A Troublesome Inheritance: Genes, Race and Human History - Softcover

Wade, Nicholas

Softcover

ISBN 10: 0143127160 ISBN 13: 9780143127161

Publisher: Penguin Books, 2015

Synopsis

Drawing on startling new evidence from the mapping of the genome, an explosive new account of the genetic basis of race and its role in the human story
 

Fewer ideas have been more toxic or harmful than the idea of the biological reality of race, and with it the idea that humans of different races are biologically different from one another. For this understandable reason, the idea has been banished from polite academic conversation. Arguing that race is more than just a social construct can get a scholar run out of town, or at least off campus, on a rail. Human evolution, the consensus view insists, ended in prehistory.

Inconveniently, as Nicholas Wade argues in A Troublesome Inheritance, the consensus view cannot be right. And in fact, we know that populations have changed in the past few thousand years—to be lactose tolerant, for example, and to survive at high altitudes. Race is not a bright-line distinction; by definition it means that the more human populations are kept apart, the more they evolve their own distinct traits under the selective pressure known as Darwinian evolution. For many thousands of years, most human populations stayed where they were and grew distinct, not just in outward appearance but in deeper senses as well.

Wade, the longtime journalist covering genetic advances for The New York Times, draws widely on the work of scientists who have made crucial breakthroughs in establishing the reality of recent human evolution. The most provocative claims in this book involve the genetic basis of human social habits. What we might call middle-class social traits—thrift, docility, nonviolence—have been slowly but surely inculcated genetically within agrarian societies, Wade argues. These “values” obviously had a strong cultural component, but Wade points to evidence that agrarian societies evolved away from hunter-gatherer societies in some crucial respects. Also controversial are his findings regarding the genetic basis of traits we associate with intelligence, such as literacy and numeracy, in certain ethnic populations, including the Chinese and Ashkenazi Jews.

Wade believes deeply in the fundamental equality of all human peoples. He also believes that science is best served by pursuing the truth without fear, and if his mission to arrive at a coherent summa of what the new genetic science does and does not tell us about race and human history leads straight into a minefield, then so be it. This will not be the last word on the subject, but it will begin a powerful and overdue conversation.

About this title

About the Author:

Nicholas Wade received a BA in natural sciences from King’s College, Cambridge. He was the deputy editor of Nature magazine in London and then became that journal’s Washington correspondent. He joined Science magazine in Washington as a reporter and later moved to The New York Times, where he has been an editorial writer, concentrating on issues of defense, space, science, medicine, technology, genetics, molecular biology, the environment, and public policy, a science reporter, and a science editor.

Excerpt. © Reprinted by permission. All rights reserved.:

1

Evolution, Race and History

Since the decoding of the human genome in 2003, a sharp new light has been shed on human evolution, raising many interesting but awkward questions.

It is now beyond doubt that human evolution is a continuous process that has proceeded vigorously within the past 30,000 years and almost certainly—though very recent evolution is hard to measure—throughout the historical period and up until the present day. It would be of the greatest interest to know how people have evolved in recent times and to reconstruct the fingerprints of natural selection as it molded and reworked the genetic clay. Any degree of evolution in social behavior found to have taken place during historical times could help explain significant features of today’s world.

But the exploration and discussion of these issues is complicated by the fact of race. Ever since the first modern humans dispersed from the ancestral homeland in northeast Africa some 50,000 years ago, the populations on each continent have evolved largely independently of one another as each adapted to its own regional environment. Under these various local pressures, there developed the major races of humankind, those of Africans, East Asians and Europeans, as well as many smaller groups.

Because of these divisions in the human population, anyone interested in recent human evolution is almost inevitably studying human races, whether they wish to or not. Scientific inquiry thus runs into potential conflict with the public policy interest of not generating possibly invidious comparisons that might foment racism. Several of the intellectual barriers erected many years ago to combat racism now stand in the way of studying the recent evolutionary past. These include the assumption that there has been no recent human evolution and the assertion that races do not exist.

The New View of Human Evolution

New analyses of the human genome establish that human evolution has been recent, copious and regional. Biologists scanning the genome for evidence of natural selection have detected signals of many genes that have been favored by natural selection in the recent evolutionary past. No less than 14% of the human genome, according to one estimate, has changed under this recent evolutionary pressure. Most of these signals of natural selection date from 30,000 to 5,000 years ago, just an eyeblink in evolution’s 3 billion year timescale.

Natural selection has continued to mold the human genome, doubtless up until the present day, although the signals of evolution within the past few hundred or thousand years are harder to pick up unless the force of selection has been extremely strong. One of the most recent known dates at which a human gene has been changed by evolution is from 3,000 years ago, when Tibetans evolved a genetic variant that lets them live at high altitude.

