The Evolution of Cultural Evolution

In 1860, aiming to be the first Europeans to travel south to north across Australia, Robert Burke led an extremely well-equipped expedition of three men (King, Wills and Gray) from their base camp in Cooper’s Creek in central Australia with five fully loaded camels (specially imported) and one horse. Figuring a maximum round trip travel time of three months, they carried twelve weeks of food and supplies. Eight weeks later they reached tidal swamps on the northern coast and began their return. After about ten weeks their supplies ran short and they began eating their pack animals. After twelve weeks in the bush, Gray died of illness and exhaustion, and the group jettisoned most of their remaining supplies. A month later, they arrived back in their base camp, but found that their support crew had recently departed, leaving only limited supplies. Still weak, the threesome packed the available supplies and headed to the nearest outpost of “civilization,” Mt. Hopeless, 240km south. In less than a month, their clothing and boots were beyond repair, their supplies were again gone, and they ate mostly camel meat. Faced with living off the land, they began foraging efforts and tried, unsuccessfully, to devise means to trap birds and rats. They were impressed by the bountiful bread and fish available in aboriginal camps, in contrast to their own wretched condition. They attempted to glean as much as they could from the aboriginals about nardoo, an aquatic fern bearing spores they had observed the aboriginals using to make bread. Despite traveling along a creek and receiving frequent gifts of fish from the locals, they were unable to figure out how to catch them. Two months after departing from their base camp, the threesome had become entirely dependent on nardoo bread and occasional gifts of fish from the locals. Despite consuming what seemed to be sufficient calories, all three became increasingly fatigued and suffered from painful bowel movements. Burke and Wills soon died, poisoned and starved from eating improperly processed nardoo seeds. Unbeknown to these intrepid adventurers, nardoo seeds are toxic and highly indigestible if not properly processed. The local aboriginals, of course, possess specialized methods for detoxifying and processing these seeds. Fatigued and delusional, King wandered off into the desert where he was rescued by an aboriginal group, the Yantruwanta. He recovered and lived with the Yantruwanta for several months until a search party found him. The planning for this expedition could not have been more extensive, and these men were not unprepared British schoolboys out on holiday. However, despite their big brains, camels, specialized equipment, training, and seven months of exposure to the desert environment prior to running out of supplies, they failed to survive in the Australian desert. This bit of history makes a simple point: Humans, unlike other animals, are heavily reliant on social learning to acquire large and important portions of their behavioral repertoire. No evolved cognitive modules, “evoked Joseph Henrich received his Ph.D. in 1999 from the University of California, Los Angeles, and is currently Assistant Professor of Anthropology at Emory University. He was recently a fellow in the Society of Scholars at the University of Michigan and at the Institute for Advanced Study in Berlin. He has conducted ethnographic and experimental research among the Machiguenga of Peru and the Mapuche of southern Chile. His theoretical work has involved constructing formal models of the evolution of cultural learning capacities, cultural evolution, and culture-gene coevolution. E-mail: [email protected] Richard McElreath received his Ph.D. in 2001 from the University of California, Los Angeles, and is now Assistant Professor of Anthropology at the University of California. He was recently a postdoctoral fellow at the Center for Adaptive Behavior and Cognition, Max Planck Institute for Human Development, Berlin. He conducts ongoing field work to investigate cultural microevolution among several ethnic groups in southwest Tanzania. E-mail: [email protected]