rkshop before they can be profitably
understood as working mechanisms, so the physical evolution of mankind
must first be made intelligible before it is possible to prosecute
successfully the studies dealing with the psychology, social relations,
and higher conceptions that seem at first to be the exclusive properties
of our species.

The problems of physical evolution of man and of men fall into two groups.
Those of the first deal with the origin of the human species as a unit,
and its comparative relation to lower organisms, while those of the second
part are concerned with the further evolution of human races that have
come to be different in certain details of structure since the human type
as such arose. In the first part, all men will be assumed to be alike and
the members of a homogeneous species whose fundamental attributes are to
be compared with those of other animals; only afterwards will attention be
directed to the differences, previously ignored, that divide human beings
into well-marked varieties. It must be evident even at this point that the
mode of evolution demonstrated by the first investigation will be likely
to bear some close relation to the methods by which human races have
evolved to their present diverse anatomical situations.

* * * * *

The foregoing classification of the problems concerned with the nature and
origin of the human species renders it possible to restrict the immediate
inquiry to a definite and precise question. It is this: does the evidence
relating to the physical characteristics of our species prove that man is
the product of a supernatural act of creation, or does it show that man's
place in nature has been reached by a gradual process of natural
evolution? In order to obtain an equally precise and definite answer to
this question, referring to the particular case of most concern to us, it
is obvious that the method to be employed is the one which has given us an
understanding of organic evolution as an all-inclusive natural process.
The data must be verified, related, and classified, so that their meaning
may be concisely stated in the form of scientific principles. What are the
facts of human structure, comparatively treated? How does the human body
develop? Does palaeontology throw any light on the antiquity of man? Do the
rules of nature's order control the lives of men? Our course is now clear;
we shall take up serially the anatomy, embry