We mustn't be naive about evolution

Are humans basically good — kind, generous and peaceful? Or are we essentially evil — cruel, selfish and aggressive? Evolutionary science is uncovering the answer, and it provides important guidance about how we can best live together.

But it should not be oversimplified.

In a recent column on evolution ("Could our real advantage be survival of the friendliest?" Nov. 28), Cass Sunstein discussed the human "self-domestication" theory. Summarizing a recent article by Duke anthropologist Brian Hare and a book by Hare's former teacher, Harvard's Richard Wrangham, Sunstein presents their findings that we — homo sapiens — are a domesticated version of earlier, more aggressive, human species, just as dogs are a docile version of wolves.

Like dogs, we evolved to have lower levels of "reactive aggression" toward those around us, which enabled the cooperation and communication that have propelled our species to world domination.

Sunstein's column was a feel-good piece about how we are hard-wired to get along with each other. That's great and ought to be celebrated.

The story of human domestication is much more interesting than Sunstein let on, however, and it has troublesome implications.

Hare's and Wrangham's answer to the age-old puzzle about human nature is that we have separate neurological pathways for good and evil, and they come to the fore in different contexts and for different reasons. Hitler was kind to his secretary and inconsolable at the death of his dog.

Hare shows that whether people are helpful or hurtful to others depends on how similar the others in question seem to themselves. Instinctive antagonism toward outsiders co-evolved through the same biological mechanisms that molded group solidarity. Think of parents, who are the soul of gentleness with their own children, but would readily kill to protect them.

Thus, armed conflict with neighbors — usually sneaky night raids and ambushes — is a feature of nearly every human society ever studied. And recent brain imaging studies confirm that we literally think differently about infractions committed by members of our group than about those committed by an out-group.

Wrangham's book isn't called "Human Goodness" but "The Goodness Paradox." The paradox is that domestication has a dark side — it evolved through lethal violence against bullies, nonconformists and outsiders. Once language developed, coalitions of subordinate males could plot to oust the aggressive alpha males of the kind that dominate groups of apes. And once male coalitions discovered their overwhelming power, they could employ it against all kinds of troublemakers.

Some 12,000 generations of capital punishment — that is, homicide — systematically culled from the gene pool the tendencies to domineer or deviate.

Indeed, in nomadic hunter-­gatherer societies people have been killed by male coalitions for a wide range of social transgressions — things as seemingly trivial as a woman treading on the men's secret path. The moral sense itself could be considered the instinct to look over our shoulders — we survivors of this culling process have a healthy vigilance about who might be watching. Simply putting up a picture of human eyes has been shown to deter bicycle theft and littering.

Sunstein briefly acknowledges that while domestication reduced reactive aggression, it did not affect our unique capacity for "proactive aggression." But he implies that sort of behavior consists only of "aggression that involves a lot of advance planning." In fact, it is the threat of aggression by groups of males that underlies all the coercive, hierarchical institutions of human history.

Thus, the truth is far from Sunstein's rosy picture: We evolved to be nervous conformists who get together to murder troublemakers and outsiders.

Here's the important thing. Genes don't determine behavior, they create tendencies that can be countermanded by culture and choice. Recognizing our dark tendencies, there are things we can do to curb and control them.

To start with, the self-domestication theory provides a lens through which to see more clearly our nation's important challenges.

Take immigration. We must recognize that our views on immigrants are not entirely rational but are subtly influenced by a genetically based hostility toward outsiders.

Or consider the intolerance toward unpopular speakers that is infecting college campuses. We need to be alert that our instinctive, nervous herd mentality may be operating there.

And anyone who listened to any of the congressional deliberations on impeachment has to have seen that the adversaries were literally thinking with different parts of their brains.

Be aware that nationalism is a mixed bag. It brings out our best instincts for loyalty and service, but it will always stimulate a genetic threat to international peace.

The thought experiment for how group solidarity is forged in response to an adversary is to imagine what would happen if hostile alien spaceships appeared over major cities. Those sneaky Russians and monolithic Chinese would quickly start to feel like our kin. Climate change is another kind of worldwide threat which, depending on how we address it, could forge bonds across boundaries or could lead to the mind-set of "every man for himself."

As for our nation's history of persecuting nonconformists and reformers, we need to take to heart the language of a case that new law students study, Papachristou v. City of Jacksonville.

Back in 1972, Jacksonville had a vagrancy ordinance so broad that it allowed the police to sweep up just about anyone they considered undesirable. Supreme Court Justice William Douglas, a bit of a nonconformist himself, would have none of it. He wrote that the choices to be a nightwalker or a loafer are unwritten amenities of American life that "have dignified the right of dissent and have honored the right to be nonconformists and the right to defy submissiveness. They have encouraged lives of high spirits, rather than hushed, suffocating silence."

Dare I offer the best vision for the future for a domesticated species? It would be a time when we are all citizens of the world with robust protections for individuality and nonconformity.

Evolution built us. All in the service of promoting the most base reproductive success, it engineered beings capable of great love and loyalty, works of beautiful creativity and worldwide collaboration, and awe and wonder at the mysteries of the universe. But it also endowed us with the pain of guilt and shame, anxiety about our reputations, insatiable acquisitiveness — and the potential for intolerance and cruelty.

Still, the story can be more empowering than discouraging. Knowledge is power. We are finally at the point in history where we can start to see our own evolution. And seeing it, we can refuse to be its slaves and start being its master.

Bruce Peterson is a senior district court judge who teaches a course on Lawyers as Peacemakers at the University of Minnesota Law School.