IX LIMITS OF NATURAL SELECTION IN MAN 197 
the accumulation of variations from a hairy ancestor. The 
evidence all goes to show that such variations could not have 
been useful, but must, on the contrary, have been to some 
extent hurtful. If even, owing to an unknown correlation 
with other hurtful qualities, it had been abolished in the 
ancestral tropical man, we cannot conceive that, as man 
spread into colder climates, it should not have returned under 
the powerful influence of reversion to such a long persistent 
ancestral type. But the very foundation of such a supposi- 
tion as this is untenable, for we cannot suppose that a 
character which, like hairiness, exists throughout the whole 
of the mammalia, can have become, in one form only, so 
constantly correlated with an injurious character as to lead to 
its permanent suppression—a suppression so complete and 
effectual that it never, or scarcely ever, reappears in mongrels 
of the most widely different races of man. 
Two characters could hardly be wider apart than the size 
and development of man’s brain and the distribution of hair 
upon the surface of his body, yet they both lead us to the 
same conclusion—that some other power than natural selec- 
tion has been engaged in his production. 
Feet and Hands of Man, considered as Difficulties on 
the Theory of Natural Selection 
There are a few other physical characteristics of man that 
may just be mentioned as offering similar difficulties, though 
I do not attach the same importance to them as to those I 
have already dwelt on. The specialisation and perfection of 
the hands and feet of man seems difficult to account for. 
Throughout the whole of the quadrumana the foot is pre- 
hensile, and a very rigid selection must therefore have been 
needed to bring about that arrangement of the bones and 
muscles which has converted the thumb into a great toe, so 
completely, that the power of opposability is totally lost in 
every race, whatever some travellers may vaguely assert to 
the contrary. It is difficult to see why the prehensile power 
should have been taken away. It must certainly have been 
useful in climbing, and the case of the baboons shows that it 
is quite compatible with terrestrial locomotion. Tt may not 
be compatible with perfectly easy erect locomotion ; but, then, 
