apes are confined to the more sheltered environment of forest and woodland. 

 It might be suggested that a ready wit, versatility, and inventiveness would 

 be necessary for survival in the challenging environment of open country, 

 with little natural protection from the carnivores and the elements. It is not 

 reading too much into this ecological fact to suggest that, to survive in open 

 country, the relatively defenseless Australopithecus would have had to de- 

 pend on his wits and resourcefulness to a far greater extent than would an 

 ape in forested terrain. 



The argument from general bodily structure and function. The 

 basic list of structural requirements for implemental activity comprises: (a) 

 brains of sufficient quantity and quality; (b) a strong element of learned 

 rather than exclusively or mainly instinctual patterns of behavior; (c) stereo- 

 scopic vision; (d) a prehensile hand capable of some degree of precision in 

 gripping; and (e) freeing of the forelimbs for short or long periods, as in 

 sitting upright. 



These basic requirements are fulfilled in numerous middle and higher 

 Primates; so that the anatomical potential for implemental activities is found 

 in baboons, monkeys, gibbons, great apes, and man. 



Moreover, all the items on this list of features that we can confirm from 

 the fossil record are present in Australopithecus. 



The arguments from specific anatomical and functional features 

 of Australopithecus. The teeth of Australopithecus. All of the australo- 

 pithecines differ from the pongids or apes in possessing relatively small 

 canine teeth that do not project to any appreciable extent beyond the plane 

 of the occlusal surfaces of the adjacent teeth (Robinson 1956; Tobias 1967a). 

 The absence of large canines strongly suggests that Australopithecus must 

 have used alternative mechanisms— manual and implemental— for solving 

 those sorts of problems for which apes use their large canines. 



The brain behind the hands. Although the mean capacity of the brain- 

 case of Australopithecus is very similar to that of the gorilla, we have enough 

 of the skeleton of the ape-man to indicate that his body weight was probably 

 far less than that of the gorilla. In other words, his estimated brain/body 

 weight ratio, or relative brain size, was higher than that of the biggest- 

 brained species of the living great apes. Then, too, the external configura- 

 tion of the brain of Australopithecus shows a number of manlike features. 

 It would seem likely that a brain that is more hominized in size and shape 



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