594 THE POPULAR SCIENCE MONTHLY 
THE PALEONTOLOGIC RECORD 
THE BIRTHPLACE OF MAN 
By Prorgssor 8S. W. WILLISTON 
THE UNIVERSITY OF CHICAGO 
ARIOUS writers, from Le Conte to Smith Woodward, have spoken 
of critical or rhythmical periods in evolution, periods when evo- 
lutionary forces have acted more vigorously than at others, with inter- 
vals of relative quiescence. What these forces are and have been we 
are not yet sure, whether extrinsic, that is, environmental or Lamarck- 
ian, or intrinsic, that is, orthogenetic, teleological or what not. Per- 
haps we shall sometime be more certain of the basal causes of evo- 
lution, for the paleontologist at least is not satisfied with the crass 
ignorance of our Weismannian friends who impute the beginning of all 
things to mere chance. Perhaps when we do know these fundamental 
causes we shall understand better why evolution has been rhythmical, 
if such was really the case, as some of us believe with Woodward. 
But, whether there have been internal forces which have had 
chiefly to do with the rhythm of evolution, or whether such critical 
periods in the evolution of organic life have been due solely to the 
larger cosmic forces, I think we shall all admit that there have been 
critical places of organic evolution, places upon the earth where evolu- 
tion has advanced with more rapid pace than in others, places per- 
haps where environmental conditions have conspired to hasten the de- 
velopment of life, or of particular groups, classes or kingdoms of life. 
Such a critical period, at least for the higher organisms, it seems to 
me, was the early Pliocene; such a critical place was central Asia; and 
both together resulted in the birth of man. 
It is a curious fact that nearly all our domestic animals had their 
origin in Asia. It is also a curious fact that the domestic animals are, 
almost without exception, the crowning ends of their respective lines 
of descent, the most highly specialized of their kinds. The genus Bos, 
the most highly developed of the even-toed ungulates began, to the 
best of our present knowledge, in the Lower Pliocene of India. And 
its four distinctive types likewise first appeared there: the Bubalus 
group, including the domestic buffalo of India, and its untamable kin 
of Africa; the group that is represented by the domesticated humped 
oxen of India and their wild relatives of Africa; the bison strain which 
spread in Pleistocene times almost to the remote corners of the earth; 
