THE EVOLUTION OF MAN.
Essays on the Evolution of Man. By Elliot Smith. (Oxford University Press. 8s. 6d.) PROFESSOR ELLIOT SMITH is well known as one of the rare men who, like the late W. H. Rivers, come to anthropology with a wide apparatus of training in other branches of science. Primarily a comparative anatomist, he then turned to physical and then to cultural anthropology ; it is in the former that he has perhaps made his most notable contributions to science, although he is better known to the man in the street for his theories of the spread of culture.
In this small volume—three lectures reprinted and some- what revised—he touches on all sides of the subject. He has been wise enough to see at the outset the elementary but too often neglected fact that there have been two wholly distinct periods in the evolution of man, in which quite different methods of evolution were at work. The first comprises all that long space when from some pre-human ancestor there developed something that could be called a man, and that further space during which these early men gave place to man as we now know him. During this period, the main change was in the instrument, in the body and brain of man himself : evolution was working with the same methods as she had employed with all other animals and plants. After this came another period, comprising all that we know as history as well as many millennia before it, during which, although equally revolutionary changes have been wrought, and at even greater speed, the change has been only in negligible degree in the instrument, almost wholly in the performance : the evolution has been an evolution of culture, passed on by the new method added to nature's workshop—the method of tradition.
What organ or activity was it which led the way in the first phase of human evolution ? The question has often been asked, and has been answered in the most various ways. Professor Elliot Smith's own work on the brains of various mammals gives us reasonable assurance that it was, as might have been supposed, the brain. To put the matter rather crudely, the higher- brain-centres connected with smell and sight are in different regions, the latter being lodged in the specialized part of the cerebral hemispheres . called the neo- pallium, whose development was a special feature of mammals. When some of the early mammals took to life in the trees, it meant that smell would be less, sight more important to them ; this, again, meant that the visual centres (and so all the associated neopallium)• would be more stimulated and exercised. Life in the trees also meant a greater development of tactile discrimination. So the foundations were laid for the future brain and mind of man. Subsequent progress was in what, on the analogy of a vicious circle, we might call a " virtuous spiral," each advance in sensory power making it advantageous to develop greater delicacy in the brain centres, and vice versa--a reciprocal stimulation of tool and tool-controller.
Professor Elliot Smith sums it all up by saying that the features which essentially distinguish man's brain from the ape's are an accentuation of those which distinguish the ape's brain from the monkey's and the monkey's from the lemur's ; in fact, that in regard to brain development there has been a steady and unbroken change in one direction from the earliest mammals to man—a reminder that we should not only not despise our simian ancestors but be, grateful to them, for the very existence of our humanity has only been possible through the past existence of their simianity.
When we reach the second phase of human evolution, our author is on more controversial ground. He has come into prominence of recent years as upholding in an extreme form the doctrine that similarities of culture in- remote parts of the world or in remote times are due, not to an independent evolution, but always to diffusion from a single origin and centre. In support of this thesis he advances many evidences and arguments which will well repay the reading. Among the most interesting discussions is that concerning the various types of flint implement, in which it is clearly shown that many of the older generalizations and classifications will have to be abandoned. The succession of cultural stages found in Western Europe through the " Stone Ages" is not an inevitable or indeed a single evolutionary succession ; quite different successions and combinations of elements arc found in other parts of the world. We happen to know
the European succession the best, but are learning that it
is the result of a particular series of waves of migration which chanced to spread at just such a time and at such a rate from some other centre or centres.
So far so good. In all this section there is much that will help materially in putting things in their right perspective, and in enabling us to understand more clearly the human motives and processes behind the flints and barrows and bones which we find.
But when Professor Elliot Smith asserts that similarities of culture must always be due to diffusion, never to independent evolution, a biologist may be pardoned for wondering if he is not being too bold. There exist some very instructive biological parallels. Take for example the social insects. The bees, the wasps, and the ants are all members of the one order hymenoptera. In all of them there is found a social organization of the same type—built upon the foun- dations of a worker caste composed of sterile females. The . termites, belonging as they do to another branch altogether, have also a social organization based on worker-castes—but here the workers have been derived from males as well as females. It is natural to assume that the hymenopteran social habit has a single origin. This, however, is quite certainly not the case. Not only has it arisen independently in each of the three main types of social hymenoptera, but, as readers of Wheeler's remarkable book on social insects will remember, it has even arisen independently within these smaller groups.
We are enabled to say with reasonable certitude in such cases what resemblance is due to common descent, what to the convergence of independent evolution, because we have before us the great mass of evolutionary evidence which the detailed structure of a complex animal affords to the trained zoologist. When we are dealing with cultural remains, however, we usually possess only fragmentary evidence ;, and the problem would often appear, to our present know- ledge, to be insoluble (except dogmatically).
It seems pretty certain that the Chinese anticipated many of our Western inventions, and that these were rediscovered wholly independently ; and the history of modern science abounds with cases of discoveries and conclusions being_ independently reached by two or several workers. It does, therefore, seem dangerous to conclude that, for instance, the megalithic culture must have but one origin—in other words, that men only once had tit( idea of piling large stones' one upon the other to make sacred places.
But we all know that reformers err by excess of zeal : and there is no doubt that Professor Elliot Smith is a reformer, and a zealous one. These lectures, though hardly suitable, as a first introduction to the subject, are most certainly, to be recommended to those who already have some general knowledge of man's evolution, and desire to extend it.
J. S. HUXLEY., -
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