Craniology of Man and the Anthropoid Apes

Abstract

IN answer to Mr. A. T. Mundy's questions, it seems to me that it would be impossible in a young living ape, by artificial means, to prevent his frontal suture from closing, and if we could succeed in keeping it open I question if any marked increase in the size of the animal's frontal lobes would augment his intellectual capacity. It is not only the great size of man's cerebrum as compared with that possessed by anthropoid apes which gives him greater intellectual power, but, as I have stated in the passage quoted by Mr. Mundy from my Hunterian oration, the frontal and parietal lobes of the human brain are “far more perfectly developed than the corresponding lobes among anthropoid apes.” This is especially the case with respect to those motor and psychical areas of man's cerebral convolutions which control his power of intelligent speech; these areas of the brain are deficient in the anthropoid apes. It is probable that man's ability to make use of articulate language, and through this means to think, has led to the great development of the psychical elements of his brain. A comparison of the size and conformation of the cranium of Tertiary man with that of existing Englishmen is an indication of the length of time it has taken for the human cerebrum, and therefore intellect, to reach its present stage of evolution. Man and anthropoid apes we hold to be derived from a common ancestral stock; the former, under the action of natural selection and other causes, including, I think, not only an inherent capacity of cerebral but also of cranial growth, have gradually developed, whereas anthropoid apes, from arrest of cranial and cerebral growth, have not reached the standard attained by human beings; the difference between these two orders of beings, however, is one of degree, and not of kind.