Hence we may say that though our knowledge of past life upon the Earth isrelatively small, yet what we have, and what we continually add to it, supportthe belief that there has been an evolution of the simple into the complexalike in individual forms and in the aggregate of forms. §121. Advance from the homogeneous to the heterogeneous is clearlydisplayed in the progress of the latest and most heterogeneous creature --Man. While the peopling of the Earth has been going on, the human organismhas grown more heterogeneous among the civilized divisions of the species;and the species, as a whole, has been made more heterogeneous by the multiplicationof races and the differentiation of them from one another. In proof of thefirst of these statements may be cited the fact that, in the relative developmentof the limbs, civilized men depart more widely from the general type of theplacental mammalia, than do the lowest men. Though often possessing well-developedbody and arms, the Papuan has very small legs: thus reminding us of the man-likeapes, in which there is no great contrast in size between the hind and forelimbs. But in the European, the greater length and massiveness of the legshas become marked -- the fore and hind limbs are relatively more heterogeneous.
The greater ratio which the cranial bones bear to the facial bones, illustratesthe same truth. Among the Vertebrata in general, evolution is marked by anincreasing heterogeneity in the vertebral column, and especially in the componentsof the skull: the higher forms being distinguished by the relatively largersize of the bones which cover the brain, and the relatively smaller sizeof those which form the jaws, etc. Now this trait, which is stronger in Manthan in any other creature, is stronger in the European than in the savage.
Moreover, from the greater extent and variety of faculty he exhibits, wemay infer that the civilized man has also a more complex or heterogeneousnervous system than the uncivilized man; and, indeed, the fact is in partvisible in the increased ratio which his cerebrum bears to the subjacentganglia. If further elucidation be needed, every nursery furnishes it. Inthe infant European we see sundry resemblances to the lower human races;as in the flatness of the alae of the nose, the depression of its bridge,the divergence and forward opening of the nostrils, the form of the lips,the absence of a frontal sinus, the width between the eyes, the smallnessof the legs. Now as the developmental process by which these traits are turnedinto those of the adult European, is a continuation of that change from thehomogeneous to the heterogeneous displayed during the previous evolutionof the embryo; it follows that the parallel developmental process by whichthe like traits of the barbarous races have been turned into those of thecivilized races, has also been a continuation of the change from the homogeneousto the heterogeneous. The truth of the second statement is so obvious asscarcely to need illustration. Every work on Ethnology, by its divisionsand subdivisions of races, bears testimony to it. Even were we to admit thatMankind originated from several separate stocks, it would still remain truethat as, from each of these stocks, there have sprung many now widely differenttribes, which are proved by philological evidence to have had a common origin,the race as a whole is more heterogeneous than it once was. Add to whichthat we have, in the Anglo-Americans, an example of a new variety arisingwithin these few generations; and that, if we may trust to the descriptionsof observers, we are likely soon to have another such in Australia. §122. On passing from Humanity under its individual form to Humanityas socially embodied, we find the general law still more variously exemplified.
The change from the homogeneous to the heterogeneous is displayed equallyin the progress of civilization as a whole, and in the progress of everytribe or nation; and it is still going on with increasing rapidity.
