Beginning chapter 6, "The Science of Racial Inequality", Weikart writes p. 103:
The disabled and criminals were not the only ones whose lives were devalued by Darwinian-inspired social thought. Many social Darwinists and eugenicists consigned most of the world's population to the realm of the "inferior." They regarded non-European races as varieties of the human species - or sometimes even as completely separate species - that were not as advanced in their evolutionary development as Europeans. Of course, darwinism was not the sole culprit in the rising tide of scientific racism in the late nineteenth century, but it played a crucial role nonetheless.
Here we again see Weikart's tendency to twist things. Those Darwinists who considered non-European races to be varieties of the human species also considered European races to be varieties of the human species.
In "The Descent of Man", chapter 7, "On the Races of Man", Darwin writes:
It is not my intention here to describe the several so-called races of men; but I am about to enquire what is the value of the differences between them under a classificatory point of view, and how they have originated. In determining whether two or more allied forms ought to be ranked as species or varieties, naturalists are practically guided by the following considerations; namely, the amount of difference between them, and whether such differences relate to few or many points of structure, and whether they are of physiological importance; but more especially whether they are constant.
While Darwin, like everybody else divided humans into races, his intrerest clearly wasn't racist. Actually Darwin was trying to go beyond superficial differences.
This is even clearer later in the same chapter, where Darwin writes:
Even the most distinct races of man are much more like each other in form than would at first be supposed; certain negro tribes must be excepted, whilst others, as Dr. Rohlfs writes to me, and as I have myself seen, have Caucasian features. This general similarity is well shewn by the French photographs in the Collection Anthropologique du Museum de Paris of the men belonging to various races, the greater number of which might pass for Europeans, as many persons to whom I have shewn them have remarked. Nevertheless, these men, if seen alive, would undoubtedly appear very distinct, so that we are clearly much influenced in our judgment by the mere colour of the skin and hair, by slight differences in the features, and by expression.
It is not that Darwin didn't recognize differences, both physiologically and otherwise. For instance, he writes:
The races differ also in constitution, in acclimatisation and in liability to certain diseases. Their mental characteristics are likewise very distinct; chiefly as it would appear in their emotional, but partly in their intellectual faculties. Every one who has had the opportunity of comparison, must have been struck with the contrast between the taciturn, even morose, aborigines of S. America and the light-hearted, talkative negroes. There is a nearly similar contrast between the Malays and the Papuans (4. Wallace, 'The Malay Archipelago,' vol. ii. 1869, p. 178.), who live under the same physical conditions, and are separated from each other only by a narrow space of sea.
Darwin continues discussing back and forth whether human races should be considered separate species or not, and after that he writes:
But the most weighty of all the arguments against treating the races of man as distinct species, is that they graduate into each other, independently in many cases, as far as we can judge, of their having intercrossed. Man has been studied more carefully than any other animal, and yet there is the greatest possible diversity amongst capable judges whether he should be classed as a single species or race, or as two (Virey), as three (Jacquinot), as four (Kant), five (Blumenbach), six (Buffon), seven (Hunter), eight (Agassiz), eleven (Pickering), fifteen (Bory St. Vincent), sixteen (Desmoulins), twenty-two (Morton), sixty (Crawfurd), or as sixty-three, according to Burke. (18. See a good discussion on this subject in Maitz, 'Introduction to Anthropology,' Eng. translat., 1863, pp. 198-208, 227. I have taken some of the above statements from H. Tuttle's 'Origin and Antiquity of Physical Man,' Boston, 1866, p. 35.) This diversity of judgment does not prove that the races ought not to be ranked as species, but it shews that they graduate into each other, and that it is hardly possible to discover clear distinctive characters between them.
Clearly, Darwin goes against the trend, and the key factor here is gradualism. The races cannot be classified as species, because they graduate into each other. He even writes, in the preceeding paragraph:
The shape of the skull varies much in some races (17. For instance, with the aborigines of America and Australia, Prof. Huxley says ('Transact. Internat. Congress of Prehist. Arch.' 1868, p. 105), that the skulls of many South Germans and Swiss are "as short and as broad as those of the Tartars," etc.); and so it is with every other character. Now all naturalists have learnt by dearly bought experience, how rash it is to attempt to define species by the aid of inconstant characters.
