180 NATURAL SELECTION VIL 
an advance in mind rather than by a change in body. If, 
therefore, we are of opinion that he was not really man till 
these higher faculties were fully developed, we may fairly 
assert that there were many originally distinct races of men ; 
while, if we think that a being closely resembling us in form 
and structure, but with mental faculties scarcely raised above 
the brute, must still be considered to have been human, we 
are fully entitled to maintain the common origin of all man- 
kind. 
The Bearing of these Views on the Antiquity of Man 
These considerations, it will be seen, enable us to place the 
origin of man at a much more remote geological epoch than 
has yet been thought possible. He may even have lived in 
the Miocene or Eocene period, when not a single other 
mammal was identical in form with any existing species. 
For, in the long series of ages during which these primeval 
animals were being slowly changed into the species which now 
inhabit the earth, the power which acted to modify them 
would only affect the mental organisation of man. His brain 
alone would have increased in size and complexity, and his 
cranium have undergone corresponding changes of form, while 
the whole structure of lower animals was being changed. 
This will enable us to understand how the fossil crania of 
Denise and Engis agree so closely with existing forms, al- 
though they undoubtedly existed in company with large 
mammalia now extinct. The Neanderthal skull may be a 
specimen of one of the lowest races then existing, just as the 
Australians are the lowest of our modern epoch. We have 
no reason to suppose that mind and brain and skull modifica- 
tion could go on quicker than that of the other parts of the 
organisation ; and we must therefore look back very far in 
the past to find man in that early condition in which his 
mind was not sufficiently developed, to remove his body from 
the modifying influence of external conditions and the cumu- 
lative action of natural selection. I believe, therefore, that 
there is no d@ priori reason against our finding the remains of 
man or his works in the tertiary deposits. The absence of 
all such remains in the European beds of this age has little 
weight, because, as we go farther back in time, it is natural 
