LIMITS OF VARIATION IN THE SPECIES.
The folk-lore of all nations tells about giants and dwarfs, and up to a recent date sober writers were willing to accept some of these tales as founded on fact. Now, however, it is well ascertained that the limits of variation in the human species are much narrower than those of any species of domestic animal—the dog or the ox, for instance. It is a still later result of investigation that these variations are not characteristics of races or sub-species, but rather of tribes and localities.
Height and is especially true with regard to height and weight. Thus in South Africa we find the Bushmen, usually quoted as the smallest of the human family, having an average height of only 144 centimetres (56.7 inches), while adjacent to them are the Caffirs, of such unusual stature that the average of ten of them was 183 centimetres (72 inches), both tribes belonging to the Negro race. The same contrast reappears among the Malayans. The Asiatic Malays are quite short and feeble, their average height being 154 centimetres (6o.6 inches), while the Polynesian Malays of some of the Pacific Islands are among the largest of men, running up to the extraordinary average height of 193 • centimetres (76 inches). The Obongos of the Soudan and the Lapps of Northern Europe are scarcely, if at all, taller than the Bushmen. The Eskimos are also quite short, but it would be a hasty generalization to infer, with some writers, that the extreme cold of the high latitudes necessarily lowers the stature, as the nation of the white race which has the highest average stature is the Scandinavian ; whereas the Ved dahs of Ceylon, a wild tribe said to be of Aryan descent, are small and weak.
Height, weight, and muscular power can be developed within the limits of any race by favorable surroundings. During the Civil War in the United States measurements in these directions were taken in over a million subjects belonging to the white, the black, and the red races. The interesting result was obtained that residence on this conti nent—at least on the northern portion of it—tends to develop all the races in all these respects. The descendants in the second or third generation of European settlers are taller and heavier than the average Englishman, Frenchman, or German ; the recruits from the Mississippi Valley were taller and stronger than those from the coast ; but both were surpassed in these respects by the native race of the soil, the Iroquois Indians, some five hundred of whom were included in the comparison.
The tallest soldiers were from the States of Kentucky and Tennessee. They measured an average of 176 centimetres (69.3 inches), while the Iroquois braves reached to an average of 179 centimetres (70.3 inches).
All these statistics, it should be remarked, apply exclusively to the male sex. The female sex displays very much less variation. In the shortest and weakest races the females are physically equal to the males, and indeed often surpass them. On the other hand, where the stature of the males is decidedly beyond the normal the female departs little from it. Hence on measurements confined to the female sex alone the limits of the variation of the species in these respects are more circumscribed.
Epoch of attainment of the epoch of puberty and of that of completed growth are other points in the first rank of physiolog ical importance in which there is considerable variation. In general terms, it may be said that puberty arrives in the tropics about three years earlier than in high northern latitudes. That this difference is closely dependent on temperature seems proved by the fact that healthy children of parents from the temperate zones ripen more quickly in the tropics, without regard to race, while the reverse is observed in the negroes brought from Central Africa and domesticated for generations in much colder latitudes.
Completed epoch of completed growth appears to bear a fixed relation to the height. The taller the individual the longer he will require to attain his full stature. This is not so natural a conse quence as it may seem at first sight, as the rate of growth is by no means uniform, most of the height being attained long before the growth ceases. By a comparison of the statistics obtained during our war with similar European tables, it is shown that in Central Europe the growth generally ceases by the twenty-first year, while in this country it continues to the twenty-fourth year, and not rarely to the thirtieth.