It is obviously impossible to enter at any length into any one of these topics of inquiry, within the limits of the present article ; and all that will be here attempted, will be to place before the reader a general resume of the whole subject, carrying out those portions into some what more of detail, in which the anatomist and physiologist are most concerned.
The question at issue has usually been con sidered under the simple aspect of specific unity or diversity; — that is, in the first place, whether all the existing races may be sup posed to be the descendants of one pair of " protoplasts ;" all their diversities in physical conformation, in language, in mental character, and in social condition, having since arisen ; —or whether, secondly, ihe existing races must be regarded as having sprung from several distinct pairs of protoplasts ; which originally presented differences amongst themselves, nearly the same with those which now exist amongst the races that seem most remote from each other. Now the first of these suppositions requires that evidence should he given of a very considerable amount of vari ability from the original type (whatever that may have been) amongst the descendants from the common ancestry : whilst the second is based on the idea, that the leading characters which now separate the different races are per manent, and must have been presented by their original progenitors. A third supposition, which has been put forward within the last few years, regards the existing races as not all proceeding from one pair of " protoplasts," but from several; but considers that these, though scattered over the globe, were funda mentally similar in corporeal and mental con stitution, and differed only in the adaptation of certain of their physical characters to the different circumstances of their several abodes, — thus being all comprehensible within the limits of one species,— and all possessing, too, a certain capacity for variation, which has been manifested in the production of subor dinate diversities, and has even proceeded, in some instances, under the prolonged influence of change of climate, civilization, &c., to soften down, if not entirely to obliterate, the original differences. On the general bearing of the last of these hypotheses, a few remarks seem called for.
Although the same affinity or blood-rela tionship would not exist between the de scendants of several distinct pairs of " proto plasts," as between those of a common ancestry, yet the moral relations between them would be as close as on the supposition of their consanguinity. For, as has been justly observed, " the moral rights of men depend on their moral nature ; and while Africans have the hearts and consciences of human beings, it could never be right to treat them as domestic cattle or as wild fowl, if it were ever so abundantly demonstrated that their race was but an improved species of ape, and ours a degenerate kind of god."* This view has recently been very forcibly urged by Professor Agassiz, who has adopted in regard to the human races the same views as he has put forth with respect to many other species (p. 1310.) ; and who thus upholds the " unity of mankind," whilst contending for the diversity of " protoplasts." " We recognise," he says, "the fact of the unity of mankind. It excites afeeling that raises men to the most elevated sense of their connec tion with each other. It is but the reflection of that Divine nature which pervades their whole being. It is because men feel thus related to each other that they 'acknowledge those ob ligations of kindness and moral responsibility which rest upon them in their mutual relations. And it is because they have this innate feeling, that they are capable of joining in regular societies, with all their social and domestic affinities. This feeling unites men from the
most diversified regions. Do we cease to recognise this unity of mankind, because we are not of the same family, because we ori ginate in various countries, and are born in America, England, Germany, France, Switzer land ? Where the relationship of blood has ceased, do we cease to acknowledge that ge neral bond which unites all men of every na tion? By no means. This is a bond which every man feels more and more, the farther he advances in his intellectual and moral culture, and which in this development is continually placed upon higher and higher ground ; so much so, that the physical relation arising from a common descent is finally entirely lost sight of, in the consciousness of the higher moral obligations. It is this consciousness which constitutes the true unity of mankind." This unity, he continues, may become a yet stronger bond of moral affinity, than that afforded by community of descent. "Where men of the same nation, individuals whose studies, whose calling in life have developed in them the same faculties, the same feelings, are brought closely together, relations spring up between them so intimate as by far to outweigh the natural bonds which a com mon parentage may establish between men. Such individuals do not feel themselves to be near each other, do not sympathise in their aspirations, do not join in the same purposes, because they are brothers, because they belong to the same family, because they are of the same nation ; but because they feel that they are men, and that the natural dispositions wherewith they are endowed as men are de veloped in them in a similar manner, and with reference to the same great human interests. Is there any one who would consider the ties between two such individuals on that intel lectual and moral ground, as lessened because they may not be physically related at all ? or who would consider the differences in their physical features as an objection to their being more intimately connected than other men who in features resembled them more, or are related to them more closely, perhaps by the nearest ties of blood ? We can therefore take it as a matter of fact, that, as we find men actually living together in the world, it is not the physical relation which establishes the closest connection between them, but that higher relation arising from the intellectual constitution of man." Professor Agassiz then refers to various departments of Natural His tory, as affording proof " that the closest and most intimate unity may exist without a com mon origin, without a common descent, with out that relationship which is often denoted by the expression ' ties of blood.' On the other hand, that these ties of blood may exist, without necessarily calling forth the higher connections which may be found 1)etween in dividuals of the same type, is, alas I too plainly shown by the history of mankind. The im mediate conclusion from these facts, however, is the distinction we have made above, that to acknowledge a unity in mankind, to show that such a unity exists, is not to admit that men have a common origin, nor to grant that such a conclusion may be justly derived from such premises. We maintain, therefore, that the unity of mankind does not imply a com munity of origin for men ; we believe, on the contrary, that a higher view of this unity of mankind can be taken, than that which is de rived from a mere sensual connection; that we need not search for the highest bond of humanity in a mere animal function, whereby we are most closely related to the brutes."# The Anatomical differences by which the several races of Mankind are distinguished from each other, may be referred to the fol lowing heads: — I. Conformation of the cranium.