tors is indicated
by the fact that the Negro race has been decimated, wherever it has met
tuberculosis. "In the years 1803 and 1810 the British government
imported three or four thousand Negroes from Mozambique into Ceylon to
form into regiments, and of these in December, 1820, there were left
just 440, including the male descendants. All the rest had perished
mainly from tuberculosis, and in a country where the disease is not
nearly so prevalent as in England."[61] Archdall Reid has pointed
out[62] that the American, Polynesian and Australian aborigines, to whom
tuberculosis was unknown before the advent of Europeans, and who had
therefore never been selected against it, could not survive its advent:
they were killed by much smaller infections than would have injured a
European, whose stock has been purged by centuries of natural selection.

These racial histories are the most important evidence available to the
student of natural selection in man. The conclusion to be drawn from
them seems plain. Natural selection, which has in the past never had an
opportunity to act upon the Negro race through tuberculosis, is now
engaged in hastening, at a relatively rapid rate, the evolution of this
race toward immunity from death by tuberculosis. The evolution of the
white race on this line is, as the figures show, going on
simultaneously, but having begun centuries earlier, it is not now so
rapid. The weakest white stocks were cut off hundreds of years ago, in
Great Britain or Europe; those of the black race are only now going.
Despite all the efforts of medicine and sanitation, it is likely that
the Negro death-rate from phthisis will continue high for some years,
until what is left of the race will possess a degree of resistance, or
immunity, not much inferior to that of the whites among whom they live.
The blacks in North America now must be already more resistant than
their ancestors; the mulattoes descended of normal healthy unions should
be more resistant than the pure Negroes, although no statistics are
available on the point; but were a new immigration to take place from
Africa to-day, and the immigrants to be put into villages with their
Americanized brethren, the high death-rate would result.

While the Negroes were thus undergoing the radical surgery of natural
selection, what was happening to the aborigines of America? The answer
of history is unmistakable; they were meeting the same fate, in an even
more violent fo