THE CRADLE OF MANKIND
Man is an immensely ancient animal. Over a million years have elapsed since he first made fire and more millions since he became a bipedal prehuman. He left the forests, at the latest, at the end of the Miocene, not less than seven million years ago and ventured out into the plains of Central Asia as a savage, powerful, clever biped, hunting in packs, or by sheer wit securing his prey single handed by pitfalls and other devices, the invention of which marks the development of growing intelligence.
Man's initial differentiation from his simian ancestry probably began when he came down from the trees and began to walk erect. The hand was then liberated from its use as an instrument of locomotion and was devoted primarily to defense, attack, discovery, and invention. It is by means of the opportunities afforded by the hand that the human brain has evolved into man's most important factor in racial survival.
Clear evidence of man's remote arboreal ancestry is offered by his stereoscopic or double-eyed vision. The great majority of ground animals, especially those living in the forest, have eyes on the sides of their heads; but in man's arboreal ancestors, by the recession of the intervening nasal and facial bones, the eyes were brought around to the front of the face. The resulting stereoptic vision enabled him to judge distance far more accurately than most mammals. Such power of determining distance is of course vital to an arboreal animal. Failure to judge accurately the length of a leap from branch to branch would be fatal.
One often hears it stated that man has lost his sense of smell; but this sense was probably never better developed within the human period than it is now. In the trees a sense of smell is not of much value. The monkey can sit on a branch and jabber with impunity at the leopard on the ground below. To forest animals, like the deer or boar, however, the sense of smell is the surest protection against attack and is much more highly developed than the sense of sight, which latter is often quite feeble. In fact, in the thick jungle it is almost useless (and at "black night" completely so).
Eurasia, where it is probable that mankind originated, was the greatest land mass on the globe in Tertiary times. Modern Europe and North Africa formed relatively small peninsulas in the extreme west of this Tertiary land mass. It is probably from Eurasia that man spread out to the uttermost parts of the habitable globe, carrying with him his language and such cultural features as had developed at the time of each successive migration. No race or language or cultural invention seems to have entered Eurasia from adjoining land areas. All went out. None came in. While the original center of dispersal of the Hominidæ or human family was probably Eurasia, it was at a later date also the center of the evolution of the higher types of man.
To the northeast of Eurasia lay the ancient land connection with North America via Alaska, over which various species of animals passed back and forth, some of them having their origin in Asia and others in western North America. It was undoubtedly over this land connection that man first entered America at a relatively recent period and probably he came in successive waves. The American Indians appear to have been derived from the Mongoloid tribes of northeastern Asia before the latter had developed some of those extreme specializations which characterize the typical Mongols of Central Asia and China proper today. Judging from the culture which these American Indians brought with them, this migration began before 10,000 B.C.
The existing races of mankind, and those either entirely extinct or now absorbed in other races, had their distinctive areas of differentiation and periods of radiation from Eurasia over the habitable globe. The most primitive types are now found farthest from this original centre of distribution in countries where through isolation they escaped competition with the higher types which evolved later.