(especially the development of the structural basis for the bipedal gait) was 

 an evolutionary response to the emergence of tool-using and hunting, these 

 3 trait-complexes being linked by a triplet of positive feedbacks, 



Bielicki's conception represents an ingenious attempt to develop the 

 notion of feedback and to provide a mechanism by which the very potent 

 set of evolutionary pressures generated by the development of culture can 

 play its part. It is clear that culture has come to play a dominant role in 

 hominid evolution. Some ten years ago, in my presidential address to 

 Section E of the South African Association for the Advancement of Science, 

 I tried to develop this concept to explain rapid human evolution. Then, I 

 suggested that when Cultural Selection and Natural Selection pull in the 

 same direction, evolutionary change would be most rapid (Tobias 1961, 



PP- 33-36). 



The notion was developed originally to explain steatopygia in the 

 Bushmen— for this seemed to provide an excellent example of a selectively 

 advantageous feature, the intensity of selection of which has been heightened 

 by sexual or cultural pressures. The short size of the Bushmen was another 

 phenotypic trait that seemed to be favored both for survival and by cultural 

 preferences. The stronger the cultural pressures, the more drastic would 

 be the cultural selection of certain qualities deemed desirable. If these 

 qualities also assist the survival of the population, then both natural and 

 cultural selection would operate in the same direction, and human evolu- 

 tion would proceed at a dramatically rapid tempo. The relevance of this 

 example from micro-evolutionary change for the macro-evolutionary di- 

 mension of which Bielicki speaks is that it was suggested by me not that 

 Cultural Selection ousted or supplanted Natural Selection, but that it com- 

 plemented Natural Selection.* 



Now, it seems to me that, excellent as is the hypothesis proposed by 

 Bielicki, it errs by not allocating an adequate place to Natural Selection. 



* Eiseley has drawn attention to the oft-overlooked Darwin-Wallace controversy on the mechanism 

 of human evolution. While Darwin had adhered rigidly to Natural Selection as an adequate 

 explanation of the rise of man and his brain, Wallace had realized that "some more rapid process 

 of evolution than that envisaged in the Darwinian philosophy must have been at work in the pro- 

 duction of man" (Eiseley 1956, p. 6g). Seven years before The Descent of Man, Wallace had 

 asserted that evolution in cultured man was largely mental, and that even racial differences 

 were essentially survivals from the time when man was a still cultureless animal. However, he 

 did not take the further step of postulating that this very culture had come to dominate selective 

 processes in man. Instead, because he could envisage no other force to account for the rapid rise 

 of the human brain, Wallace invoked a directive spiritual force that could not be accounted for 

 in purely mechanistic teims. 



147 & 



