people’s DNA underwent widespread changes, altering their height, digestion, immune system and skin color.

Researchers had found indirect clues of some of these alterations by studying the genomes of living Europeans. But the new study, they said, makes it possible to see the changes as they occurred over thousands of years.

“For decades we’ve been trying to figure out what happened in the past,” said Rasmus Nielsen, a geneticist at the University of California, Berkeley, who was not involved in the new study. “And now we have a time machine.”

…Dr. Reich and his colleagues also tracked changes in the color of European skin.

The original hunter-gatherers, descendants of people who had come from Africa, had dark skin as recently as 9,000 years ago. Farmers arriving from Anatolia were lighter, and this trait spread through Europe. Later, a new gene variant emerged that lightened European skin even more.

Why? Scientists have long thought that light skin helped capture more vitamin D in sunlight at high latitudes. But early hunter-gatherers managed well with dark skin. Dr. Reich suggests that they got enough vitamin D in the meat they caught.

He hypothesizes that it was the shift to agriculture, which reduced the intake of vitamin D, that may have triggered a change in skin color…

Read the entire article here.

How Europeans evolved white skin

Science
2015-04-02
DOI: 10.1126/science.aab2435

Ann Gibbons, Contributing Correspondent

ST. LOUIS, MISSOURI—Most of us think of Europe as the ancestral home of white people. But a new study shows that pale skin, as well as other traits such as tallness and the ability to digest milk as adults, arrived in most of the continent relatively recently. The work, presented here last week at the 84th annual meeting of the American Association of Physical Anthropologists, offers dramatic evidence of recent evolution in Europe and shows that most modern Europeans don’t look much like those of 8000 years ago.

The origins of Europeans have come into sharp focus in the past year as researchers have sequenced the genomes of ancient populations, rather than only a few individuals. By comparing key parts of the DNA across the genomes of 83 ancient individuals from archaeological sites throughout Europe, the international team of researchers reported earlier this year that Europeans today are a mix of the blending of at least three ancient populations of hunter-gatherers and farmers who moved into Europe in separate migrations over the past 8000 years. The study revealed that a massive migration of Yamnaya herders from the steppes north of the Black Sea may have brought Indo-European languages to Europe about 4500 years ago.

Now, a new study from the same team drills down further into that remarkable data to search for genes that were under strong natural selection—including traits so favorable that they spread rapidly throughout Europe in the past 8000 years. By comparing the ancient European genomes with those of recent ones from the 1000 Genomes Project, population geneticist Iain Mathieson, a postdoc in the Harvard University lab of population geneticist David Reich, found five genes associated with changes in diet and skin pigmentation that underwent strong natural selection…

Read the entire article here.

White? Black? A Murky Distinction Grows Still Murkier

The New York Times
2014-12-24

Carl Zimmer

In 1924, the State of Virginia attempted to define what it means to be white.

The state’s Racial Integrity Act, which barred marriages between whites and people of other races, defined whites as people “whose blood is entirely white, having no known, demonstrable or ascertainable admixture of the blood of another race.”

There was just one problem. As originally written, the law would have classified many of Virginia’s most prominent families as not white, because they claimed to be descended from Pocahontas.

So the Virginia legislature revised the act, establishing what came to be known as the “Pocahontas exception.” Virginians could be up to one-sixteenth Native American and still be white in the eyes of the law.

People who were one-sixteenth black, on the other hand, were still black.

In the United States, there is a long tradition of trying to draw sharp lines between ethnic groups, but our ancestry is a fluid and complex matter. In recent years geneticists have been uncovering new evidence about our shared heritage, and last week a team of scientists published the biggest genetic profile of the United States to date, based on a study of 160,000 people…

Read the entire article here.

The Genetic Ancestry of African Americans, Latinos, and European Americans across the United States

The American Journal of Human Genetics
Volume 96, Issue 1, 2015-01-08
Pages 37–53
DOI: 10.1016/j.ajhg.2014.11.010

Katarzyna Bryc, Research Fellow in Genetics (EXT)
Department of Genetics
Harvard Medical School, Boston, Massachusetts

Eric Y. Durand
23andMe, Inc., Mountain View, California

J. Michael Macpherson, Assistant Professor
School of Computational Sciences
Chapman University, Orange, California

David Reich, Professor of Genetics
Harvard Medical School, Boston, Massachusetts

Joanna L. Mountain, Senior Director of Research
23andMe, Inc., Mountain View, California

Over the past 500 years, North America has been the site of ongoing mixing of Native Americans, European settlers, and Africans (brought largely by the trans-Atlantic slave trade), shaping the early history of what became the United States. We studied the genetic ancestry of 5,269 self-described African Americans, 8,663 Latinos, and 148,789 European Americans who are 23andMe customers and show that the legacy of these historical interactions is visible in the genetic ancestry of present-day Americans. We document pervasive mixed ancestry and asymmetrical male and female ancestry contributions in all groups studied. We show that regional ancestry differences reflect historical events, such as early Spanish colonization, waves of immigration from many regions of Europe, and forced relocation of Native Americans within the US. This study sheds light on the fine-scale differences in ancestry within and across the United States and informs our understanding of the relationship between racial and ethnic identities and genetic ancestry.

Read the entire article here.