The Invisible History of the Human Race (31 page)

Again and again science has shown through both its failures and its successes—from the grotesqueries of eugenic “science” and failed Nazi attempts to quantify race to the positive revelations of the Y chromosome—that the categorical boundaries we draw between people when we talk about race are always in part culturally determined; they never exactly fit onto real populations. There is simply no predetermined set of genetic or other physical divisions into which different human groups throughout space and time can be discretely assigned. Modern-day racists may wish to believe that some DNA is more privileged than others, but nothing in the human genome can be explained by the age-old foils of racism, such as platonic intelligence or beauty or purity.

Still, as unhelpful as the idea of race is, it is a hard one to shake off. Simply asserting that race does not exist doesn’t appear to be changing people’s minds or lives, perhaps because it seems to be so flatly contradicted by their more vivid daily encounters with different groups of people that look quite dissimilar. Insisting that race is a cultural construct doesn’t help people understand the common experience of meeting a person who appears to be, say, Chinese or northern European and finding out that she was indeed born in China or northern Europe. If race is not the thing we see in other people, then what
is
it?

The confusion arises because when we use the term “race,” we often include the idea of
ancestry
. This becomes a problem when people who want to reject race, or at least prove that it has no biological underpinning, effectively reject the idea of ancestry too. Early on critics attributed interest in the genetics of ethnicity to an unmoored “faith” in
genetics as a solution to disease. In response to a 2005
New York Times
op-ed about the
medical utility of “race,” one political scientist argued that staff and grantees of the Department of Health and Human Services and National Institutes of Health should not publish or cite anything suggesting that genetics is associated with any population category, including nationality or ethnicity, unless the finding was statistically significant
and
the description would “yield
clear benefits for public health.”

While these proposed guidelines are extreme, they exemplify a widespread anxiety that is not often so boldly articulated. Declaring statistically significant information off-limits by fiat is unscientific, and it has worrying implications for free speech. Far more important, the measure would endanger public health more than protect it. Studies of genetic correlates of disease are easily confounded by markers of ancestry. Medical research that hopes to identify genetic causes will risk being misled by false positives if it ignores the ideologically neutral markers of ancestry.

Ancestry is real and it can’t just be defined away. You can see it on people’s faces, and you can definitely identify it in their DNA. The
it
that makes letters of the genome fall into different patterns in different groups is in fact the
ancestry
of the people carrying them.

 • • • 

In 2011 Eran Elhaik was hired to solve one of the biggest jigsaw puzzles in the history of the human race; in fact, the puzzle was the history of the human race itself. Following the failed Human Genome Diversity Project, National Geographic launched the Genographic Project in 2005 to develop a way of reading people’s Y chromosome and mtDNA, and half a million people eagerly participated by contributing samples of their DNA. From the beginning, indigenous communities were approached in a different way. It was made clear that they retained ownership of their own DNA. Whereas the HGDP had proposed to keep the cell lines from samples alive in perpetuity, the new project committed to not do that, as the idea that cells would live on after their owners’ deaths was disturbing for many groups. A mouthwash was developed for sampling so that people who objected to the idea of giving blood did not have to do that. While it is hardly the case that the problems of indigenous groups have been solved, there is generally a more mutually respectful and appreciative relationship between this project and the groups it engages with.

In 2012 Genographic decided to include all the chromosomes and analyze autosomal DNA as well. Elhaik was asked to design a method that would extract the most information from a sample but at the same time extract only historical information and not anything to do with an individual’s health or features. (See chapter 14 for more about health and the genome.) Before he could do that, Elhaik had to collect a big enough set of data to survey as many different populations as possible, as he needed to see the whole in order to understand its parts. The trickiest part of the challenge was that whatever series of letters made any two populations distinct from each other was probably going to be a different set from the series that made any other two populations different.

Elhaik spent years obsessively collecting data. He collected as much as he could from publicly available data sets, and he was given data as well. “There were a lot of
data-rich scientists who were kind enough to share their data with me,” he recalled. Ultimately he was able to gather the genetic data of tens of thousands of people from almost five hundred different populations, amassing the largest set of its kind in the world.

Elhaik worked out how all the populations differed from one another by comparing each group to another one by one and working out the minimum number of letters he needed to be able to distinguish the pair. “If you have a Lebanese and a Syrian, you ask, Do I need a hundred, two hundred, a thousand, two thousand genetic markers so I can correctly classify a Lebanese as a Lebanese and a Syrian as a Syrian?”

“
You cannot do it for every population,” Elhaik clarified, “because some of them are genetically indistinguishable. I had a lot of Indian groups, including different linguistic groups and castes, but no matter how many genetic markers you are going to use, they were not separable.” Elhaik found that he needed between five hundred and two thousand letters of DNA to tell most of the subject groups apart.

Elhaik’s subject populations roughly corresponded to what we think of as different ethnic or racial groups, but it was actually ancestry that he measured. This is not a semantic trick, an attempt to replace an incendiary word (“race”) with a more neutral one (“ancestry”). Elhaik’s analysis was based on the knowledge that individuals in each group uniquely carried a particular pattern of DNA because they descended from a particular population of people. The concept of biological race is of no help here, not only because it is imprecise but also because it carries a fatally incorrect implication—the idea that people can be sorted into completely distinct genetic buckets.
Ancestry does not work that way. Elhaik now works at the University of Sheffield, and the company Prosapia Genetics has been created based on his analyses.

