At the same time, though, people everywhere have some sense of right and wrong. You won’t find a society where people don’t have some notion of fairness, don’t put some value on loyalty and kindness, don’t distinguish between acts of cruelty and innocent mistakes, don’t categorize people as nasty or nice. These universals make evolutionary sense. Since natural selection works, at least in part, at a genetic level, there is a logic to being instinctively kind to our kin, whose survival and well-being promote the spread of our genes. More than that, it is often beneficial for humans to work together with other humans, which means that it would have been adaptive to evaluate the niceness and nastiness of other individuals. All this is reason to consider the innateness of at least basic moral concepts.

In addition, scientists know that certain compassionate feelings and impulses emerge early and apparently universally in human development. These are not moral concepts, exactly, but they seem closely related. One example is feeling pain at the pain of others. In his book “The Expression of the Emotions in Man and Animals,” Charles Darwin, a keen observer of human nature, tells the story of how his first son, William, was fooled by his nurse into expressing sympathy at a very young age: “When a few days over 6 months old, his nurse pretended to cry, and I saw that his face instantly assumed a melancholy expression, with the corners of his mouth strongly depressed.”

There seems to be something evolutionarily ancient to this empathetic response. If you want to cause a rat distress, you can expose it to the screams of other rats. Human babies, notably, cry more to the cries of other babies than to tape recordings of their own crying, suggesting that they are responding to their awareness of someone else’s pain, not merely to a certain pitch of sound. Babies also seem to want to assuage the pain of others: once they have enough physical competence (starting at about 1 year old), they soothe others in distress by stroking and touching or by handing over a bottle or toy. There are individual differences, to be sure, in the intensity of response: some babies are great soothers; others don’t care as much. But the basic impulse seems common to all. (Some other primates behave similarly: the primatologist Frans de Waal reports that chimpanzees “will approach a victim of attack, put an arm around her and gently pat her back or groom her.” Monkeys, on the other hand, tend to shun victims of aggression.)

Some recent studies have explored the existence of behavior in toddlers that is “altruistic” in an even stronger sense — like when they give up their time and energy to help a stranger accomplish a difficult task. The psychologists Felix Warneken and Michael Tomasello have put toddlers in situations in which an adult is struggling to get something done, like opening a cabinet door with his hands full or trying to get to an object out of reach. The toddlers tend to spontaneously help, even without any prompting, encouragement or reward.

Is any of the above behavior recognizable as moral conduct? Not obviously so. Moral ideas seem to involve much more than mere compassion. Morality, for instance, is closely related to notions of praise and blame: we want to reward what we see as good and punish what we see as bad. Morality is also closely connected to the ideal of impartiality — if it’s immoral for you to do something to me, then, all else being equal, it is immoral for me to do the same thing to you. In addition, moral principles are different from other types of rules or laws: they cannot, for instance, be overruled solely by virtue of authority. (Even a 4-year-old knows not only that unprovoked hitting is wrong but also that it would continue to be wrong even if a teacher said that it was O.K.) And we tend to associate morality with the possibility of free and rational choice; people choose to do good or evil. To hold someone responsible for an act means that we believe that he could have chosen to act otherwise.

Babies and toddlers might not know or exhibit any of these moral subtleties. Their sympathetic reactions and motivations — including their desire to alleviate the pain of others — may not be much different in kind from purely nonmoral reactions and motivations like growing hungry or wanting to void a full bladder. Even if that is true, though, it is hard to conceive of a moral system that didn’t have, as a starting point, these empathetic capacities. As David Hume argued, mere rationality can’t be the foundation of morality, since our most basic desires are neither rational nor irrational. “ ’Tis not contrary to reason,” he wrote, “to prefer the destruction of the whole world to the scratching of my finger.” To have a genuinely moral system, in other words, some things first have to matter, and what we see in babies is the development of mattering.

Image Credit... Nicholas Nixon for The New York Times

Moral-Baby Experiments

So what do babies really understand about morality? Our first experiments exploring this question were done in collaboration with a postdoctoral researcher named Valerie Kuhlmeier (who is now an associate professor of psychology at Queen’s University in Ontario). Building on previous work by the psychologists David and Ann Premack, we began by investigating what babies think about two particular kinds of action: helping and hindering.