In this article, the author proposes a new theory on what prompted the evolution of intelligence in a species, particularly humans. For 13 years, a group of field researchers observed wild orangutans in an isolated area of an Asian swamp (Kluat Swamp). These animals were unique because the area had a disproportionately higher number of orangutans than in the island's dryland forests. Unlike their forest counterparts, the orangutans created and wielded a variety of tools to look for and harvest food. Tool use was unique to the orangutans in this swamp area, even though similar food sources were present in the forests. Two things were unique to the group of orangutans: large numbers of animals in a small area and large numbers of adults spending time together, or what the authors call "tolerant proximity." Juveniles and other adult animals were observed to learn from more experienced tool-using and problem-solving adults. The author proposes the theory that culture (ie, social learning) favors the evolution of ever-increasing intelligence in a population over time.

COMMENTARY: The goal of the investigators was to try to arrive at another possible explanation of why humans evolved as the dominant species on this planet. Intelligence is clearly one of the reasons. The major take-home message for this reviewer is that learning is cultural and that it occurs via interaction with other members of a species. In other words, learning requires opportunities for "face time" with those in the know, be it for children, veterinary students, or new hires. And of course it argues strongly for attending those CE meetings! —Karen A. Moriello, DVM, Diplomate ACVD

Why are some animals so smart? Van Schaik C. SCI AM 65-71, 2006.