ciated with the behavior; otherwise, evolution is impossible" (Holloway 

 1969a, p. 2). 



Again, Holloway joins issue with Le Gros Clark when the latter states: 



For it is not what animals do in their natural environment, but what they can do 

 under changing and adverse conditions, that will ultimately determine how they 

 will become adapted behaviourally, and finally physically, to new environments. 



. . . progressive evolutionary development surely depends on deliberate efforts 

 made by individual animals, and by the communities of which they are members, 

 to overcome adverse and difficult problems with which they are faced in order to 

 ensure the survival of the species. ... If a species by such strivings can manage 

 to survive for a sufficient length of time in surroundings for which it is not as yet 

 fully adapted in its physical make-up, then the opportunity is provided for the 

 gradual development by advantageous mutational variations of morphological 

 changes that adapt the species more perfectly to its ecological environment. [Le 

 Gros Clark 1967, pp. 121-22] 



In his review of Le Gros Clark's Man-Apes or Ape-Men? Holloway com- 

 ments, "This seems an unfortunate way to word the essential message: that 

 plasticity of behavior was important in evolution. Left as it is, the statement 

 is out of bounds with genetic and evolutionary theory" (Holloway 1968b, 

 p. 422). 



This kind of chicken-egg argument does not seem to be a particularly 

 fruitful controversy. I find greater potential value in an approach that 

 stresses the two-sidedness or reciprocity between genetico-structural bases 

 and behavioral expressions. This relationship, modern thinking would indi- 

 cate, is essentially a feedback one (Dobzhansky 1962, 1963; Bielicki 1964, 

 1965, 1969; Holloway 1967). 



To quote Washburn and Howell: 



Darwin and many workers after him stressed development of bipedal locomotion 

 as a factor in differentiating man from ape. This process freed the hands, made 

 possible the use and manufacture of tools, and led to reduction in the size of the 

 teeth and the facial skeleton. The australopithecines in general represent such a 

 stage in human evolution. [Washburn and Howell i960, p. 35] 



But they modify this view a page or two further on by commenting: 

 "Perhaps, as Darwin suggested, tool use is both the cause and effect of 

 hominid bipedalism, and the evolution of erect posture occurred simul- 

 taneously with the earliest use of tools" (ibid., p. 37). 



These views remind us that there must have been a subtle reciprocal 



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