Nicholas Wade, TIME, May 9, 2014
A longstanding orthodoxy among social scientists holds that human races are a social construct and have no biological basis. A related assumption is that human evolution halted in the distant past, so long ago that evolutionary explanations need never be considered by historians or economists.
In the decade since the decoding of the human genome, a growing wealth of data has made clear that these two positions, never at all likely to begin with, are simply incorrect. There is indeed a biological basis for race. And it is now beyond doubt that human evolution is a continuous process that has proceeded vigorously within the last 30,000 years and almost certainly–though very recent evolution is hard to measure–throughout the historical period and up until the present day.
New analyses of the human genome have established 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.
Analysis of genomes from around the world establishes that there is a biological basis for race, despite the official statements to the contrary of leading social science organizations. 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.
Racism and discrimination are wrong as a matter of principle, not of science. That said, it is hard to see anything in the new understanding of race that gives ammunition to racists. The reverse is the case. Exploration of the genome has shown that all humans, whatever their race, share the same set of genes. Each gene exists in a variety of alternative forms known as alleles, so one might suppose that races have distinguishing alleles, but even this is not the case. A few alleles have highly skewed distributions but these do not suffice to explain the difference between races. The difference between races seems to rest on the subtle matter of relative allele frequencies. The overwhelming verdict of the genome is to declare the basic unity of humankind.
Genetics and Social Behavior
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, 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. 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. Though the role of these selected brain genes is not yet understood, the obvious truth is that genes affecting the brain are just as much subject to natural selection as any other category of gene.
What might be the role of these brain genes favored by natural selection? Edward O. Wilson was pilloried for saying in his 1975 book Sociobiology that humans have many social instincts. But subsequent research has confirmed the idea that we are inherently sociable. From our earliest years we want to belong to a group, conform to its rules and punish those who violate them. Later, our instincts prompt us to make moral judgments and to defend our group, even at the sacrifice of one’s own life.
Anything that has a genetic basis, such as these social instincts, can be varied by natural selection. The power of modifying social instincts is most visible in the case of ants, the organisms that, along with humans, occupy the two pinnacles of social behavior. Sociality is rare in nature because to make a society work individuals must moderate their powerful selfish instincts and become at least partly altruistic. But once a social species has come into being, it can rapidly exploit and occupy new niches just by making minor adjustments in social behavior. Thus both ants and humans have conquered the world, though fortunately at different scales.
The Four Key Traits
[Gregory] Clark has documented four behaviors that steadily changed in the English population between 1200 and 1800, as well as a highly plausible mechanism of change. The four behaviors are those of interpersonal violence, literacy, the propensity to save, and the propensity to work.
These behavioral changes in the English population between 1200 and 1800 were of pivotal economic importance. They gradually transformed a violent and undisciplined peasant population into an efficient and productive workforce. Turning up punctually for work every day and enduring eight eight hours or more of repetitive labor is far from being a natural human behavior. Hunter-gatherers do not willingly embrace such occupations, but agrarian societies from their beginning demanded the discipline to labor in the fields and to plant and harvest at the correct times. Disciplined behaviors were probably evolving gradually within the agrarian English population for many centuries before 1200, the point at which they can be documented.
Clark has uncovered a genetic mechanism through which the Malthusian economy may have wrought these changes on the English population: The rich had more surviving children than did the poor. From a study of wills made between 1585 and 1638, he finds that will makers with £9 or less to leave their heirs had, on average, just under two children. The number of heirs rose steadily with assets, such that men with more than £1,000 in their gift, who formed the wealthiest asset class, left just over four children.
The English population was fairly stable in size from 1200 to 1760, meaning that if the rich were having more children than the poor, most children of the rich had to sink in the social scale, given that there were too many of them to remain in the upper class.
Their social descent had the far-reaching genetic consequence that they carried with them inheritance for the same behaviors that had made their parents rich. The values of the upper middle class–nonviolence, literacy, thrift, and patience–were thus infused into lower economic classes and throughout society. Generation after generation, they gradually became the values of the society as a whole. This explains the steady decrease in violence and increase in literacy that Clark has documented for the English population. Moreover, the behaviors emerged gradually over several centuries, a time course more typical of an evolutionary change than a cultural change.
Economic historians tend to see the Industrial Revolution as a relatively sudden event and their task as being to uncover the historical conditions that precipitated this immense transformation of economic life. But profound events are likely to have profound causes. The Industrial Revolution was caused not by events of the previous century but by changes in human economic behavior that had been slowly evolving in agrarian societies for the previous 10,000 years.
This of course explains why the practices of the Industrial Revolution were adopted so easily by other European countries, the United States, and East Asia, all of whose populations had been living in agrarian economies and evolving for thousands of years under the same harsh constraints of the Malthusian regime. No single resource or institutional change–the usual suspects in most theories of the Industrial Revolution–is likely to have become effective in all these countries around 1760, and indeed none did.
That leaves the questions of why the Industrial Revolution was perceived as sudden and why it emerged first in England instead of in any of the many other countries where conditions were ripe. Clark’s answer to both these questions lies in the sudden growth spurt in the English population, which tripled between 1770 and 1860. It was this alarming expansion that led Malthus to write his foreboding essay on population.
