highland people of Thibet, among the Garras on the
Hindoo-Chinese frontier, among the Baigas in Godwana, the Nairs in the
southern extremity of India; it is said to be found also among the
Eskimos and Aleutians. Heredity is determined in the only way
possible,--after the mother: the children belong to her. The husbands of
a woman are usually brothers. When the elder brother marries, the other
brothers likewise become the husbands of the woman; the woman, however,
preserves the right to take other men besides. Conversely, the men also
are said to have the right of taking a second, third, fourth, or more
wives. To what circumstances polyandry owes its origin is not yet clear.
Seeing that the polyandrous nations, without exception, live either on
high mountain regions, or in the cold zone, polyandry probably owes its
existence to a phenomenon that Tarnowsky comments on.[22] He learned
from reliable travelers that a long sojourn at high elevations lowers
the sensuous pleasures, and weakens erection, both of which return with
new vigor by re-descension to lower altitudes. This lowering of the
sexual powers, Tarnowsky is of the opinion, might partly account for the
comparative slight increase of population on highland regions; and he is
of the opinion that, when the debility is transmitted, it may become a
source of degeneration that operates upon the perversity of the sexual
sense.

We may also add that a protracted domicile, together with the habits of
life contracted on very high or cold regions, may have for a further
result that polyandry lays no excessive demands upon a woman. The women
themselves are correspondingly affected in their nature. That they are
so is rendered probable by the circumstance that, among the Eskimo
girls, menstruation sets in only with the nineteenth year, whereas in
the warm zones it sets in as early as the tenth or eleventh, and in the
temperate latitudes between the fourteenth and the sixteenth year. In
view of the fact that warm climates, as universally recognized, exercise
a strongly stimulating influence upon the sexual instinct,--whence
polygamy finds its widest diffusion in warm countries--it is quite
likely that cold regions--to which high mountains and plateaus belong,
and where the thinner air may also contribute its share--may exercise
materially a restringent effect upon the sexual instinct. It must,
moreover, be noted that experience shows conception occurs rarer with
women who coh