So, things are more complicated than Weikart describes. Of couse, one might conjecture, if skulls of South Germans and Swiss are as short and as broad as those of the Tartars, then racial mixture has happened, and we would need to use eugenics to bring back the pure Aryan race. Ans that's what Weikart should have noticed; Nazi racism wasn't 'Darwinian', but based on the assumption of the existence of a pure race in prior times, before the race degenerated by racial mixing.
Haeckel followed the trend, and in his book The Natural History of Creation, chapter 23, "Migration and Distribution of Mankind. Human Species and Human races", he writes:
All these five races of men, according to the Jewish legend of creation, are said to have descended from "a single pair" - Adam and Eve, - and in accordance with this are said to be varieties of one kind or species. If, however we compare them without prejudice, there can be no doubt that the differences of these five races are as great and even greater than the "specific differences" by which zoologists and botanists distinguish recognized "good" animal and vegetable species ("bonæ species").
Apparently, Darwin and Haeckel didn't quite agree. In the "Introduction" to The Descent of Man Darwin wrote:
Another work has (1869) been published by Dr. Francesco Barrago, bearing in Italian the title of "Man, made in the image of God, was also made in the image of the ape."), and especially by Haeckel. This last naturalist, besides his great work, 'Generelle Morphologie' (1866), has recently (1868, with a second edition in 1870), published his 'Naturliche Schopfungsgeschichte,' in which he fully discusses the genealogy of man. If this work had appeared before my essay had been written, I should probably never have completed it.
Although this might appear as a full endorsement of Haeckel account, Darwin in The Descent of Man did not fully agree with Haeckel's division of humans into species, of which Haeckel by the way counted with twelve, although he could of course also like everybody else write about "the human race", as if there were only one race and not several species.
Continuing, Weikart writes:
Racism obviously predated Darwinism, but during the nineteenth century - in psrt through the influence of Darwinism - it would undergo significant transformations. Before the nineteenth century, the intellectual dominance of Christianity militated against some of the worst excesses of racism. Christian theology taught the universal brotherhood of all races, who descended from common ancestors - Adam and Eve. Most Christians believed that all humans, regardless of race, were created in the image of God and possessed eternal souls. This meant that all people are extremely valuable, and it motivated Europeans to send missionaries to convert natives of other regions to Christianity.
Weikart does admit that this is not the complete picture:
Even though some Christian groups, especially in lands with race-based slavery, developed theological justifications for racial inequality, most Christian churches believed that people of other races were valuable and capable of adopting European religion and culture.
Things aren't quite as simple as that. We need not even go into, whether this is simply a defense of European cultural imperialism or not. Sure, Christian theology taught that all humans were descended from Adam and Eve; but how about devils? And there is also that thing with the Flood and the different destinies of the descendants of each of Noah's three sons.
Henry Morris, founder of the Institute for Creation Research (ICR), writes in The Beginning Of the World:
The descendants of Ham were marked especially for secular service to mankind. Indeed they were to be 'servants of servants,' that is 'servants extraordinary!' Although only Canaan is mentioned specifically (possibly because the branch of Ham's family through Canaan would later come into most direct contact with Israel), the whole family of Ham is in view. The prophecy is worldwide in scope and, since Shem and Japheth are covered, all Ham's descendants must be also. These include all nations which are neither Semitic nor Japhetic. Thus, all of the earth's 'colored' races,--yellow, red, brown, and black--essentially the Afro-Asian group of peoples, including the American Indians--are possibly Hamitic in origin and included within the scope of the Canaanitic prophecy, as well as the Egyptians, Sumerians, Hittites, and Phoenicians of antiquity.
