Highlight
Teaching and Sharing May Have Set Early Humans Apart from Apes
Cultural transmission in hunter-gatherer adolescence: Aka aunt teaching niece to make basket (photo by Bonnie Hewlett)
Achievement/Results
What accounts for the huge differences we see between apes and humans? It has long been understood that humans have an ability—seemingly lacking in apes—to maintain and build on the knowledge and skills of previous generations. But some anthropologists have claimed that teaching—the most likely way to accumulate skills from generation to generation—is not practiced in contemporary hunter-gatherers. If such societies accurately represent very ancient human societies, then how could cultural change begin to accumulate tens or hundreds of thousands of years ago, as we know it did?
Washington State University (WSU) professor Barry Hewlett and recent Ph.D. student Adam Boyette provide preliminary data from the Central African Republic (CAR) suggesting that teaching is in fact very important among hunter-gatherers. Boyette provides the first observational study of teaching in middle childhood in a hunter-gatherer group and demonstrates that Aka (hunter-gatherer) children learn through a variety of behaviors that fit the functional, evolutionary definition of teaching: a behavior that helps another acquire adaptively-relevant information at a cost to the teacher. Boyette won the Student Paper Prize from the Evolutionary Anthropology section of the American Anthropological Association in 2012 for his paper on hunter-gatherer social learning.
But what about teaching and learning among apes? One aspect of learning via teaching has been called precise (or over-) imitation. This means copying irrelevant features of a task. This is a distinctive feature of cumulative culture in humans because it contributes to high fidelity in our transmission of culture. Another WSU graduate student working with Hewlett, Richard Berl, has shown that apes consistently do not over-imitate while children from several Western countries do over-imitate. (Interestingly, Aka children do not over-imitate, even though Aka adults do.) This provides another bit of evidence for the importance of teaching in allowing human ancestors to gradually outpace apes in cultural elaboration. These studies have been funded in part by a National Science Foundation Integrative Graduate Education Research and Traineeship (IGERT) grant to Washington State University and the University of Washington (UW) to provide training to PhD students in evolutionary modeling. The project, directed by WSU archaeologist Tim Kohler and UW anthropologist Eric Smith, completed in May 2013.
The IGERT provided some support for two field stations in Africa—an established station in the CAR and a new field station in Ethiopia. These field stations enabled three IGERT faculty and three student trainees to test a variety of hypotheses that cut across biology and anthropology. For instance, in spring 2013 Richard Berl collected both genetic (saliva samples) and cultural data (through interviews) to develop mathematical models of gene-culture interactions of hunter-gatherers and neighboring farmers at the new field site in Ethiopia.
Hewlett, who is preparing an article about hunter-gatherer teaching in infancy, uses videotapes of hunter-gatherer infants to demonstrate that a wide variety of teaching methods are used to transmit diverse skills and knowledge very early in life. Another gulf that separates apes and humans is sharing practices, which are common and varied in human societies but extremely limited among apes. Adam Boyette is using mathematical modeling and cultural anthropology methods to examine sharing among hunter-gatherers across their life course. Boyette reports that forager children share resources more frequently than farmer children from as young as four years of age, supporting a cultural-evolutionary origin for differences in human sharing behavior. He also finds that increases in sharing in adolescents and young adults among the Aka focus on cigarettes and meat—both highly valued resources. Such sharing is particularly common among adolescent males, supporting arguments that human resource sharing may have evolved as a signal of quality to potential mates and allies.
The IGERT also provided outreach funds to enable African scholars to participate in this research and receive training in evolutionary biocultural approaches. For instance, J. P. Nganga, one of two archaeologists in the CAR, traveled to WSU to acquire basic skills and knowledge in evolutionary approaches to archaeology. He now incorporates these approaches into publications with former WSU (now SMU) faculty member Karen Lupo.
For Further Reading:
Hewlett, B.S., H.N. Fouts, A.H. Boyette and B.L. Hewlett 2011. Social learning among Congo Basin hunter-gatherers. Philosophical Transactions of the Royal Society B (U.K.) 366: 1168-1178.
Lupo, K., J. P. Ndanga, and C. Kiahtipes, in press. Late Holocene population interactions in the Northwestern Congo Basin. In B. Hewlett (ed) Hunter-Gatherers of the Congo Basin: Culture, History and Biology of African Pygmies. Piscatawy, NJ: Transaction-Rutgers—The State University of New Jersey.
Address Goals
The frontier of knowledge that we aim to advance with this research is knowledge about the behavioral factors—not just the physiological factors—that may have contributed to divergence of the groups that became the ancestors of all humans, and those that became the ancestors of apes. Knowledge of the possible importance of teaching and sharing in this divergence provides us with a needed perspective on the fundamental importance of these behaviors to our humanity. In this way, expanding our nation’s scientific literacy can also expand their humanity.
