Painting by Charles B. Knight, from American Museum of Natural History 



HAIRY MAMMOTH 



Scientists could not "prove" their guesses about the characteristics of this animal, or 

 even about its existence some 100,000 years ago, but for the rare chance that some 

 of these giants had "been caught in the swamps and had been preserved in the frozen 

 state — and were then dug up by men who had the wit to piece the story together 



ancestry, on the basis of resemblance (see page 36). That is, we see and 

 handle only individuals, but if several are enough alike for us to consider them 

 of the "same kind" or species, we call them by a common name and ta\e for 

 granted a common ancestry. 



Now, according to the older idea of Linnaeus and others, each animal 

 species and plant species is distinct from all the others, and came into existence 

 independently. It "exists" in the same sense as a particular individual exists. 

 But arranging plants and animals according to degrees of resemblance leads to 

 a grouping of species into genera, of genera into families, of families into orders, 

 and so on into larger and larger assemblages (see page 38). 



The characteristic "branching- tree arrangement" of all the kinds of living 

 things recalls the arrangement of individuals in a "family tree", where the 

 relationships are known. This similarity naturally suggests that different 

 classes and orders and genera of plants and animals are related to each other as 

 are members of a species, namely, in the sense of having descended from com- 

 mon ancestors (see frontispiece). Indeed, Linnaeus, in the first edition of his 

 great work, treated the "genus" as if it represented the original ancestor and 

 the species as mere variations on the theme. 



456 



