About 40,000 years ago the lives of Homo sapiens changed dramatically. Our ancestors developed group-hunting techniques and improved their weapons. This allowed them to kill much larger animals than they would have been able to individually. They developed tools for the making of other tools, and began a tradition of art that included cave paintings and clay sculptures. Did they just wake up one day and decide to develop a culture? Unlikely. How, then, did culture evolve?
Culture, as defined by social psychologists, refers to the set of traditions, beliefs, and practices that are passed from one generation to the next. Social learning, which involves observation and imitation of others, is the mechanism whereby culture is passed on.
“During the span of time that humans evolved, the environment was fluctuating more than it had before, and 11,000 years ago it stopped fluctuating,” said Dr. Joseph Henrich, an assistant professor of anthropology at Emory University, when he was at U of T recently.
Henrich described how social learning is favored when environmental changes are moderately fast (tens or hundreds of generations), in a 2003 paper in Evolutionary Anthropology, co-authored by Dr. Richard McElreath, of the University of California. With social learning, organisms can respond to these changes faster than can they could if they had to wait for their genes to evolve to help them survive (for example, by giving them sharp claws).
Furthermore, by using knowledge accumulated by others, individuals can spare themselves from having to learn this information by themselves. “Imagine yourself dumped into the Kalahari or the Atari desert. You wouldn’t be very well equipped for surviving in those environments. You would only be able to survive where you could find the locals and learn from them,” said Henrich.
A solitary individual in a completely novel environment would be forced to learn everything for himself. He would have to learn which foods are edible and which are not, how to obtain shelter and find water. Even these simple tasks would become extremely dangerous, and potentially deadly. The high cost of having to learn everything from scratch means that those who learn by cultural transmission are more likely to survive and pass on their knowledge in turn.
Over time the human mind was shaped to maximally exploit socially available information. Henrich said that it has done so in two ways. The first is conformist bias, where “an individual copies the majority, or moves towards the modal opinion.” The second is prestige-biased transmission, where some individuals copy the most skilled, successful, prestigious individuals.
Conformist bias “allows individuals to integrate partially informed other individuals…If everyone is partially informed, and we take the majority, we get the correct answer with a higher probability than from any one individual in the group,” said Henrich. Studies suggest that individuals should rely more on social learning if the situation is ambiguous, or the problem very difficult.
To illustrate the effect this has on human psychology, Henrich cited an experiment in which participants were shown an image of a suspect for either half a second or five seconds. Then they were given a line-up of four images, and told to pick the suspect out after hearing the responses of others. Participants were much more likely to give the wrong, conforming response when the information was inadequate (the half second viewing).
Prestige-biased transmission has also shaped the human mind to exploit social information. “If individuals evaluate cultural models (individuals they may learn from) and focus their social learning attention on those who are more successful, they will be more likely to acquire adaptive strategies,” wrote Henrich and McElrath. Individuals will pick others who are successful, and copy bundles of their traits (because one never knows which trait, or say a particular tool, prayer, or diet, led to their success).
The copying of bundles of traits is seen today in a number of social phenomena. Suicide rates increase, for example, after a celebrity suicide. “The [copy-cat] suicides match in age, sex, ethnicity, and method [and] these are not people who would have commited suicide anyway,” said Henrich. The effects of advertising are similar. What do celebrities really know about the products they advertise? No more than anyone else. However, because they are successful, they are copied.
