brain in total mass must be replaced by more molecular appreciation of 

 the range of structural and behavior changes for different extant primate 

 species" (1968a, p. 165). 



It may well be that he is correct. If so, our study of endocranial ca- 

 pacities will be simply a study of changing morphologies, but not of chang- 

 ing cerebral functions, nor of changing behavior patterns. 



Interrelations of parameters 



That the various sets of data are related, and causally related, is un- 

 doubted. Increase in brain size must have occurred together with increasing 

 complexity of internal organization; increasing complexity of organization 

 must have had its counterpart in changing functional patterns; these in 

 turn permitted the emergence of changing patterns of behavior, as mani- 

 fested, for instance, in material culture and hunting. 



We know rather a lot about both ends of this causal chain: the size and 

 shape of brain or endocast at one end; the cultural life and hunting be- 

 havior at the other end. It is the intermediate links in the chain that have 

 eluded us up to now and that are becoming the object of serious investiga- 

 tion. The uncertainty of the intermediate steps by no means invalidates 

 the study of the 2 termini of the causal chain. 



In this volume I have thus far concentrated on one end of the chain, 

 the endocasts. More particularly, I have concentrated on the total size as 

 the most reliable parameter of the brain's or endocast's morphology. I have 

 deliberately refrained from entering into a discussion of such features as 

 the fissuration of the brain, because of the vagueness and uncertainty shroud- 

 ing both the recognition and the interpretation of such fissural impressions 

 on the endocranium and on the surface of the endocast. From his own 

 studies and those that he made with Bailey, von Bonin (1963, p. 76) was 

 driven to say forthrightly: "We consider the time and effort spent on the 

 fissures of the fossil brains as largely wasted." 



This review of the endocranial capacities of fossil hominids has left 

 no doubt that a trend toward increasing brain size occurred from the earliest 

 stages of hominid evolution reviewed here * to at least the penultimate 

 stage, that of Upper Pleistocene man. 



Not only is the trend manifest; one can go further and say that it is 

 the most strikingly sustained trend shown in the fossil record and, hence, 



* We have no data on the cranial capacity of the Mio-Pliocene creatine, Ramapithecus, which, 

 because of its teeth and jaws, is generally regarded today as a member of the Hominidae. 



>J( .14 