Several instances have now come to light of natural selection shaping human traits within just the past few hundred years. Under the pressure of selection, for example, the age of first reproduction among women born between 1799 and 1940 on L’Isle-aux-Coudres, an island in the Saint Lawrence River near Quebec, fell from 26 to 22 years, according to researchers who were able to study an unusually complete record of marriages, births and deaths in the island’s parish records.

The researchers argue that other possible effects, like better nutrition, can be ruled out as explanations, and note that the tendency to give birth at a younger age appeared to be heritable, confirming that a genetic change had taken place. “Our study supports the idea that humans are still evolving,” they write. “It also demonstrates that microevolution is detectable over just a few generations in a long-lived species.”

Another source of evidence for very recent human evolution is that of the multigenerational surveys conducted for medical reasons, like the Framingham Heart Study. Borrowing statistical methods developed by evolutionary biologists for measuring natural selection, physicians have recently been able to tease out certain bodily changes that are under evolutionary pressure in these large patient populations. The traits include age at first reproduction, which is decreasing in modern societies, and age at menopause, which is increasing. The traits are of no particular importance in themselves and have been measured just because the relevant data were collected by the physicians who designed the studies. But the statistics suggest that the traits are inherited, and if so, they are evidence of evolution at work in present-day populations. “The evidence strongly suggests that we are evolving and that our nature is dynamic, not static,” a Yale biologist, Stephen Stearns, concludes in summarizing 14 recent studies that measured evolutionary change in living populations.

Human evolution has not only been recent and extensive; it has also been regional. The period of 30,000 to 5,000 years ago, from which signals of recent natural selection can be detected, occurred after the splitting of the three major races, and so represents selection that has occurred largely independently within each race. The three principal races are Africans (those who live south of the Sahara), East Asians (Chinese, Japanese and Koreans) and Caucasians (Europeans and the peoples of the Near East and the Indian subcontinent). In each of these races, a different set of genes has been changed by natural selection, as is described further in chapter 5. This is just what would be expected for populations that had to adapt to different challenges on each continent. The genes specially affected by natural selection control not only expected traits like skin color and nutritional metabolism but also some aspects of brain function, although in ways that are not yet understood.

Analysis of genomes from around the world establishes that there is indeed a biological reality to race, despite the official statements to the contrary of leading social science organizations. A longer discussion of this issue is offered in chapter 5, but an illustration of the point is the fact that with mixed-race populations, such as African Americans, geneticists can now track along an individual’s genome and assign each segment to an African or European ancestor, an exercise that would be impossible if race did not have some basis in biological reality.

The fact that human evolution has been recent, copious and regional is not widely recognized, even though it has now been reported by many articles in the literature of genetics. The reason is in part that the knowledge is so new and in part because it raises awkward challenges to deeply held conventional wisdom.

The Social Science Creed and Evolution

It has long been convenient for social scientists to assume that human evolution ground to a halt in the distant past, perhaps when people first learned to put a roof over their heads and to protect themselves from the hostile forces of nature. Evolutionary psychologists teach that the human mind is adapted to the conditions that prevailed at the end of the last age, some 10,000 years ago. Historians, economists, anthropologists and sociologists assume there has been no change in innate human behavior during the historical period.

This belief in the recent suspension of evolution, at least for people, is shared by the major associations of social scientists, which assert that race does not even exist, at least in the biological sense. “Race is a recent human invention,” proclaims the American Anthropological Association. “Race is about culture, not biology.” A recent book published by the association states that “Race is not real in the way we think of it: as deep, primordial, and biological. Rather it is a foundational idea with devastating consequences because we, through our history and culture, made it so.”

The commonsense conclusion—that race is both a biological reality and a politically fraught idea with sometimes pernicious consequences—has also eluded the American Sociological Association. The group states that “race is a social construct” and warns “of the danger of contributing to the popular conception of race as biological.”

The social scientists’ official view of race is designed to support the political view that genetics cannot possibly be the reason why human societies differ—the answer must lie exclusively in differing human cultures and the environment that produced them. The social anthropologist Franz Boas established the doctrine that human behavior is shaped only by culture and that no culture is superior to any other. From this point of view it follows that all humans are essentially interchangeable apart from their cultures, and that more complex societies owe their greater strength or prosperity solely to fortunate accidents such as that of geography.

The recent discoveries that human evolution has been recent, copious and regional severely undercut the social scientists’ official view of the world because they establish that genetics may have played a possibly substantial role alongside culture in shaping the differences between human populations. Why then do many researchers still cling to the notion that culture alone is the only possible explanation for the differences between human societies?

