f branches arising from a common limb. This
is the relation that we have earlier found to be a universal one
throughout the animal kingdom, and science believes that it indicates
everywhere an evolutionary history--an actual development along different
lines of descent of forms which have a common starting-point and ancestry.

The second principle is perhaps even more significant: when we review the
many races from the Caucasian to the dwarf Negrito, we traverse a downward
path which will bring us inevitably to the higher apes. In our survey of
human races, we have passed from the Caucasian, with the largest brain and
cranium and with straight jaws well underneath the brain-case, to the
pygmy with a relatively small brain, with huge projecting jaws and with
prominent ridges over the eyes; one step more along that path would bring
us to the gorilla or the chimpanzee. The array of lower primates, from the
lemur to the gorilla, gives a series of forms exhibiting a progressive
advance in respect to the size of the brain and cranium, and a gradual
retreat of the jaws to a position underneath the cranium; and one step
further brings us to man. In a word, these two lines join--in fact, they
are directly continuous. There is a far smaller difference between the
lowest man and the highest ape than we have been accustomed to suppose.

Thus in general terms, it can justly be said that process of evolution
which developed the first man from its ape-man progenitor seems to have
continued during subsequent ages. Spreading out in diverging lines of
evolutionary descent no less clearly than they have in geographical
respects, certain races have far surpassed their fellows of a lower order,
which, like the brute pygmy, remain nearer the common structural form from
which all men have sprung.

VI

THE MENTAL EVOLUTION OF MAN

The problems dealing with the make-up of the human mind and with the
evidences of mental evolution bring the student to matters of more vivid
human interest. Mental phenomena are so complex and intricate that it is
well-nigh impossible to analyze their history without a knowledge of the
principles derived from the broad study of evolution as a general
doctrine, where human prejudice is not so large a factor and where his
perspective is less affected by the proximity of the observer to his
facts. For these and other reasons the foregoing treatment of human
evolution has been confined to the purely structur