143]

In these few lines Darwin clearly indicated the way in which we were
to conceive our ancestral series within the vertebrates. It is fully
confirmed by all the arguments of comparative anatomy and embryology,
of palaeontology and physiology; and all the research of the
subsequent forty years have gone to establish it. The deep interest in
geology which Darwin maintained throughout his life and his complete
knowledge of palaeontology enabled him to grasp the fundamental
importance of the palaeontological record more clearly than
anthropologists and zoologists usually do.

There has been much debate in subsequent decades whether Darwin
himself maintained that man was descended from the ape, and many
writers have sought to deny it. But the lines I have quoted _verbatim_
from the conclusion of the sixth chapter of the _Descent of Man_
(1871) leave no doubt that he was as firmly convinced of it as was his
great precursor Jean Lamarck in 1809. Moreover, Darwin adds, with
particular explicitness, in the "general summary and conclusion"
(chap. xxi.) of that standard work:[144]

"By considering the embryological structure of man--the homologies
which he presents with the lower animals,--the rudiments which he
retains,--and the reversions to which he is liable, we can partly
recall in imagination the former condition of our early progenitors;
and can approximately place them in their proper place in the
zoological series. We thus learn that man is descended from a hairy,
tailed quadruped, probably arboreal in its habits, and an inhabitant
of the Old World. This creature, if its whole structure had been
examined by a naturalist, would have been classed amongst the
Quadrumana, as surely as the still more ancient progenitor of the Old
and New World monkeys."

These clear and definite lines leave no doubt that Darwin--so critical
and cautious in regard to important conclusions--was quite as firmly
convinced of the descent of man from the apes (the Catarrhinae, in
particular) as Lamarck was in 1809 and Huxley in 1863.

It is to be noted particularly that, in these and other observations
on the subject, Darwin decidedly assumes the monophyletic origin of
the mammals, including man. It is my own conviction that this is of
the greatest importance. A number of difficult questions in regard to
the development of man, in respect of anatomy, physiology, psychology,
and embryology, are easily settled if we do not merely extend our