n their
differences of color. This color pigment is a protection against sunlight
and consequently varies with the intensity of the sunlight. Thus in Africa
we find the blackest men in the fierce sunlight of the desert, red pygmies
in the forest, and yellow Bushmen on the cooler southern plateau.

Next to the color, the hair is the most distinguishing characteristic of
the Negro, but the two characteristics do not vary with each other. Some
of the blackest of the Negroes have curly rather than woolly hair, while
the crispest, most closely curled hair is found among the yellow
Hottentots and Bushmen. The difference between the hair of the lighter and
darker races is a difference of degree, not of kind, and can be easily
measured. If the hair follicles of a China-man, a European, and a Negro
are cut across transversely, it will be found that the diameter of the
first is 100 by 77 to 85, the second 100 by 62 to 72, while that of the
Negro is 100 by 40 to 60. This elliptical form of the Negro's hair causes
it to curl more or less tightly.

There have been repeated efforts to discover, by measurements of various
kinds, further and more decisive differences which would serve as really
scientific determinants of race. Gradually these efforts have been given
up. To-day we realize that there are no hard and fast racial types among
men. Race is a dynamic and not a static conception, and the typical races
are continually changing and developing, amalgamating and differentiating.
In this little book, then, we are studying the history of the darker part
of the human family, which is separated from the rest of mankind by no
absolute physical line, but which nevertheless forms, as a mass, a social
group distinct in history, appearance, and to some extent in spiritual
gift.

We cannot study Africa without, however, noting some of the other races
concerned in its history, particularly the Asiatic Semites. The
intercourse of Africa with Arabia and other parts of Asia has been so
close and long-continued that it is impossible to-day to disentangle the
blood relationships. Negro blood certainly appears in strong strain among
the Semites, and the obvious mulatto groups in Africa, arising from
ancient and modern mingling of Semite and Negro, has given rise to the
term "Hamite," under cover of which millions of Negroids have been
characteristically transferred to the "white" race by some eager
scientists.

The earliest Semites came to Afr