I’m fascinated by evolutionary biology — the study that examines unexpected ways we have evolved through the millennia. You may recall from high school science that natural selection favors traits that keep us alive into our reproductive years. The only thing every one of our ancestors had in common is they lived to reproduce, carrying all their genes into the next generation.

As a simple example, parents everywhere know that most children find bitter or spicy foods distasteful, although they may eventually, as adults, come to enjoy them. The theory from evolutionary biology is this: Because many poisonous plants have those qualities, a large number of children with a mutuation where they enjoy eating the hot or bitter plants that they encountered in our cave-dwelling past never made it to puberty. Those children never passed along a taste for foods that are occasionally deadly.

(In one of Michael Pollan’s early books, The Botany of Desire: A Plant’s-Eye View of the World, he flips the script, and talks about how plants co-evolved with us, protecting themselves from extinction using the same evolutinary phenomenon. He mostly talks about how plants acquired qualities appealing to us in order to thrive as crops while competing plants were forced by agrarian humans to cede soil and sun to them. It’s a fun and thought-provoking read.)

Richard Dawkins’ groundbreaking book, The Selfish Gene, took this gene-centric view of evoluton: Evolutionary pressures universally favor genetic traits that preserve a species — a genetic line — across generations.

Have We Evolved to Cooperate?

Long before the scientific method, religions attempted to explain through their stories why we are a cooperative species.

Then along came science, as a way to challenge commonly held assumptions by testing hypotheses. Galileo Galilei used astronomy to test the hypothesis, espoused by the Catholic Church, that celestial bodies including the sun circled around us. He falsified it with math, showing the earth revolved around the sun.

What if we pose the hypothesis that “Humans evolved to be as selfish as our genes,” which has often been a rationale for going to war. Is there a way to falsify this?

In other words, can we support a theory that altruism is a favorable genetic trait, using math?

That was political scientist Robert Axelrod‘s quest. Forty-one years ago, this winner of a MacArthur Genius Grant documented his research findings in The Evolution of Cooperation. It described an exercsie in early computer programming to play and win the game theory thought experiment called The Prisoner’s Dilemma.

A Test of Strategic Betrayal

Axelrod held a tournament of sorts, with dozens of his academic and scientist peers (he was teaching at the University of Michigan in Ann Arbor at the time). They were asked to write a winning algorithm for multiple Prisoner’s Dilemma game iterations.

Each strategy must specify whether to cooperate or “defect” based on the scoring rules shown in my cover photo of Professor Axelrod.

Here is the scenario of The Prisoner’s Dilemma: You and a fellow thief have been arrested and are being questioned in separate rooms. If neither of you confess and implicate the other, you both are rewarded by being released, since there is scant evidence against either of you. But if you confess and implicate the other, you are promised as the “defector” some leniency, while your accomplice gets a stiffer prison sentence. If you both defect, you each get a sentence, although not as stiff as if the defection were one-sided.

Some players in the tournament wrote an algorithm to defect every time, while others did so randomly, or following a more complicated pattern based on the opponent’s history of defection or cooperation.

Cleverly, the rules of this competion can be extrapolated as “evolutionary forces” favoring either cooperation or betrayal, over generations of conflicts between two groups. The optimal algorithm would test the hypothesis that humans have evolved to favor self-interest over cooperation.

The results of this tournament, conducted twice just to make sure the pattern would hold, were illuminating.

The best way to know if you can trust someone is to trust them — Ernest Hemingway

Of all of the strategies, the one that consistently scored the highest after many matches was as follows: Initially cooperate. After that, mirror the last play of your opponent. If they cooperated last time, do the same this time. If they defected, start the next match with a defection. Rinse and repeat.

There is a Russian proverb that was introduced to the Reagan Administration by American scholar Suzanne Massie, and used often by that president during nuclear arms negotiations: Trust but verify.

Axelrod’s 45-year-old experiment appears to contradict the belief that we as humans possess an evolved tendency toward selfishness. Instead, it appears cooperation with firm boundaries wins the day — or our entire evolutionary history.