Since the Human Genome Project popularized the incorrect idea that two individuals from different populations are often more alike than are individuals from the same population, people have tried to remedy the misconception of genetic race by portraying the human genome as a single continuum where all groups are like beads on a string. But that’s not a useful metaphor either: You can’t take Elhaik’s hundreds of groups and place them in a single line. While the human genome can be described as a continuum, it is one that branches and changes through time. You can think of it as a tree with a definite and irreducible shape. The end of any healthy, growing branch is a population that exists today. The base of the trunk is the single population from which everyone alive today has emerged. The branches themselves may form a tangled thicket too, different twigs and branches often fusing together to form one.

If you took the genomic tree and made every part of it invisible but the ends of the branches, you would essentially have a map of current human populations. You would see that there were obvious clusters of people but also that there was continuity among the clusters. You might even be able to discern some of the world’s geography in the population map; people are often most like the people who live near them. When scientists like Elhaik analyze the DNA of living populations, they effectively make the whole ancestral tree visible. By measuring ancestry in genomes, they reveal that we are both different—different groups emerge from different branches—and the same—we all emerge from and cluster tightly around the same trunk.

Is it dangerous to contemplate the tree? Despite the resistance to genetic information about history, there has been little research into how people actually use it. Though we are by now well educated about what we fear people will feel, we don’t know much about what they actually do feel.

 • • • 

When Brian from Texas took a DNA test,
*
he had always believed that he was a mix of white, Cajun, and French Acadian. But he discovered that a significant amount of DNA on both sides of his family was usually seen in Native Americans. Although he had always identified as French, he no longer does. The results affected how he saw others too. Caucasians now looked different to him.

Brian participated in
a survey conducted by Wendy Roth, the professor from the University of British Columbia who found her great-great-great-grandfather’s name in a European cemetery. Roth was fascinated by how people’s identities were affected by information about their DNA, and she felt that there was a “
general level of ignorance, a lack of awareness, a lack of interest in this thing that should be worth studying.”

She contacted DNA test takers and found that people’s responses to news about their ancestry were often nuanced and complex and that they changed over time. Most did not experience a significant disruption in their sense of their identity, primarily because the data didn’t contain any big surprises. When people got news they weren’t expecting, for some, like Brian, it changed everything. Yet, Roth recalled, “There are very, very few people I spoke with who will completely change their identification.” Generally the people who said they were changed by news about their ancestry
expanded
their sense of self
to include the new information.

One man whose ancestry was Mexican American discovered that he had Celtic ancestry too. But he had little interest in talking about it because of the stereotype of Celts as physically large and the fact that he was small. People might think it was his fantasy. Others were quite happy to embrace the diversity and complications that their tests revealed, but they found that other members of their families were less open. One woman who considered herself black found that her genome was 39 percent European. While her response was curiosity, her sister did not embrace the news. Another woman who identified as white discovered African ancestry on her father’s side of the family, so she started going to movies and plays exploring the black experience. Yet, she told Roth, she was unable to share the news with her bigoted brother.

Some respondents embraced the new information but became hesitant at the point where it threatened to change significant aspects of their lives. A woman who found out that she had Jewish ancestry was invited to the local synagogue. But the strictness of the religion and the new and different prejudices of the people she met made her feel that she did not belong.

While some felt positive about a newly discovered multiracial history, they were reluctant to announce it in case they were viewed as “wannabes.” A number of Roth’s test takers who discovered Native American ancestry felt the news was complicated by the availability of government money to that minority. They were afraid that people would assume they had produced these lost forebears as a way to access it. Others were concerned that they would be viewed as abandoning their “real” identity and trying to pass as something else.

Sometimes the lack of participation in DNA tests was telling too: Roth was unable to find many Asians for her study and suspects that Asians are less likely to take ancestry tests. When she asked Asians who had taken the tests about this, they would tell her: “Many of us think we know what we are.” Roth observed that “such beliefs that their lineage is completely unmixed is likely no more accurate than for any other groups.” She added, “There is the sense that Asians are very homogeneous in their roots. I think it is related to the national myths and stories that people tell about who they are.”

Overall, Roth found that some people overinterpret DNA and some people don’t, and some people react extremely but most do not; in short, Roth’s responses run the usual human gamut, except for this one ray of light: When many people found out something new, their reflex was to increase their knowledge. One man who discovered that his mother’s line was connected to the Fulani tribe in Africa began to learn the language.

“This kind of testing seems to make people more aware of how much racial mixing has gone on historically,” Roth said. “I think a lot of people start out thinking of themselves as being 100 percent something, and they don’t necessarily go into genealogy because they’re trying to challenge that view, but as more people get immersed in genealogy and, especially, as they do tests like this, they realize that, no, they’re not 100 percent something. . . . There is mixing that has happened, whether it’s a long way back or whether it’s just a couple of hundred years ago or whether it is within the last generation or two.”

 • • • 

If we want to understand mixing, whether it’s in our own family or in some larger group to which we belong, we have to understand DNA, but we also have to take into account its context. Jennifer Wagner is a lawyer and anthropologist who translates science for the legal world and vice versa. She advocates studying human differences “holistically,
integrating the contributing factors of culture, sociology, history, genetics, evolutionary biology, and the like.” With a group of colleagues she is working to develop an innovative curriculum to teach about evolution using genetic genealogy (“a more exciting . . . way of teaching these concepts than is
the study of peas or fruit flies”).