MELISSA BLOCK, Host:
Now to another question of our existence. Humans have succeeded in ways that other species usually don't by sharing, but we're not born with a sense of egalitarianism. So when does it develop? NPR's Jon Hamilton reports on a new study that may have found the answer.
JON HAMILTON: Kids get a lot of advice about sharing from parents and stories and even songs.
(SOUNDBITE OF MUSIC)
BLOCK: (Singing) It's mine, but you can have some. With you I like to share it because if I share it with you, you'll have some too.
HAMILTON: Fine, but that's not the way a typical three-year-old sees it. Scientists learned that when they studied more than 200 Swiss children between the ages of three and eight.
In one experiment, kids got two pieces of candy. They had to decide whether to keep both pieces or give one to another child. The three- year-olds were pretty consistent.
MICHAEL TOMASELLO: They tend to go for the two-for-me, zero-for-you more often.
HAMILTON: Michael Tomasello is at the Max Planck Institute for Evolutionary Anthropology in Germany. He wrote an analysis of the Swiss study in this week's issue of the journal Nature.
Tomasello says the three-year-old children acted like chimpanzees when it came to sharing. They were selfish. But chimps remain selfish, while kids change dramatically as they get older.
Tomasello says nearly half of the eight-year-olds in the Swiss study decided to share their candy.
TOMASELLO: That is the classic sense of fairness, that I'm giving up something myself, I'm inhibiting my selfish motives, and I'm going for fairness.
HAMILTON: Tomasello says it's not clear what's causing kids to change their behavior. One possibility is that they're actually paying attention to all those sharing songs and lessons from their parents.
TOMASELLO: Children have a fair number of experiences with adults where there are three cookies and there are two kids, and so the adult gives each of them one and then divides the second one in half so that they each have the same.
HAMILTON: But there may be something else going on, says James Fowler of U.C. San Diego
JAMES FOWLER: So it could be that part of the developmental story is that we are, in some sense, hard-wired to develop this egalitarianism as we get older.
HAMILTON: Fowler says by the age of eight, children have developed empathy, the ability to see things through someone else's eyes, and that means they tend to feel goof if they make someone else happy, by, say, giving them a piece of candy. But the children in the study didn't share candy with just anyone. They were much more likely to share it if the recipient was someone they recognized rather than a stranger. Fowler says that suggests an evolutionary explanation for sharing.
FOWLER: Groups that share with one another do better than groups that don't share with one another, and this could be part of the reason that this behavior evolved in the first place.
HAMILTON: Fowler says that whatever the reason, sharing gets a lot of attention in modern society. He was reminded of this while listening to speeches from the Democratic National Convention.
FOWLER: Everyone deserves an equal opportunity, that we're the party that shares, that we're going to make sure that no one is too rich and no one is too poor. Over and over again, egalitarianism permeates politics.
HAMILTON: Of course that's just theoretical sharing. No one has to actually give away any candy until after the election.
Jon Hamilton, NPR News.
NPR transcripts are created on a rush deadline by Verb8tm, Inc., an NPR contractor, and produced using a proprietary transcription process developed with NPR. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.