At any rate, it is gratifying to record that the slavish dependence on 

 brain size as a basis for interpreting behavior is no longer so evident. That 

 it is a morphological feature in its own riglit and worthy of study as such is 

 undoubted. But the extent to which inferences as to behavior may be based 

 upon it is very strictly limited. The attempt to look into the fossil brain 

 by comparative and analytical and deductive means, such as rather coura- 

 geous young palaeoneurologists like Jerison and Holloway are attempting, 

 is most salutary. They are rising to the challenge posed in the closing words 

 of von Bonin's little book, The Evolution of the Human Brain (1963), 

 where he stated: "To write an evolution of the mind from the point of the 

 view of the brain is not yet feasible. 



Reorganization during the evolution of the brain 



Several workers have recently stressed the major reorganization that 

 the internal structure of the brain must have undergone during evolution 

 to account for the differences encountered in living mammals and in 

 Primate series. Few people have done more in recent years than R. L. Hollo- 

 way Jr. to draw attention away from such traditional parameters as brain 

 weight, cortical area, and even from such newer dissection instruments as 

 are afforded by neuron density, neuron number, and glia/neuron ratios, 

 and toward a probe into the patterns of structural organization that dif- 

 ferentiate various living mammals and, especially, Primates (Holloway 1966, 

 1967, 1968a, 1969a, 1969b). Of course, he is not alone in this: von Bonin 

 (1963, p. 77) has reminded us that "mere size completely leaves out of ac- 

 count the inner structure of the brain, which may be different in different 

 forms and which may determine to a great extent what the brain can do." 



Holloway has pleaded powerfully that the most important and, be- 

 havioral ly, the most relevant internal changes during hominid brain evolu- 

 tion, including increase in brain size, are not the increased number of 

 neurons (pace Jerison), nor changes in numbers and ramifications of proc- 

 esses, nor in glia/neuron ratios. Instead, the changes of greatest import for 

 behavioral patterns are those involving reorganization of both cortical and 

 subcortical components of the brain. It is unnecessary here to review all 

 the evidence— comparative, experimental, and ontogenetic— bearing on such 

 reorganization: in any event, a good deal of the evidence has been drawn 

 together and summarized by Holloway (1968a). 



Holloway's view may be summed up as follows: "The growth or ex- 

 pansion of cranial capacity is not our primary problem in understanding 

 brain and behavioral evolution" (1970a, p. 309). Also: "Discussions of the 



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