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In our last episode...
We discussed thought vs. intelligence, and had discussed lab rats, lassie and dolphins. But what about primates?
For intelligence purposes, we tend to divide primates into 3 groups: monkeys, great apes and humans. The human category is rather obvious, but to be explicit, it includes homo sapiens sapiens (modern man) as well as all of the obvious precursors: homo sapiens (Cro Magnon), homo neanderthalensis, homo habilis, etc. Great apes include chimpanzees, bonobos (also called pygmy chimpanzee), gorillas, orangutans (and sometimes includes gibbons). The human and great apes share characteristics of being large, tailless primates, capable of walking erect, live in family groups, are omnivorous, they are sexually dimorphic, with limited characteristics of reproductive *heat*, and 8-9 month pregnancy usually yielding one offspring.
Monkeys are basically everything else in the Primate taxonomical order. They are distinct from apes in size, gestation, walk on all fours instead of erect, and most have tails. New World Monkeys have prehensile tails (capable of grasping) while Old World Monkey tails are not prehensile.
Are monkeys intelligent? Certainly they seem to be. They can solve puzzles, use tools and operate on memory. Many behaviors are *emergent* (they "emerge" during experience) and do not *need* operant training to learn a task - many times they can learn the task simply by watching another monkey do it. Do they think? Well, the problem is that we really have no way of knowing.
But with the great apes, we do have a way of knowing if they think. The Great Ape Project, the work of Jane Goodall, Francine Patterson, Beatrix T. and R. Allen Gardner, and of David Premack have all given us a glimpse of language use by the Chimpanzee Washoe, Gorillas Koko (Patterson, F.G.; Linden, E. 1981, The education of Koko, New York: Holt, Rinehart and Winston), and chimpanzees Sarah and Nim (Premack, David & Premack, Ann James. 1983, The Mind of an Ape). With the help of American Sign Language, and other symbolic tools, these Great Apes can communicate back with the scientists that study them.
Such communication clearly demonstrates a sense of self-identity, motivation, awareness of surroundings, wants, needs and even emotions. However, critics of assigning "thought" to nonhuman primates point out that the Great Apes learn their language very slowly, and many not at all. In addition, a key lack in the communication is that the subjects do not initiate their own interrogatives - in other words, they do not ask questions - as any human two-year-old might. Supporters attribute these shortcomings to problems with applying human standards to nonhumans.
On the other hand, what *other* standards do we have to apply?
It's a tricky question, and one not easily answered in psychological terms, but we do have recourse to a brain science answer. The key differences in human and Great Ape brain vs monkey brain is the size and development of the Frontal Lobe (prefrontal areas) and Temporal Lobe. Thus the brain areas responsible for executive function, memory and many of the processes we believe underlie thought, are more highly developed in humans and our near cousins, the Great Apes. Therefore, if any nonhuman species are likely to "think" it would be among the apes.
This now leads us into the realm of consciousness and sentience, which we will cover next in The Lab Rats' Guide to the Brain!