One reason is, of course, the understandable fear that exploration of racial differences will give support to racism, a question addressed below. Another is the inherent inertia of the academic world. University researchers do not act independently but rather as communities of scholars who constantly check and approve one another’s work. This is especially so in science, where grant applications must be approved by a panel of peers, and publications submitted to the scrutiny of editors and reviewers. The high advantage of this process is that the statements

scholars make in public are usually a lot more than their own opinion—they are the certified knowledge of a community of experts.

But a drawback of the system is its occasional drift toward extreme conservatism. Researchers get attached to the view of their field they grew up with and, as they grow older, they may gain the influence to thwart change. For 50 years after it was first proposed, leading geophysicists strenuously resisted the idea that the continents have drifted across the face of the globe. “Knowledge advances, funeral by funeral,” the economist Paul Samuelson once observed.

Another kind of flaw occurs when universities allow a whole field of scholars to drift politically to the left or to the right. Either direction is equally injurious to the truth, but at present most university departments lean strongly to the left. Any researcher who even discusses issues politically offensive to the left runs the risk of antagonizing the professional colleagues who must approve his requests for government funds and review his articles for publication. Self-censorship is the frequent response, especially in anything to do with the recent differential evolution of the human population. It takes only a few vigilantes to cow the whole campus. The result is that researchers at present routinely ignore the biology of race, or tiptoe around the subject, lest they be accused of racism by their academic rivals and see their careers destroyed.

Resistance to the idea that human evolution is recent, copious and regional is unlikely to vanish unless scholars can be persuaded that exploration of the recent evolutionary past will not lead to a resurgence of racism. In fact, such a resurgence seems most unlikely, for the following reasons.

Genomics and Racial Differences

In the first place, opposition to racism is now well entrenched, at least in the Western world. It is hard to conceive of any circumstance that would reverse or weaken this judgment, particularly any scientific evidence. Racism and discrimination are wrong as a matter of principle, not of science. Science is about what is, not what ought to be. Its shifting sands do not support values, so it is foolish to place them there.

Academics, who are obsessed with intelligence, fear the discovery of a gene that will prove one major race is more intelligent than another. But that is unlikely to happen anytime soon. Although intelligence has a genetic basis, no genetic variants that enhance intelligence have yet been found. The reason, almost certainly, is that there are a great many such genes, each of which has too small an effect to be detectable with present methods. If researchers should one day find a gene that enhances intelligence in East Asians, say, they can hardly argue on that basis that East Asians are more intelligent than other races, because hundreds of similar genes remain to be discovered in Europeans and Africans.

Even if all the intelligence-enhancing variants in each race had been identified, no one would try to compute intelligence on the basis of genetic information: it would be far easier just to apply an intelligence test. But IQ tests already exist, for what they may be worth.

Even if it were proved that one race were genetically more intelligent than another, what consequence would follow? In fact, not much of one. East Asians score around 105 on intelligence tests, an average above that of Europeans, whose score is 100. A higher IQ score doesn’t make East Asians morally superior to other races. East Asian societies have many virtues but are not necessarily more successful than European societies in meeting their members’ needs.

The notion that any race has the right to dominate others or is superior in any absolute sense can be firmly rejected as a matter of principle and, being rooted in principle, is unassailable by science. Nonetheless, races being different, it is inevitable that science will establish relative advantages in some traits. Because of genetic variants, Tibetans and Andean highlanders are better than others at living at high altitudes. At every Olympic games since 1980, every finalist in the men’s 100-meter race has had West African ancestry. 9 It would be no surprise if some genetic factor were found to contribute to such athleticism.

Study of the genetics of race will inevitably reveal differences, some of which will show, for those who may be interested, that one race has some slight edge over another in a specified trait. But this kind of inquiry will also establish a wider and more important truth, that all differences between races are variations on a common theme.

To discover that genetics plays some role in the differences between the major human societies does not mean that that role is dominant. Genes do not determine human behavior; they merely predispose people to act in certain ways. Genes explain a lot, probably far more than is at present understood or acknowledged. But their influence in most situations is or can be overwhelmed by learned behavior, or culture. To say that genes explain everything about human social behavior would be as absurd as to assume that they explain nothing.

Social scientists often write as if they believe that culture explains everything and race nothing, and that all cultures are of equal value. The emerging truth is more complicated. Human nature is very similar throughout the world. But though people are much the same, their societies differ greatly in their structure, their institutions and their achievements. Contrary to the central belief of multiculturalists, Western culture has achieved far more than other cultures in many significant spheres and has done so because Europeans, probably for reasons of both evolution and history, have been able to create open and innovative societies, starkly different from the defau...

About this edition

• Publisher: Penguin Books
• Publication date: 2015
• ISBN 10: 0143127160
• ISBN 13: 9780143127161
• Binding: Paperback
• Number of pages: 288