The surmounting of a peak 



Another provocative factor that arises on contemplation of the data on 

 increasing capacity is that the selective pressures that led to the emergence 

 and further development of the brain size of Homo erectus did not lapse. 

 They did not lead to a graphical plateau in the heyday of H. erectus. The 

 trend of rising mean endocranial capacities during the earlier stages of 

 Pleistocene hominization undoubtedly continued into the Upper Pleisto- 

 cene; it is reflected by a further increase in brain size in the early stages of 

 H. sapiens. 



Then the selective pressures seem to have relaxed somewhat, a few 

 score thousand years ago (von Bonin 1034, Weidenreich 1946). Skulls of 

 that date from Neandertal men of Europe, and also those of fossil men 

 from Africa, had bigger braincases on the average than those of their pres- 

 ent-day descendants. The graph of rising brain size flattened out to a 

 plateau and then began to drop somewhat. 



Although no attempt will be made here to review the evidence for 

 this latest phase of hominization, some examples of Upper Pleistocene endo- 

 cranial capacities from Africa may be quoted: Hopefield (Saldanha) ca. 1225 

 ex.; Broken Hill 1280 c.c; Gamble's Cave 1470 ex. and 1530 c.c; Naivasha 

 1453 c.c; Taforalt 1376 c.c. and 1647 c.c; Boskop 1650 c.c; Fish Hoek 

 1550 c.c; Matjes River crania 1230 to 1660 c.c; and Asselar 1520 c.c. Most 

 of the crania cited have high capacities, probably well above the mean for 

 most present-day populations. This underlines the general statement made 

 earlier that modern man— whether in Africa or Europe— would seem to have 

 somewhat lower mean brain sizes than his forebears of the early Upper 

 Pleistocene. 



It seems that the trend toward increased brain size, which marked the 

 first 2 or 3 million years of human evolution, had spent itself— and had 

 done so as recently as the late Pleistocene. The wave of brain expansion 

 had passed its peak. Some of our Stone Age men carried the twin processes 

 of reduction of teeth and jaws, on the one hand, and expansion of brain, 

 on the other, so far that they seem to represent an ancient foreshadowing of 

 the popular idea of the man of the future. The matter has been most vividly 

 portrayed by Loren Eiseley, Benjamin Franklin Professor at the University 

 of Pennsylvania. In one of the essays in his delightful florilegium of anthro- 

 pological sketches. The Immense journey, he writes: 



One . . . skull lies in the lockers of a great metropolitan museum. It is labelled 

 simply: Strandloper, South Africa. I have never looked longer into any human 



5^ too 



