Among early hunter-gatherers, one of the fundamental characteristics that differentiated these humans from apes was routine food sharing, beyond initial parenting.
With virtually all such tribes long ago wiped out, anthropologists have a difficult time trying to study and understand the basic factors of cooperation and altruism underlying this effort at survival that is a hallmark of human evolution.
Seeking a model population, Alyssa Crittenden of the University of California at San Diego and colleagues ventured to northern Tanzania near the Serengeti to study arguably the last hunter-gatherers, the Hadza tribe.
They chose to focus on studying the Hazda children – who are capable as early as 5 years old to start collecting half their daily caloric needs.
Children are often overlooked in such studies, Crittenden said, but it is crucial to incorporate them into analyses to understand the early development of prosocial behaviors.
At the American Association of Physical Anthropologists annual meeting in Albuquerque, New Mexico, Crittendon presented results of the first phase of field work – which reflects the complexities of trying to understand the development of a simple characteristic like children sharing food on the plains of Africa.
Her colleagues included David Zes, a graduate student at the University of California at Los Angeles, and Frank Marlowe, an anthropologist at Florida State University in Tallahassee.
The study of two isolated camps found that “children are exhibiting altruistic behaviors at a very young age, with no supervision or direction from their parents.” The children also claimed no “teaching” on gathering food as they set out into the bush.
For more than a month, the team observed a total of 36 children [ages 2 to 17 years old] for 62 mid-day meals around communal campfires without adult supervision. Children maintained “absolute producer control” over the food to be shared, deciding whom to share with, how much and when.
In one camp at Gangidape, Crittenden’s team found selection of children and frequency of sharing was based on kinship, where children are more likely to share with relatives. But there was no reciprocity sharing with non-relatives, based on these other children returning the favor of sharing.
However, in the other camp, Siponga, the sharing results were the exact opposite. There wasn’t sharing with relatives, but there was sharing with non-relatives.
A possible explanation of the different results was that the second camp was smaller and some adults in it were limited in food-gathering capabilities due to disabilities.
“Food sharing networks of children are complex and variable,” says Crittenden. “The data suggests children are exhibiting altruistic behaviors at a very young age, with no supervision or direction.”
Such social networks among children must be considered in future studies of human evolution of altruistic behavior, she noted.