Lecture 19: Intelligence in Monkeys, Apes and Humans

EEB 210 Spring 2008

Lecture# 17: Intelligence in Monkeys, Apes and Humans

Cognition: thinking, social learning

Evidence suggests that apes have greater cognitive abilities than monkeys----may have been a major step in evolution of cognitive abilities

Differences between monkeys and apes in using technology: Chimps are best tool users of all animals---use rocks to break open nuts---use wands of grass to probe for ants and termites

Among primates, only chimps and orangutans frequently use tools in the wild---gorillas also known to use tools in captivity

One report of capuchin monkeys using rocks to smash nuts and some monkeys throw branches at predators, but tool using not often seen in monkeys

Theory of Mind: being able to take into account another individual’s mental state

Apparently this capacity takes some time to develop in humans---child may cover its eyes and think that others cannot see her/him---or child sees a movie and assumes that its parents knows about the content of the movie too (this common even up to 6-7 years of age)

Chimp will warn companion of impending danger if the companion is unaware (unable to see the danger), but will not give warning to a companion that is aware---for example, if chimp A sees veterinarian coming and chimp B cannot, then A warns B---but if both A and B can see the veterinarian approaching they don’t warn each other--- Monkeys don’t seem to make this distinction. Chimps have also been seen to hide a prized object (novel food) when others are not watching.

Chimps both in the wild and in captivity appear to show empathy---In one instance a predator killed a chimp and adults found the body---they did not allow juveniles to approach the body except for one sibling of the dead chimp

Monkeys actually seem to encode more than apes in their vocal communications, but apes used gestures more

Iconic gestures indicate an action that should be taken (for example, a twirling motion with the hand could be used to indicate to another individual that he/she should turn around; pointing might be used to indicate that someone should look in a certain direction) 2

Enculturated great apes: Ai is an enculturated chimp that has been trained to do problems that involve matching of symbols---when correct responses are made, tokens come out of the computer and Ai can use these in a vending machine to get snacks---Ai’s son, Ayuma, was never trained by humans but he appeared to have learned by observing his mother: symbol for brown flashed on the screen, then he had to choose between a brown and a pink square---he very deliberately reached to touch the brown square

Part of great ape’s adaptation is to use social learning

Models for development of hominin characteristics:

a. referential models---choose a species that for various reasons is considered to be most like an ancestral hominin with respect to behaviors---for many years, baboon was considered the best model because it lives in a savanna environment similar to what early hominins probably evolved in

b. phylogenetic models---do not rely too heavily on any one living species---for example, humans are about equally related to chimps and bonobos, and these species differ in certain behaviors (i.e., chimps hunt but bonobos don’t; chimps more aggressive toward each other than bonobos)---gorillas and orangutans also do not hunt and are very largely vegetarians (occasionally eat insects)

c. conceptual models---does not focus on particular types of primates, but rather on processes---so, for hunting, any type of primate that hunts may be considered as potentially of interest to understand early hominin hunting

Concept of teaching. Humans learn by imitation, but they also teach. Apes do not appear to teach. For example, a young chimp may attempt to imitate its mother’s technique to crack nuts by placing the nut on a rock and hammering it with another rock. But the mother does not appear to pay attention to her offspring’s efforts. If the young chimp places the nut on the ground instead of on a rock, the mother makes no attempt to correct its technique. Chimp infants do appear to learn more from their mothers than monkey infants do; however, it has been suggested that none of the non-human primates actively teach each other anything

For some interesting video clips of chimps performing learning and tool using tasks, go to Ai’s home page at: www.pri.kyoto-u.ac.jp/ ai /index-E.htm Click on videos from column at left