HKB
Antiquity and Persistence in Character of the existing Races of Mankind. Theory of their Unity of Origin considered. Bearing of the Diversity of Races on the Doctrine of Transmutation. Difficulty of defining the Terms "Species" and "Race." Lamarck's Introduction of the Element of Time into the Definition of a Species. His Theory of Variation and Progression. Objections to his Theory, how far answered. Arguments of modern Writers in favour of Progression in the Animal and Vegetable World. The old Landmarks supposed to indicate the first Appearance of Man, and of different Classes of Animals, found to be erroneous. Yet the Theory of an advancing Series of Organic Beings not inconsistent with Facts. Earliest known Fossil Mammalia of low Grade. No Vertebrata as yet discovered in the oldest Fossiliferous Rocks. Objections to the Theory of Progression considered. Causes of the Popularity of the Doctrine of Progression as compared to that of Transmutation.
When speaking in a former work of the distinct races of mankind,* I remarked that, "if all the leading varieties of the human family sprang originally from a single pair" (a doctrine, to which then, as now, I could see no valid objection), "a much greater lapse of time was required for the slow and gradual formation of such races as the Caucasian, Mongolian, and Negro, than was embraced in any of the popular systems of chronology."
(* "Principles of Geology" 7th edition page 637, 1847; see also 9th edition page 660.)
In confirmation of the high antiquity of two of these, I referred to pictures on the walls of ancient temples in Egypt, in which, a thousand years or more before the Christian era, "the Negro and Caucasian physiognomies were portrayed as faithfully, and in as strong contrast, as if the likenesses of these races had been taken yesterday." In relation to the same subject, I dwelt on the slight modification which the Negro has undergone, after having been transported from the tropics and settled for more than two centuries in the temperate climate of Virginia. I therefore concluded that, "if the various races were all descended from a single pair, we must allow for a vast series of antecedent ages, in the course of which the long-continued influence of external circumstances gave rise to peculiarities increased in many successive generations and at length fixed by hereditary transmission."
So long as physiologists continued to believe that Man had not existed on the earth above six thousand years, they might with good reason withhold their assent from the doctrine of a unity of origin of so many distinct races but the difficulty becomes less and less, exactly in proportion as we enlarge our ideas of the lapse of time during which different communities may have spread slowly, and become isolated, each exposed for ages to a peculiar set of conditions, whether of temperature, or food, or danger, or ways of living. The law of the geometrical rate of the increase of population which causes it always to press hard on the means of subsistence, would ensure the migration in various directions of offshoots from the society first formed abandoning the area where they had multiplied. But when they had gradually penetrated to remote regions by land or water--drifted sometimes by storms and currents in canoes to an unknown shore--barriers of mountains, deserts, or seas, which oppose no obstacle to mutual intercourse between civilised nations, would ensure the complete isolation for tens or thousands of centuries of tribes in a primitive state of barbarism.