In ethnography, those geographical areas whose physical conditions have left a durable impress on their human inhabitants have been called either “geographical provinces” (Bastian) or “areas of characterization” (de Quatrefages). I prefer and shall adopt the latter as more indicative of the meaning of the term. It signifies that like physio-geographical conditions prevailing over a given area inhabited for many generations by the same peoples have impressed upon them certain traits, physical and psychical, which have become hereditary and continue indeterminately, even under changed conditions of existence.

This general law is the recognized basis of modern scientific ethnography.[48] It is open to numerous limitations, and its application must never be made without the consideration of accessory and modifying circumstances. For instance, certain areas are much more potent than others in the influence they exert on man: some act more powerfully on his mind than on his body, or the reverse; some peoples are more susceptible to physical influences of a given class than others; and the length of time required is variable.

Scheme of Geologic Time during the Age of Man in the Eastern Hemisphere.

Quaternary,
Diluvial
or
Pleistocene
Epoch.		1. Pre-glacial.Europe connected with Africa.Man homogeneous.
Temperature mild.Industry palæolithic with simple implements.
African elephant in England.Migrations extensive.
Tropical animals abundant.Language rudimentary.
2. Glacial.Europe severed from Africa.Man dividing into races.
Temperature low.Industry palæolithic with compound implements.
Reindeer in France.Cave dwellings.
Arctic animals abundant.Migrations limited; races in fixed areas.
3. Post-glacial.Continents assume present forms.Races completely established.
Temperature rising.Industry neolithic.
Temperate zones established.Beginning of sedentary life.
Languages developed in classes.
Present
or
Alluvial
Epoch. 		1. Pre-historic.Geographic conditions undisturbed.Races develop into contact.
Wild animals not diminished.Industry of stone and copper.
2. Proto-historic.Conditions altered by agriculture.Great migrations begin.
Wild animals slain or tamed.Industry of bronze and iron.
3. Historic.Geographic conditions greatly modified by man.Extensive mingling of races.
All lower animals subjugated.Development of nations.

According to the analogy of other organic beings, man would have been more impressible to his surroundings in the early history of his existence as a species, the young, either as an individual or a genus, being more plastic than the old. Furthermore, in his then condition of culture, or absence of culture, he had less to oppose to the assaults of his environment.

Classification of Races.—It is not possible in the present status of the science of man to point out precisely how the various conditions of the great continental areas reacted on the homogeneous primitive type to develop the races as we know them. The same difficulty encounters us with other animals and with plants. We know, however, that at the dawn of history each of these areas was peopled by nations resembling each other much more than they resembled nations of any of the other areas.

In addition to the great continents there were many lesser regions, peninsulas and islands, usually on the borders of the main areas of characterization, where intermingling of types was sure to arise, and other types be formed, who in turn received some particular impress from their environment.

These considerations prompt me to offer the following as the most appropriate scheme in the present condition of science for the subdivision of the species Man into its several races or varieties.

I. The Eurafrican Race.—Traits.—Color white, hair wavy, nose narrow, jaws straight, skull variable, languages inflectional, religions ideal.

II. The Austafrican Race.—Traits.—Color black, hair woolly, nose flat, jaws protruding, skull long, languages agglutinative, religions material.