27 
stance would then have arisen, actually forcing on the per- 
petuation of this abnormal variety ; and its isolation from the 
rest of men would, in a few generations, have quite removed 
from its own consciousness any feeling of peculiarity. Ihis 
family, thrown out thus in the forefront of man’s geographical 
distribution over Africa, would of course increase and multiply 
after its own sort. 
51. (II.) Tribal Quarrelsomeness or Persecution would 
have been equally calculated to produce the same results. 
No one who is familiar with human nature can object to the 
probability of our supposing that family disturbances would 
take place among the early tribes of mankind— disturbances 
in which strife and violence might force out the weaker party, 
and turn it adrift upon the world. The conduct of Hagar 
and Ishmael is a good illustration of this. In the history ot 
primitive settlements there can be little doubt that many such 
instances of forced separation must have occurred— separa- 
tions by which families, small at first, subsequently grew into 
tribes, and, perhaps, distinct varieties of mankind. iSlow it 
any one cause could arise better calculated than another to 
produce such quarrels and persecutions, would it not be found 
in those personal antipathies and proud jealousies which would 
inevitably spring up in the midst of a rude and semi-civilized 
family, where one portion of it would be as abnormal and 
repulsive to the rest as these black- skinned, woolly-headed 
members ? A hundred different contingencies might be 
named as having been likely to bring about this result. 
52. (III.) If either of these causes be considered impossible 
or improbable, there remains another way of accounting for 
the fact in question, viz., Disease. . 
I have already observed that, in the regions now. occupied 
by the Negroes, there exists a species of malaria which, while 
it is perfectly innocuous to their constitution, is generally fatal 
to others. On the supposition, therefore, that the congenital 
variety, thus physiologically fitted to resist the. malaria, ap- 
peared among the first batch of early settlers in those 
ticular regions, nothing would be more consistent with the 
laws of nature than that this exceptional constitution should 
gradually have become increased and perpetuated, while the 
original stock became obliterated. _ . 
53. We have a curious and valuable illustration of this idea 
furnished by Professor Huxley's little book previously quoted,* 
in which he gives an account of the perpetuation of a black 
race of swine in America, simply induced by the extermination 
of the white portion of the flock through disease. 
* P. 130. 
