264 ANXIJAL REPORT SMITHSONIAN INSTITUTION, 194 



animals in any region. There is a constant ebb and flow within 

 the fauna itself, due to local and temporaiy influences, a swing of 

 the pendulum about a mean, the "balance of life" which is never 

 quite struck. But there is also a faunal drift, revealed in the story 

 of the rocks or in any long vista of faunal history, and this is due 

 to great secular changes, to geologic influences, to modifications of 

 climate, to the insurgence of the forces of life. 



Wliere man's interference is temporary and casual it may be 

 compared to the internal faunal tide, which is of little moment in 

 the long run ; but where his interference is persistent in any direction 

 it must be reckoned as sharing with the great secular forces of 

 nature in propelling a fauna upon a path along which there is no 

 return. 



Such is the remarkable conclusion to which the long view of 

 man's place as a natural agent brings us — ^that he has set in motion 

 forces which, in our era and mainly in the last 300 years, have 

 wrought faunal changes which can be compared only with the great 

 secular changes of world evolution. And when the ridiculously 

 short span of his interference is contrasted with the slowness of 

 natural processes, the probability forces itself upon us that in a 

 few more thousand years of man's inheritance of the earth the old 

 order of nature will be superseded in the faunas of the world by a 

 new order of mankind. 



MAN IN BVOLUTIONAHY PERSPECTIVE 



Having thus assigned to man dominance amongst the forces which 

 determine faunal assemblages, let me now endeavor to put him in 

 his place in the long perspective of life and evolution. 



Temporarily his past is insignificant, how insignificant it is almost 

 impossible to realize. But let us picture the unimaginable space 

 of time since life began as a 12-hour day, beginning with the first 

 living molecules in an early world at midnight and reaching a climax, 

 as we should say, at the high noon of evolutionary attainment — 

 ourselves. These 12 hours will represent, according to the data I 

 have already referred to, roughly 1,200 million years, each hour 100 

 million years, each minute rather more than II/2 million years. Our 

 clock must be a 24-hour clock, for we can assume that life and evo- 

 lution will continue in the future (for the convenience of my dia- 

 gram, supported by the calculations of the physicists) say as long 

 as life has already existed. Then the long period of indeterminate 

 living things almost unrepresented by fossils would have existed 

 from zero till 7 o'clock; the Paleozoic period, when fishes and am- 

 phibia predominated, till about 10 o'clock; the Secondary period 

 with its predominant reptiles till about 11:15; and the great devel- 



