U PREFACE 



J^ This little volume grew out of the thirty-eighth James Arthur Lecture 

 on the Evolution of the Human Brain, which I delivered at the American 

 Museum of Natural History, New York City, on 30 April 1969. There are 

 many ways to approach brain evolution, including the electrophysiological, 

 comparative, ontogenetic, and neurochemical. My choice of a direction, 

 conditioned by my own background as an anatomist and palaeoanthro- 

 pologist, fell on "Some Aspects of the Fossil Evidence on the Evolution of 

 the Hominid Brain." This choice confined me to two phases: the gross 

 external morphology of the brain (as reflected by the modeling of, and 

 markings on, the interior of the braincase and by endocranial casts, natural 

 and artificial) and the tangible evidence of what hominids could do with 

 their brains, in the form of artefacts and other cultural objects. 



The study of gross external morphology was further circumscribed: 

 it was confined to the measurable. Of all the quantifiable aspects of the 

 brain, its overall size is perhaps the parameter that can be determined most 

 readily and most objectively. Moreover, brain size is highly relevant for 

 such a study as it shows evidence of dramatic change during hominid 

 evolution. Of course, in fossil studies we are unable to determine brain 

 size as such; we are able to measure only the size of the braincase, the 

 endocranial capacity (often loosely called the cranial capacity). Although 

 much tissue and fluid intervene between the brain and the bony walls of 

 the cranial vault, there is obviously a relationship between the size and 

 shape of the two, variable though it may be. Following normal development, 

 big brains lie in big cranial vaults and small brains in small vaults. 



In selecting size as my yardstick of change in gross encephalic mor- 

 phology, I was, of course, aware of the work of numerous investigators who 

 have addressed themselves to other external morphological features, (e.g. 

 Le Gros Clark, Cooper, and Zuckerman 1936; Edinger 1948; Connolly 

 1950; Simon 1965; Bauchot and Stephan 1967). Such features have included 

 the lobes and areas of the cerebrum, the positions of certain key fissures, 

 the detailed pattern of convolutions and sulci— and what has been rather 

 inelegantly described by some as "the degree of sulcification" or "the degree 



