Krantz has recently stressed the intimate relationship hetween brain 

 development and hunting. Leaving aside desultory hunting activities, such 

 as those that Australopithecus may have indulged in, Krantz concentrates 

 his attention on what he calls persistence hunting, which he describes as "a 

 uniquely human technique which is known to have been practiced recently 

 by some primitive peoples." As examples, he cites the Tarahumara of Mex- 

 ico, the Shoshonean Indians, and the Kalahari Bushmen. "In all of these 

 cases of persistence hunting, the game is finally taken primarily because the 

 hunter has been able to persist in the chase for as long as one or two days" 

 (Krantz 1968, p. 450). Clearly, a most important requirement for persistence 

 hunting, and one that is directly relevant to the development of the brain, 

 is "the ability to keep the task constantly in mind for several days and to 

 anticipate the results well into the future." 



He cites Rensch and Altevogt (1955) as showing that memory is directly 

 related to brain size, at least in their comparisons between different species 

 of animals. In all cases, Rensch and his co-workers concluded, the species 

 with the larger mean brain size proved to have the greater memory. Dob- 

 zhansky summarized their experiments in English and stated: "Rensch 

 concludes that the memory retention is about proportional to the brain 

 size in the animals experimented with by himself and his colleagues" 

 (Dobzhansky 1962, p. 201). Krantz comments: 



Judging from Rensch's observations, the increase of some 500 c.c. of endocranial 

 volume in Homo erectus [as compared with Australopithecus] must certainly 

 represent a tremendous increase in his memory. A brain at least % the size of 

 modern man's brain should have permitted H. erectus to engage in persistence 

 hunting in a manner approaching that observed in recent man. 



The idea of persistence hunting permits the following hypothesis as to the 

 selective forces that brought about the transformation from Australopithecus to 

 Homo: small steps in the enlargement of the Australopithecus brain would have 

 been of selective advantage mainly by increasing the time and distance that the 

 possessor would be able to pursue his mobile food supply. Considering the young, 

 injured, and aged as well as normal adults of all species of potential food available 

 to our ancestors, there was a continuous gradation in pursuit times necessary to 

 bring down game. At first, Australopithecus could run down only those animals 

 most quickly exhausted, and must have been in keen competition with many other 

 carnivores. As the reward in food for successful pursuit of game tended, on the 

 average, to go to those individuals with the greater mental time spans, selective 

 pressure would favour larger brains with better memories. [Krantz 1968, pp. 



45°-5'] 



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