BUTTERFLIES AND MOTHS AS EVIDENCE OF EVOLUTION
By Edward Bagnall Poulton
Hope Professor of Zoölogy in the University of Oxford
On the wings of butterflies “nature writes, as on a tablet, the story of the modifications of species. . . . As the laws of nature must be the same for all beings, the conclusions furnished by this group of insects must be applicable to the whole organic world.” (H. W. Bates.)
In spite of my title and my quotation from the great naturalist of the Amazon I must at the outset consider for a moment the evidence by which the belief in any scientific theory is justified. Why do we believe that the theory of the movements of the planets and satellites in our solar system is true? We believe it because by the light of this theory astronomers can predict the future, and we know from experience that their predictions will be verified. Farseeing people years ago made arrangements for observations on June 29, 1927, because they had been told by astronomers that on that day the moon would come between the sun and the earth, that its shadow would sweep across England from Southport to Hartlepool, and that every place in succession on that line would be, for about 25 seconds, buried in the darkness of total eclipse. And at the precise moment we saw, just as predicted, its sudden onset and swift passing away, while, in favored places where fortunately the astronomers had erected their instruments, the clouds cleared and
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