We may further assume that the environment in which man primarily evolved was not a moist tropical climate, but a temperate and more or less arid one, progressively cold and dry during the course of his evolution. In this region and under these conditions, the race first attained a dominance which enabled it to spread out in successive waves of migration to the most remote parts of the earth.” We do not know anything of the migrations of the Eolithic and earlier Palæolithic races, except that they spread rapidly over a considerable portion of the earth. Both migration and evolution, especially mental evolution, must have been accelerated by the great changes of climate which were taking place. In the Mindel-Riss interglacial period we know of two types, the Piltdown man (_Eoanthropus dawsoni_) and the Heidelberg man (_Homo heidelbergensis_), the latter a true man, though probably not on the direct line of evolution of _Homo sapiens_. The stress of the succeeding second Glacial period was too great for _Eoanthropus_, which appears to have died out, but _Homo_, probably an Asiatic or African type similar to _H. Heidelbergensis_, survived. The next form, associated with Mousterian implements, is Neanderthal man (_H. neanderthalensis_), who closely resembled modern man, and all the remains of races which lived subsequently to the last glaciation are those of modern man (_H. sapiens_), including the magnificent Cro-Magnards and the negroid Grimaldi race. Thus each glaciation has been marked by a step upwards in the scale of humanity; does this mean that the coming of the super-man is contingent on another glacial epoch? BIBLIOGRAPHY Barrell, J. “Probable relations of climatic change to the origin of the Tertiary Ape-man.” _Scientific Monthly_, New York, 4, 1917, p. 16. Mathew, W. D. “Climate and evolution.” _Annals New York Acad. Sci._, 24, 1915, p. 212. London, British Museum. “A guide to the fossil remains of man....” London, 1918. CHAPTER XIX CLIMATE AND HISTORY It is a remarkable fact in human history that civilization began in regions which are at present inhabited chiefly by backward races, and the centres of progress have shifted from one country to another with the passage of time. Many accidental factors—position on trade-routes, possession of special mineral advantages, and so on, have undoubtedly played a part in this, but it will not be difficult to show that climatic fluctuations have also had their share.