|HOW THE EARTH WAS PEOPLED.|
WHY should the study of prehistoric man excite bitter passions? Why should it trouble timorous souls? Its aim, with real scientific inquirers, is simply to attain an objective reality, worthy of the respect of all; and it has had the happy fortune to unite in a common pursuit minds of the most diverse character, having neither the same motives nor the same tendencies, but animated by the pure desire of increasing the domain of knowledge. In this way freethinkers and priests, men of the world and men of the study, collectors, pioneers, philosophers, and practicians, whether spiritualistic and Christian or positivists, resolute partisans of the doctrine of evolution or opponents of it, have labored hand-in-hand in prehistoric investigation—that is, in collecting all the signs, observations, and things which relate to the existence of man in the times anterior to history. The objects of this study also lie back of all chronology, and it is in question whether it is possible to make an estimate of the time within which they were embraced. History, as founded on documents and monuments of definite import and intelligible traditions, goes back to the foundation of the Egyptian empire by Menes, five thousand years before Christ, and there stops. At that time, the Egyptians had an organization, a well-developed civilization, and cities. It is not hazarding too much to add as many years to the figure we have named, or to accept Plato's statement that the Egyptian people were ten thousand years old in his time.
Prehistoric times begin at this period—twelve thousand years ago—and extend back into a much more remote past. Without written data, without even conjectural dates, is it possible to estimate their duration? All that we have are the marks that man has left on Nature, who, in her incessant action burying these marks under accumulations of successive strata, gives us a kind of relative chronology. It is now admitted by science that the life of man crosses the whole Quaternary period, and if we can measure the duration of that period we shall be able to fix approximately the age of our race. This is what M. de Mortillet attempts to do in formulating the conclusions of his book on the "Prehistoric Antiquity of Man."
The circles of growth of trees on American ruins and the rates of formation of river deltas and alluvions have been made the bases of partial and doubtless insufficient calculations from which an age of five or six thousand years has been assigned to the polished-stone period of Robenhausen, and thirteen thousand years for the accumulation of Nile-mud over a brick which was found beneath a statue of