Sure, Morris writes that the Hamites were to be the most excellent servants; but that was also their limit:
Yet the prophecy again has its obverse side. Somehow they have only gone so far and no farther. The Japhethites and Semites have, sooner or later, taken over their territories, and their inventions, and then developed them and utilized them for their own enlargement. Often the Hamites, especially the Negroes, have become actual personal servants or even slaves to the others. Possessed of a genetic character concerned mainly with mundane matters, they have eventually been displaced by the intellectual and philosophical acumen of the Japhethites and the religious zeal of the Semites.
Morris was certainly no Darwinist, and Weikart might claim the he had been influenced by Darwinist thinking, Morris' argumentation actually is pre-Darwin. Many Christian chrurches in the USA defended even before 1859 slavery with this argumentation. Weikart does not deny this; but he could have made more out of the point. The humanist Christianity that Weikart is so happy about isn't the only variety, neither in the 19th century nor today.
Both Darwin and Haeckel claimed that there was only a quantitative, not a qualitative difference between the mental abilities of animals and humans. This Weikart admits; but on p. 105 he writes:
On the other hand, he [Darwin] explained that some races have much lower intellectual and moral faculties than Europeans. Emphasizing racial inequality thus served an important function in Darwin's attempt to bridge the chasm between primates and humans. Even though he opposed slavery and sometimes expressed sympathy for non-European races, nonetheless he believed a wide gap separated the "highest races" from the "lowest savages", as he called them, who were inferior intellectually and morally akin to Europeans. This was not just a peripheral point of Descent, for in the introduction Darwin clearly stated that one of the three goals of his book was to consider "the value of the differences between the so-called races of man."
True, and yet Weikart gets it wrong. What Darwin refers to by "the value of the differences" is their classificatory value, as can be seen from the quote above from The Descent of Man, chapter 7. And Darwin ended up finding that there weren't any systematic differences that could be used for dividing humans into separate species. Approaching a conclusion regarding whether humans comprise one or several species, Darwin writes:
As it is improbable that the numerous and unimportant points of resemblance between the several races of man in bodily structure and mental faculties (I do not here refer to similar customs) should all have been independently acquired, they must have been inherited from progenitors who had these same characters.
What Darwin implies here is that there are no significant differences between the human races when regarding bodily structure and mental faculties, although such differences may exist regarding (social) customs.
Weikart spends the following pages describing racism among German Darwinists, and in p. 116 he writes:
The acceptance of Darwinism by the German anthropological community thus produced a shift from racial egalitarianism to inegalitarianism and a replacement of liberal, humanitarian ethics with evolutionary ethics.
This is rather questionable, as I have indicated above. Rather we must ask, why did Darwinism take this form in Germany? Weikart has this far offered us nothing that could answer this question. How could acceptance of Darwinism have produced such a shift? It most likely didn't, Darwinism was more likely employed for purposes that were produced by other mechanisms. This is a point, where Weikart, the historian, fails to do his job. Everybody can come up with long lists of selective quoting; but all of this doesn't really tell us anything.
However, things are going to improve somewhat. At the bottom of p. 117, Weikart quotes Alfred Ploetz:
Through reading the works of Darwin, Haeckel and other biologists already at school, as well as through some novels by Felix Dahn and other glorifiers of German antiquity and medieval times I was permanently enthused for the Germanic race ... and determined to make it my life's task ... to help in Germany and other states with German-speaking populations to lead it upward again to purity and the height of the first millenia.
All in all, this is not Darwinism, but a romantic idea of a past glory that can come true again. Ploetz' tool for the realization of this idea was race hygiene, a peculiar form of eugenics.
On p. 118, Weikart writes:
In coining the term race hygiene, he [Ploetz] preferred it becausethe hygiene of the entire human species coincides with that of the Aryan [= German] race, which, except for a few smaller races, like the Jewish - which in any case is probably mostly Aryan - represents the civilized race par excellence; to further it [the Arayan race (RW)] is the same as furthering all of humanity.
That Ploetz's race hygiene was not supposed to benefit all races was also apparent in his statement that the love of humanity "is nothing more than love for its Aryan part."
Aren't we a bit far away from anything that has much to do with darwin's theory of evolution here? The German nationalism in the Second Reich wasn't produced by Darwinism. Also Ploetz' race hygiene is really a very different concept than Francis Galton's eugenics.