THE EVOLUTION OF HUMAN INTELLIGENCE. SOME REASONS WHY IT SHOULD BE A CONTINUING PROCESS.

There are now many experiments with man which give reality to the concept that all human behavior must have some kind of direc or indirect connection with the genetics of the reacting person.

Abstract

There are now many experiments with man which give reality to the concept th t all human behavior must have some kind of direc or indirect connection with the genetics of the reacting person. A stimu lating review by Gottesman (1963) covers most of the recent develop ments in this area of research. The clamor resulting from the nature-nurture misunderstanding seems to have frequently obscured the obvious relationship between the evolu tion of the cerebral hemispheres and the basic intelligence of each species. The chimpanzee is smarter than the cat, and the cat is brighter than the canary. The very readable article by Bitterman (1965) shows that the intelligence of animals on various rungs of the evolutionary ladder differs not only in degree but also in quality. The correlation between the evolutionary increase in the size of the brain and the elaboration of intelligence is excellent. One can observe the astonishing expansion in size and efficiency of the forebrain from the modest organs of our insectivorous-like ancestors to the incredible mental equipment of Homo sapiens, man the wise. Increases in the size of the whole body should not be mistaken for increases in intelligence. Those terrible lizards, the dinosaurs, provided a splendid example of a remarkable response of body size to the pressures of natural selection, accompanied by an almost complete failure of the brain to keep pace with the evolutionary luxuriance of the other organs of the body. There will be no attempt to define intelligence in this paper. The word is used in the same general sense as people use it everywhere. We can present some useful concepts without any concern for the validity of particular tests of intelligence or the reliability of the findings for particu lar individuals. The only required profession of faith from the reader is that each person is the product of the interaction of his biology (genetics) and his environment.