Chapter 8 Primate Models for Human Behavioral Evolution

Developmental Changes in the Skull of Chimpanzees and Humans (a) Chimpanzee and (b) Human. Anatomical differences arise through changes in regulatory genes in one or both species.

Human Origins and Behavior Primatologists still use nonhuman primate behavior to examine the evolution of human behavior, they also use statistical tests to examine relationships between variables.

Brain and Body Size The relationship between body and brain size is the index of encephalization. Modern humans have a brain size well beyond that expected for a primate of similar body weight. Allometry, also called scaling; is the differential proportion among various anatomical structures.

Cortex and Neocortex

Comparisons of Mammalian Brains

Language Human trait. –Some animals go beyond involuntary noise responses Vervet monkeys Symbolic Arbitrary

Language The bonobo Kanzi, as a youngster, using lexigrams to communicate with human observers.

Left Lateral View of the Human Brain Information that is to be used in speech is sent from Wernicke’s area, via a bundle of nerve fibers, to Broca’s area.

Evolution of Human Language

Primate Cultural Behavior Cultural behavior makes primates attractive as models for behavior in early hominids.

Culture is Learned (a) This little girl is learning how to use a computer by watching her older sister. (b) A chimpanzee learns the art of termiting through intense observation.

Using Tools Chimpanzees in Bossou, Guinea, West Africa, use stones as hammer and anvil to crack oil-palm nuts. The youngster is learning to use stone tools through observation.

Criteria for Cultural Acts in Other Species Innovation Dissemination Standardization Durability Diffusion Tradition Nonsubsistence Naturalness

Aggressive Interactions Members of a chimpanzee “border patrol” at Gombe survey their territory from a tree.

Altruism Behavior that benefits another while involving some risk to the performaer

The Primate Continuum Human brains are larger than primate brains, but the neurological processes are functionally the same.