Monday, December 3, 2007

A Zombie’s Inquiry Into the Evolution of his Most Favorite Meal III: What are Humans Good at?

Except running away from poor, starving zombies, that is (– the Selfish Bastards!)

A while back Juan Uarigerika wrote an article in Seed magazine about language evolution. In it he proposed that maybe language is responsible for most of our especially human intelligence, as well as precursor for our more advanced sensorimotor capacities, and that in the end it could turn out that research into our cognitive architecture would come up with the formula ‘Finch + Chimp = Human.’ Uarigerika’s article is written, for a magazine, so it’s clear that he doesn’t really do much in order of presenting evidence and arguments in a really ‘scientific’ way but rather presents his ideas in a in a popular style, but still I think his proposal is quite problematic (Mark Liberman has written a nice rebuttal of Uarigerika’s reductionsit view over at Language Log)

funny pictures
moar funny pictures

A better way to study the differences between human and animal cognition effectively is to compare differences and similarities of certain cognitive traits and analyze how these may come about and how the cognitive function in question is enabled in the given organism.
In a massive comparative study, Hermann et al. (2007) had Chimpanzees, Orangutans and 2.5 year-old children perform various task and then evaluated and compared the species’ qualitatively differing performances. The tasks were divided into two “domains”, physical and social, each consisting of three “scales” (physical: space, quantitiy, causality; social: social learning, communication, theory of mind). Among the 20 tasks there were such things as “using a stick in order to retrieve a reward which is out of reach.” (causality), “Locating a reward.“ (space), “Solving a simple but not obvious problem by observing a demonstrated solution” (social learning), “Following an actor’s gaze direction to a target” or “Understanding what an actor intended to do (unsuccessfully” (both Theory of Mind).

On average, the results of humans and chimpanzees were very similar in the physical domain, and scored much higher than the orangutans. In the social domain, however, humans outperformed chimpanzees and orangutans by far. The non-human apes were right only half as often as the human children. This means that chimpanzees outcompete orangutans when it comes to things as causal reasoning and quantities, but are equally bad at imitating others or assessing their intentions. Whereas in the physical tasks chimps sometimes performed better than humans (e.g. Tracking of a reward after location changes or Using a stick in order to retrieve a reward which is out of reach, something where human children performed much worse than both chimps and orangutans), interestingly
“Children were better than both ape species at the three causality tasks in which a judgment must be made before manipulation or choice, whereas chimpanzees were better than children and orangutans at the one causality task involving active tool use.” (Hermann et al. 2007:1362)
as well as in regard to inhibitory control, which could partly be due to the prominence and dominance of prefrontal circuitry in the human brain and its importance in cognitive control— “the ability of the brain to coordinate processing mong its millions of neurons in order to direct them toward future goals.” (Miller et al. 2002: 1131) — which I alluded to in my earlier posts.

Chimps and orangutans both performed a little better than human children when it came to “Producing communicative gestures in order to retrieve a hidden reward.”, which was the only social domain task in which the difference between the human and non-human primates wasn’t significant. The authors conclude that
“the current results provide strong support for the cultural intelligence hypothesis that human beings have evolved some specialized social-cognitive skills (beyond those of primates in general) for living and exchanging knowledge in cultural groups: communicating with others, learning from others, and “reading the mind” of others in especially complex ways“ (Hermann et al. 2007: 1365).
But they caution against the conclusion that social intelligence as a whole, or a “Theory of Mind-module” is the distinctive property separating humans, chimps and orangutans. Instead, taking into account that human children were better than chimps in causality tasks that didn’t include the active manipulation of tools, they speculate that
“what may be distinctive is the ability to understand unobserved causal forces in general, including (as a special case) the mental states of others as causes of behavior. Even in this case, however, it is a plausible hypothesis that understanding hidden causal forces evolved first to enable humans to understand the mental states of other persons, and this generalized only later to the physical domain.”
Which fits well with the evidence that humans are especially good at displaced mental and conceptual simulation (Miller et al. 2002, Barsalou 2005) and such things as mental time travel (Gilbert & Wilson 2007).
In my next post I will expand a bit on complementary approaches to comparing human and other non-human primate cognition and differences in general.


Barsalou, Lawrence W. 2005. “Continuity of the conceptual system across species.” Trends. Cog. Sc. 9.7: 309-311.

Gilbert, Daniel T. and Timothy D. Wilson. 2007. “Prospection: Experiencing the Future.” Science 317: 1351-1354.

Hermann, Esther Josep Call, María Victoria Hernández-Lloreda, Brian Hare, and Michael Tomasello. 2007. “Humans Have Evolved Specialized Skills of Social Cognition: The Cultural Intelligence Hypothesis” Science 317: 1360-1366.

Miller, Earl K., David J. Freedman and Jonathan D. Wallis 2002. “The Prefrontal Cortex: Categories, Concepts and Cognition.” In: Phil. Trans. R. Soc. Lond. B 357: 1123–1136

No comments: