Latest Mind and Matter column in the Wall Street Journal:
"You can't change human nature." The old cliché draws support from the persistence of human behavior in new circumstances. Shakespeare's plays reveal that no matter how much language, technology and mores have changed in the past 400 years, human nature is largely undisturbed. Macbeth's ambition, Hamlet's indecision, Iago's jealousy, Kate's feistiness and Juliet's love are all instantly understandable.
Recently, however, geneticists have surprised themselves by finding evidence of recent and rapid changes in human genomes in response to the pressures of civilization. For example, fair skin allows more absorption of the sun's ultraviolet rays necessary for the skin to make vitamin D. So when the northern Europeans, living in a climate with little sunshine, started to farm wheat, a food low in vitamin D, they evolved fair skin to compensate and get more of the vitamin.
So human nature may also have genetically evolved a bit in 10,000 years. People of European and Asian descent in particular have probably adapted to living more sedentary and crowded lives. But surely not very much. Eurasians' general nature differs little from those whose ancestors were still scattered hunter-gatherers just a few generations ago: many Africans, Americans and Australians.
Besides, genetic changes can't explain short-term history. A glance at world trade statistics confirms that four decades of communist rule, designed to change human nature from individualistic to communitarian, failed to extinguish the habits needed for commerce from the Chinese personality.
So if there is a human nature it is likely to be mainly universal and ancient. Ten years ago, the evolutionary psychologist Robert Kurzban did an ingenious experiment to show what can change and what can't. Generally, three features dominate an American's description of another adult: age, sex and race. Dr. Kurzban found that the tendency to categorize by race could be changed more easily than the other two.
His subjects were asked to form an impression of individuals whom they watched in conversation. They then saw a sequence of sentences and had to recall who said what. Misattribution revealed a tendency to categorize: People confused men for men and women for women, old for old and young for young, black for black and white for white.
But if the conversation showed a pattern of two coalitions with different views, then misattribution by race, but not by sex or age, ceased. "Less than four minutes of exposure to an alternate social world was enough to deflate the tendency to categorize by race." People seem to use race as a shorthand for "group," as if skin color were a different uniform, but drop it if the group cuts across races. Dr. Kurzban argued that in the ancient hunter-gatherer past, people almost never encountered other races, but frequently encountered other groups. So racial categorization is not "human nature" but culture latching on to a "groupishness" that's part of human nature.
Confirming that finding, a more recent experiment by Katherine Kinzler at the University of Chicago found that (as her paper's title says) "accent trumps race in guiding children's social preferences." Presented with photos and sometimes recordings of other children, kids chose to be friends with those of the same race if silent, but preferred those with accents like their own when they heard recordings. An unvarying human nature can still generate very different behavior. In his new book, "The Better Angels of Our Nature," Steven Pinker, trying explain the steep decline in nearly all forms of violence in recent centuries, insists that the inner demons that once drove us to violence are still there, just expressed in less destructive ways because of cultural changes that have given empathy, self-control, morality and reason the upper hand.
As Dr. Kurzban puts it, "If you let a creature develop in a world with laws that themselves have been through some interesting selection process, then that creature will be different from one in a world with different institutions."