7 September 2007

Guess Who's Coming To Dinner?

By Rusty Rockets

Our hairy primate relatives have highly developed intelligence and social skills, as evidenced by their tool usage and hierarchical social order. But what about social intelligence? Could an opposable-thumb challenged chimp pass muster at a human social gathering?

So far, nobody seems to have noticed the chimp (let's call him Lance) that you've brought along - in the name of science - to the family get-together. The other guests think Lance is a particularly ugly child, but how long can this charade last? While both a young child and a chimp can deliver a lot of noise and wanton destruction, sooner or later they will have to exhibit their socio-cognitive skills. How a primate would fair in such a situation, compared to a human, has been a central issue for researchers for years. So, could Lance pass muster?

First of all, it should be explained that humans are believed to have many social-cognitive skills that other closely related primates do not, as predicted by the "cultural intelligence hypothesis." This hypothesis posits that during early development a species is equipped with a species-specific set of social-cognitive skills (interacting with beings and their intentional actions, perceptions, and knowledge), which basically helps us to avoid becoming embarrassing social pariahs among our own species.

The hypothesis also states that there should be a point in early development - before a child's exposure to writing, symbolic mathematics, and formal learning - at which a child's physical cognition (interacting with inanimate objects) is comparable to our nearest primate relative.

So researchers recently set about testing the cultural intelligence hypothesis, which involved pitting over 100 chimps and 30 orangutans (ranging in age from 3 to 21) against an equal number of toddlers in a battle of cognitive wits. "We compared three species to determine which abilities and skills are distinctly human," explains Esther Herrmann of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. The researchers claim that such a cognitive comparison has never before been undertaken. The comparison involves subjecting the three groups to the Primate Cognition Test Battery (PCTB), which is designed to identify the division between social and physical cognition.

After listening to Herrmann's team you'd expect the non-human primates to perform quite well against the toddlers, as they need both highly developed intelligence and social cognitive ability to survive in their natural habitat. "To locate food, primates need cognitive skills for dealing with 'space,' to choose wisely among multiple food sources, they need social skills for dealing with "quantities"; and for extracting food from difficult places," the team writes in a subsequent study paper, published in Science.

Such cognitive traits have been observed in another study, published in the journal Animal Cognition, where non-human primates seek out distant, but bountiful food sources, despite the closer proximity of less generous ones.

As far as social cognition goes, this ability evolved as a result of an array of competing cooperative and competitive behaviors. "To manipulate the behavior of others, primates need skills of 'communication', to learn things vicariously from observing others, they need skills of 'social learning'; and to predict the behavior of others in competition, they need cognitive skills for understanding psychological states such as goals and perceptions."

Additionally, the Animal Cognition study reveals a certain degree of social cognitive sophistication. The researchers found that food source decisions could "be based on value judgments of resource sites that take into consideration social as well as dietary needs and preferences," says Elena Cunningham, from the State University of New York. "The monkeys' foraging decisions may help to keep the group together." In their totality, these non-human primate physical and social cognitive skills seem very close, if not identical, to human abilities. But let's take a look at one of the PCTB tests and see what resulted.

One of the social learning tasks involved a researcher demonstrating how to flip open a plastic canister in order to access some food or a toy housed inside. The task was designed to show whether a subject was capable of learning and then performing a series of goal-oriented actions. With their highly developed social cognitive abilities kicking into action, the toddlers watched and successfully copied the researcher. "Social cognition skills are critical for learning," says Herrmann. But the chimps and orangutans, on the other hand, ignored the researcher's method and instead tried to retrieve their reward by breaking the canister, or pulling at it with their teeth. "The children were much better than the apes in understanding nonverbal communications; imitating another's solution to a problem and understanding the intentions of others," says Herrmann.

On the issue of physical cognition, however, there was little difference between the toddlers and the non-human primates, which goes a long way in supporting the hypothesis that humans have developed some special aptitude for social cognition; the cultural intelligence hypothesis. But just because our primate relatives didn't do so well on comparative social cognitive tests doesn't mean that they are socially inept. In fact, another article published in the same edition of Science points to how non-human primates seek out rationality, and can predict the intentions and behaviors of others (including humans).

In that study, led by Justin Wood from the Department of Psychology in the Faculty of Arts and Sciences at Harvard, primates were presented with two possible food containers. A researcher would then either deliberately grasp a container, or "accidentally" come into contact with it. Of the three species of primate being tested (old and new world monkeys, and apes), all of them showed preference for the container that had been decisively grabbed. Wood deduced that the primates distinguished between the goal-oriented action of the experimenter, and an accidental action. A second experiment was also conducted, using the same two food containers, where an experimenter, with both his hands full, would touch one of the containers with his elbow. Then with his hands empty, the same experimenter would again touch a container with his elbow. The primates showed that they could see the rationality behind touching a container with an elbow while a person's hands were full, but could not when they were empty.

"A dominant view has been that non-human primates attend only to what actions 'look like' when trying to understand what others are thinking," says Wood. "In contrast, our research shows that non-human primates infer others' intentions in a much more sophisticated way. They expect other individuals to perform the most rational action that they can, given the environmental obstacles that they face."

Respectively, the two major studies show, fairly conclusively, that humans really are the social sophisticates of the primate world, and that our ability to infer others' intentions dates back millions of years. But what does this mean as far as trying to pass off Lance at a social gathering? Well, he probably wouldn't win any social etiquette awards. But then, I think we all have relatives like that.

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