Monday, August 22, 2005

Culture and Chimpanzees

Culture is one of the seminal concepts in anthropology. A lot of people have tried to define it. Starting with E. B. Tyler (one of the founding fathers of anthropology) who defined culture thusly:

"culture or civilization, taken in its wide ethnographic sense, is that complex whole which includes knowledge, belief, art, morals, law, custom, and any other capabilities and habits acquired by man as a member of society"

Others, such as Linton defined culture this way:

"...the sum total of ideas, conditioned emotional responses, and patterns of habitual behavior which the members of that society have acquired through instruction or imitation and which they share to a greater or lesser degree..."

Perhaps one of the best definitions of culture - well more a list of the characteristics that define a culture - was given by Murdock in his 1940 paper for the American Sociological Review entitled "The Cross Cultural Survey". Murdock found that culture could be characterised by the following traits:

1) Culture is learned - that is it is not instinctive or biologically transmitted but is acquired by each individual through their life experiences.
2) Culture is inculcated - The above are transmitted from parent to child over successive generations. This means that not only are techniques and knowledge imparted but mistakes are corrected as well. Consequently, there is a certain amount of indepoedence between the traits being passed and the individual bearers of culture.
3) Culture is social - in other words it is shared between individuals living in groups and is kept uniform via social pressure.
4) Culture is ideational - that is certain kinds of behavior should conform to established precedent. Put another way, there are certain ideal norms or patterns of behavior (think mental template)that the bearers can use to guide their behavior.
5) Culture is gratifying - that is it satisfies - or provides a means for satisfying - biological and psychological neads
6) Culture is adaptive - to both the geographic and social environment
7) Culture is integrative - In other words, the elements of a given culture tend to form an integrated whole - although historical events - such as improved technology - exert a disturbing influence.

One could, and many people have, argue with most of these definitions. There are, however, certain commonalities in most definitions of culture. Especially, the parts about culture being shared and learned. For the longest time, cultural behavior was restricted to humans (implicit in E. B. Tylor's definiton above). For example, it used to be thought that tool use (ala Oakley's "Man the Tool-maker)was a cultural trait restricted to humans. Then tool use among chimps was discovered. Language was another cultural characteristic that - it was thought- resided only in humans. Indeed, most definitions of culture (See Kroeber and Kluckhohn's 1952 book "Culture: A Critical Review of Concepts and Definitions" for over 200 definitions collected from the literature) state overtly or imply that language, and it's ability to transmit acquired knowledge, is necessary for culture to exist. Then it was discovered that chimps, gorillas and orangs could use sign language.

A recent study at the Yerkes National Primate Research Center has cast an interesting light on culture. Researchers devised an ingenious experiment to study cultural transmission in chimps. Rather than trying to create an artificial situation like you see in some of the language experiments (usually with one chimp in isolation), researchers decided to test chimps in a group situation:

In the study, researchers introduced a naturalistic foraging task into three groups (two experimental and one control) to see if chimpanzees can learn by observation. While unseen by other chimpanzees, researchers taught a high-ranking female from each of the two experimental groups a different way, either Lift or Poke, to retrieve food from a system of tubes called Pan-pipes. Once the two females mastered the task, other chimpanzees within their groups were allowed to watch them perform the new skill over a seven-day period before all group members were allowed to use the tool. According to the researchers, group members gathered around the local expert, watched attentively and proved successful when allowed to try the task on their own. The third group, which did not have the benefit of a local expert and was left to decipher the task on its own, was unsuccessful in retrieving food from the Pan-pipes.

The upshot is that:

"This study demonstrates apes do copy members of their own species and they develop different traditions by doing so," said Dr. Horner. "It makes it likely differences in tool use between wild chimpanzee communities in Africa indeed reflect a form of culture and establishes another link between human and chimpanzee societies."

Occassionally, chimps that learned Poke would discover Lift, try it a few times, then revert to Poke. Ditto for chimps that learned lift. This has been taken to indicate a conformity bias among chimps every bit as strong as that among humans:

The conformity bias finding was an unexpected, but equally important, result of this culture study, according to Dr. Horner. A few members of each group independently discovered the alternative method for freeing food from the Pan-pipes, but this knowledge did not endanger the groups' traditions because most of these chimpanzees reverted back to the norm set by their local expert. "Choosing the group norm over the alternative method shows a level of conformity we usually associate only with our own species," said Dr. Horner. "By using the group's technique rather than the alternative method, we see the conformity is based more on a social bond with other group members than the simple reward of freeing the food."

But think about it in terms Murdock's definition of culture given above. The different methods of getting the food were learned, certainly social in that the techniques were shared among members of the group, ideational in that each group had a mental template or norm to guide their behavior, gratifying in that biological needs were satisfied, and adaptive. Whether, the behavior was inculcated, in the sense mentioned above, and integrative remains to be seen because the experiments were short term and you would need a long term study to decide those two questions. What about conformity - something getting this study a lot of attention? According to the study:

A characteristic traditionally thought to be solely human, the propensity to conform, may be part of an evolutionary progression. "These results suggest an ancient origin for the cultural conformism that is so evident in humans," said de Waal. "Further research may reveal these findings to be more widespread throughout the animal kingdom."

One thinks that here people are confusing the modern, stereotypical definition, of conformism ("Like, gaw'd Levi's are soo 15 minutes ago...") with the ideational aspects of culture. Although, in most cultures social pressure can be exerted to insure uniformity, there is room for ideosyncratic behavior. Incidentally, the studies doesn't mention whether or not social means were used to induce conformity. It just says that the chimps that discovered alternate means reverted back to the norm of their group, i. e. the mental template for getting food that they already had.

Interestingly enough, the New Scientist article mentions that the poke method was more efficient at getting food than the Lift method. Chimps that learned Lift but discovered, independently, Poke reverted to Lift. I would like to see more on this before I chalk it up to "conformity", especially because of the way the study is portrayed. "Copycat chimps are cultural conformists" is the title of the New Scientist article. The Science Daily title is better but in reading both pieces I don't get the feeling that the authors really understood the concepts they were discussing.

Leaving the conformity issue aside, what this study does indicate is that we have to look far back in human history to discover the origins of culture - and this study certainly prooves that chimps are culture bearing organisms. It goes without saying that the implications of this study for our understanding the behavior of Australopiths and early Homo will probably need to be revised somewhat.

Cool stuff!