EVENING DISCOURSES. 787 
loss by the mouth of its function as a weapon. Increase of intelligence removed 
the necessity for so much brute force, and the face then became reduced in 
size, while the familiar weakness of the jaws of man was the result. ; 
Finally, Hoanthropus may be considered from another point of view to 
which I have directed attention—the frequent parallelism between the life- 
history of a modern individual animal and the geological history of the race to 
which it belongs. If we compare the Piltdown skull with that of the next 
oldest fossil man—the Neanderthal or Mousterian type—the most striking 
difference in the brain-case is the presence in this later man of strong, bony 
brow-ridges like those of existing apes. It will also be noticed that the brain- 
case is much larger and the jaws are now human, though the face remains 
relatively well-developed. The differences in the brain-case between the earlier 
Piltdown and the later Neanderthal skulls thus correspond with those observ- 
able between the skull of a very young modern ape and that of the full-grown 
individual of the same species. The brow-ridges are, in fact, bony excrescences 
acquired during life. Now, on the principle of parallelism I have just men- 
tioned, the ancestral Middle Tertiary apes (which we have not yet found) may 
be supposed to have had gently-rounded ovoid skulls without brow-ridges. In 
that case the Piltdown skull is much nearer in shape to that of its ancestor 
than the later Neanderthal skull. Hence, the Neanderthal race must be 
regarded as a degenerate offshoot of early man which has become extinct, and 
Piltdown man, or some close relative, may be on the direct line of descent of 
ourselves. 
We see, therefore, from the study of the links in the chain of life found 
among extinct animals, that man, so far as his physical structure is concerned, 
is the natural outcome of the course of evolution we observe. It was not 
until the last phase in the geological history of the backboned animals that 
efficiency of the brain became of any real importance. The reptiles for long 
ages occupied every sphere of life and grew to astonishing proportions with 
only the most insignificant nervous centres. As soon as the warm-blooded 
mammals appeared, increase of brain-power became the essential factor in 
success in the struggle for existence. In most cases it merely kept pace with 
other changes in the body and aided in the general efficiency. In some cases, 
where these animals of the highest grade continued to live in the forest (which 
we have every reason to believe was the original home of all), the development 
of the brain was the only real change that occurred in their structure. In one 
forest-dwelling race the momentum of this development resulted in such over- 
growth that the brain eventually dominated the body, and the inevitable 
outcome was the primitive human frame. 
3E2 
