Where does morality come from? (And by "morality" I mean the impulse that prevents us from beating or killing one another, and not those other issues that are often lumped under the category of "family values.")
To children, morality might seem like a set of arbitrary rules imposed by authority figures. More thoughtful people might consider morality a kind of "social contract" — standards of conduct we've all agreed upon to make life a little easier to live. Regardless, our need to explicitly elucidate these rules makes them seem counter to human nature. Without these standards, it seems, we'd soon degenerate into our primitive ways and start knocking each other over the heads with sticks and rocks.
Thomas Hobbes, for example, thought that mankind started out its existence as disparate solitary and hostile beings, and only later reluctantly grouped together into tribes and nations. In the post-1859 era, Thomas H. Huxley — who was the nineteenth century's major defender of Darwin's theory of evolution by natural selection — recognized a continuity between animals and man except in the area of morality, which he thought came entirely from man's superior intellect rejecting its own animal nature.
T. H. Huxley's concept is what famed primate scientist Frans de Waal calls the "veneer theory" of morality, which is the idea that morality is something we've deliberately pasted on to our otherwise gross human nature in order to facilitate social interaction. In his fascinating and thought-provoking book entitled Primates and Philosophers: How Morality Evolved (Princeton University Press, 2006) Frans de Waal has attempted to discredit veneer theory and argue that moral impulses are instead intrinsic and even instinctual.
De Waal believes that we are intrinsically moral beings because we have inherited crucial building blocks of morality from our primate ancestors, and particularly our closest relations, chimps and bonobos. He has spent decades studying primate social structures, and has written extensively on his findings, beginning with the book Chimpanzee Politics (1982). Even very basic observations makes Hobbes' concept that we started out as solitary individuals seems absurd: Our closest primate ancestors are very social beings, and as best we know, humans also have always been social beings. "A good illustration of the thoroughly social nature of our species is that, second to the death penalty, solitary confinement is the most extreme punishment we can think of." (p. 5)
Drawing on a combination of experimentation and observation, de Waal detects in our primate ancestors certain key components of morality, such as empathy, consolation, reciprocity, and concepts of fairness. To be sure, the moral behavior of the great apes doesn't ever seem quite as sophisticated or textured as human responses, but it is de Waal's contention that morality can be analyzed in levels. Evolution has provided the basics of morality by favoring certain behaviors that facilitate social interaction, so it might very well be that evolution has prompted the additional levels as well.
De Waal's essay is based on the Tanner Lectures he delivered at Princeton University's Center for Human Values in 2004, and with a few appendices only totals 80 pages in length. The remainder of the book consists of four "comments" to de Waal's ideas by philosophers Robert Wright, Christine M. Korsgaard, Philip Kitcher, and Peter Singer. These are certainly not "filler" and are often as interesting as de Waal's original essay. The book concludes with a "response to the commentators" by de Waal, making this book a great rounded give-and-take introduction to the whole concept of evolutionary morality.
To me, one of the most interesting parts of the book is Peter Singer's discussion of experiments performed by Joshua Greene involving brain imagery of people presented with classical "runaway trolley" problems. (p. 146-150) In one problem, a switch can be thrown to divert a runaway trolley so it only kills one person rather than four. In another, you have to push a big person off a bridge to divert the trolley. With both problems, people's responses clearly involve areas of the brain devoted to emotions. Their reactions — yes to throwing the switch, no to pushing the person off the bridge — are too fast for reasoned consideration. But with the second problem, some people eventually get the rational part of their brain working and decide that pushing the person off the bridge is the proper response. That's reasoned human morality overriding inherited primate morality.
In light of these ideas, the moral philosopher who comes across as most prescient is David Hume, who together with his fellow Scots, Francis Hutcheson and Adam Smith, developed the so-called sentimentalist theory of morality. Morality is not the product of reasoning, they argued, but instead an emotional response. Interestingly, Charles Darwin was well read in these writers of the Scottish Enlightenment, and he too tended to see morality as an emotional response that is the outgrowth of an evolutionary process. (p. 15-17) This "alliance between Darwin and Hume" (as Philip Kitcher calls it, p. 124) now seems a good foundation for understanding ourselves and these odd brains we've inherited.