EVOLUTION, GENETICS, ANTHROPOLOGY — MOURANT 503 



tions were man's origin and his place in nature; in 1862 Huxley 

 published Mail's Place in Nature and in 1871 Darwin's Descent of 

 Man appeared. 



These two men, friends and close colleagues though they were, dif- 

 fered considerably in outlook, and this is instanced in particular by 

 their views upon the nature of inheritable variations in living beings 

 in general. These views had a particular bearing upon the nature 

 of interspecific differences and upon the question, perpetually stressed 

 by Huxley, of whether natural selection alone, acting upon a single 

 species, could bring about a separation into two mutually infertile 

 species. 



Both men were almost certainly completely unaware of the con- 

 temporary work of Mendel who showed that, in the cases which he 

 investigated, inheritable differences were finite and discontinuous. 

 Darwin, though of course aware of isolated examples of discontinuous 

 variation, appears, to the end of his life, to have regarded selection as 

 operating essentially upon a continuous series of quantitative 

 variations. 



Huxley seems to have been much more actively interested than 

 Darwin in the question of how hereditary variation took place, and 

 more fully conscious of tJie existing lack of knowledge of these 

 mechanisms, and of the need for further research. In 1861, four years 

 before the publication of Mendel's classical work, he wrote to Sir 

 Joseph Hooker asking "Why does not somebody go to work experi- 

 mentally, and get at the law of variation for some one species of 

 plant?" — a task upon which Mendel was probably even then at work. 

 It would be possible to point to a number of statements by Huxley 

 which show an intuitive anticipation of modern genetical theory, of 

 which two may be quoted : 



the important fact . . . that the tendency to vary, in a given organism, may have 

 nothing to do with the external conditions to which the individual organism is 

 exposed, but may depend wholly upon internal conditions. (Huxley, 1869.) 

 Hence it is conceivable, and indeed probable, that every part of the adult con- 

 tains molecules, derived both from the male and from the female parent. . . . 

 The primitive male and female molecules may . . . mould the assimilated nu- 

 triment, each according to its own type, into innumerable new molecules. (Hux- 

 ley, 1878.) 



It would, however, be wrong to assume that Huxley anticipated in 

 any complete sense the modern genetical view that the heritable basis 

 of all variation is discontinuous. Certainly in the science of physical 

 anthropology, which Huxley did so much to foster, and which was 

 growing so rapidly at this time, the stress was on the precise measure- 

 ment of parameters regarded as forming continuous series. 



In the hundred years which followed Ketzius's introduction of 

 the cranial index, the subject matter of physical anthropology con- 



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