Michael Shermer writes: It is the oldest and most universally recognized moral principle, codified more than 2,000 years ago by the Jewish sage Hillel the Elder: “Whatsoever thou wouldst that men should not do to thee, do not do that to them. This is the whole Law. The rest is only explanation.” The explanation of morality was the subject of intense theological and philosophical disputation well before Hillel, of course, and has been ever since. Lately scientists have begun weighing in with naturalistic views of the matter, and now their cause has been joined by Paul J. Zak with The Moral Molecule and Christopher Boehm with Moral Origins.

Mr. Zak, an economist and pioneer in the new science of neuroeconomics, has built his reputation on research that has identified the hormone oxytocin as a biological proxy for trust. As he documents, countries whose citizens trust one another gain economically, enjoying a higher gross domestic product, on average, than countries where lower levels of trust exist. Mr. Zak explains that trust is built through mutually beneficial exchanges that result in higher levels of oxytocin.

How does he know this? By studying blood samples taken from participants in economic-exchange games administered by researchers as well as from people in real-world encounters. “The Moral Molecule” is an engaging popular account of Mr. Zak’s decade of intense research into how oxytocin evolved for one purpose—pair bonding and attachment in social mammals—but had the bonus effect of cementing a sense of trust among strangers.

The problem to be solved here is why strangers would be nice to one another. Evolutionary “selfish gene” theory accounts for why we would be nice to our kin—they share our genes, so being altruistic and moral has an evolutionary payoff in our genes being indirectly propagated into future generations. The theory of kin selection explains how this works, and the theory of reciprocal altruism—I’ll scratch your back if you’ll scratch mine—goes a long way toward explaining why unrelated people in a social group would be kind to one another: My generosity to you today, when my fortunes are sound, may pay off down the road if life is good to you and my luck has run out. What Mr. Zak has so brilliantly done is to identify the precise biological pathways through which this behavior system evolved and operates today. [Continue reading…]