But contrary to Malthus’s gloomy prediction of a population crash induced by vice and famine, which would have been true at any earlier stage of history, incomes on this occasion rose, heralding the first escape of an economy from the Malthusian trap. English workmen contributed to this spurt, Clark dryly notes, as much by their labors in the bedroom as on the factory floor.
Clark’s data provide substantial evidence that the English population responded genetically to the harsh stresses of a Malthusian regime and that the shifts in its social behavior from 1200 to 1800 were shaped by natural selection. The burden of proof is surely shifted to those who might wish to assert that the English population was miraculously exempt from the very forces of natural selection whose existence it had suggested to Darwin.
Explaining Ashkenazi IQ
A second instance of very recent human evolution may well be in evidence in European Jews, particularly the Ashkenazim of northern and central Europe. In proportion to their population, Jews have made outsize contributions to Western civilization. A simple metric is that of Nobel prizes: Though Jews constitute only 0.2% of the world’s population, they won 14% of Nobel prizes in the first half of the 20th century, 29% in the second and so far 32% in the present century. There is something here that requires explanation. If Jewish success were purely cultural, such as hectoring mothers or a zeal for education, others should have been able to do as well by copying such cultural practices. It’s therefore reasonable to ask if genetic pressures in Jews’ special history may have enhanced their cognitive skills.
Just such a pressure is described by two economic historians, Maristella Botticini and Zvi Eckstein, in their book “The Chosen Few.” In 63 or 65 AD, the high priest Joshua ben Gamla decreed that every Jewish father should send his sons to school so that they could read and understand Jewish law. Jews at that time earned their living mostly by farming, as did everyone else, and education was both expensive and of little practical use. Many Jews abandoned Judaism for the new and less rigorous Jewish sect now known as Christianity.
Botticini and Eckstein say nothing about genetics but evidently, if generation after generation the Jews less able to acquire literacy became Christians, literacy and related abilities would on average be enhanced among those who remained Jews.
As commerce started to pick up in medieval Europe, Jews as a community turned out to be ideally suited for the role of becoming Europe’s traders and money-lenders. In a world where most people were illiterate, Jews could read contracts, keep accounts, appraise collateral, and do business arithmetic. They formed a natural trading network through their co-religionists in other cities, and they had rabbinical courts to settle disputes. Jews moved into money-lending not because they were forced to do so, as some accounts suggest, but because they chose the profession, Botticini and Eckstein say. It was risky but highly profitable. The more able Jews thrived and, just as in the rest of the pre-19th century world, the richer were able to support more surviving children.
As Jews adapted to a cognitively demanding niche, their abilities increased to the point that the average IQ of Ashkenazi Jews is, at 110 to 115, the highest of any known ethnic group. The population geneticists Henry Harpending and Gregory Cochran have calculated that, assuming a high heritability of intelligence, Ashkenazi IQ could have risen by 15 points in just 500 years. Ashkenazi Jews first appear in Europe around 900 AD, and Jewish cognitive skills may have been increasing well before then.
The emergence of high cognitive ability among the Ashkenazim, if genetically based, is of interest both in itself and as an instance of natural selection shaping a population within the very recent past.
The Adaptive Response to Different Societies
The hand of evolution seems visible in the major transitions in human social structure and in the two case studies described above. This is of course a hypothesis; proof awaits detection of the genes in question. If significant evolutionary changes can occur so recently in history, other major historical events may have evolutionary components. One candidate is the rise of the West, which was prompted by a remarkable expansion of European societies, both in knowledge and geographical sway, while the two other major powers of the medieval world, China and the house of Islam, ascendant until around 1500 AD, were rapidly overtaken.
In his book The Wealth and Poverty of Nations, the economic historian David Landes examines every possible factor for explaining the rise of the West and the stagnation of China and concludes, in essence, that the answer lies in the nature of the people. Landes attributes the decisive factor to culture, but describes culture in such a way as to imply race.
“If we learn anything from the history of economic development, it is that culture makes all the difference,” he writes. “Witness the enterprise of expatriate minorities–the Chinese in East and Southeast Asia, Indians in East Africa, Lebanese in West Africa, Jews and Calvinists throughout much of Europe, and on and on. Yet culture, in the sense of the inner values and attitudes that guide a population, frightens scholars. It has a sulfuric odor of race and inheritance, an air of immutability.”
Sulfuric odor or not, the culture of each race is what Landes suggests has made the difference in economic development. The data gathered by Clark on declining rates of violence and increasing rates of literacy from 1200 to 1800 provide some evidence for a genetic component to culture and social institutions.
The rise of the West, too, is unlikely to have been just some cultural accident. As European populations became adapted to the geographic and military conditions of their particular ecological habitat, they produced societies that have turned out to be more innovative and productive than others, at least under present circumstances.
That does not of course mean that Europeans are superior to others–a meaningless term in any case from the evolutionary perspective–any more than Chinese were superior to others during their heyday. China’s more authoritarian society may once again prove more successful, particularly in the wake of some severe environmental stress.
Civilizations may rise and fall but evolution never ceases, which is why genetics may play some role alongside the mighty force of culture in shaping the nature of human societies. History and evolution are not separate processes, with human evolution grinding to a halt some decent interval before history begins. The more that we are able to peer into the human genome, the more it seems that the two processes are delicately intertwined.