One has to be careful how one reads.  A few years ago I used this short bit from Darwin’s Descent of Man (page 174) to tease a Welsh friend:
Given a land originally peopled by a thousand Saxons and a thousand Celts — and in a dozen generations five-sixths of the population would be Celts, but five-sixths of the property, of the power, of the intellect, would belong to the one-sixth of Saxons that remained.  In the eternal ‘struggle for existence,’ it would be the inferior and less favoured race that had prevailed — and prevailed by virtue not of its good qualities but of its faults.
However, it turns out that these are not the words of Darwin himself, but he is quoting a certain Mr. Greg.  Here is with an earlier bit, is more of the passage in question:
A most important obstacle in civilised countries to an increase in the number of men of a superior class has been strongly urged by Mr. Greg and Mr. Galton, namely, the fact that the very poor and reckless, who are often degraded by vice, almost invariably marry early, whilst the careful and frugal, who are generally otherwise virtuous, marry late in life, so that they may be able to support themselves and their children in comfort.  Those who marry early produce within a given period not only a greater number of generations, but, as shewn by Dr. Duncan, they produce many more children.  The children, moreover, that are born by mothers during the prime of life are heavier and larger, and therefore probably more vigorous, than those born at other periods.  Thus the reckless, degraded, and often vicious members of society, tend to increase at a quicker rate than the provident and generally virtuous members.  Or as Mr. Greg puts the case: “The careless, squalid, unaspiring Irishman multiplies like rabbits: the frugal, foreseeing, self-respecting, ambitious Scot, stern in his morality, spiritual in his faith, sagacious and disciplined in his intelligence, passes his best years in struggle and in celibacy, marries late, and leaves few behind him.  Given a land originally peopled by a thousand Saxons and a thousand Celts — and in a dozen generations five-sixths of the population would be Celts, but five-sixths of the property, of the power, of the intellect, would belong to the one-sixth of Saxons that remained.  In the eternal ‘struggle for existence,’ it would be the inferior and less favoured race that had prevailed — and prevailed by virtue not of its good qualities but of its faults.”
There are, however, some checks to this downward tendency.
See what a little bit of extra reading does!  It appears that Mr. Greg did not classify the Scots as “Celts”, but rather as “Saxons”.  Moreover, I wonder what Alfred Russel Wallace, born in the Welsh village of Llanbadoc, would have made of that.

William Rathbone Greg (1809 –1881) was English essayist, a species, to judge from the abundant literary fossils from the Victorian strata, were quite abundant at that time.  G.K. (Gilbert Keith) Chesterton (1874 – 1936) was a British writer and philosopher who could be said to also belong to that species.  He started out well-disposed towards Darwin.  In 1903 he wrote:
Of the thousands of brilliant and elegant persons like ourselves who believe roughly in the Darwinian doctrine,
And in “Heretics” (1905) he wrote:
I myself, to take a corpus vile, am very certain that I would not read the works of Comte through for any consideration whatever. But I can easily imagine myself with the greatest enthusiasm lighting a bonfire on Darwin Day.
But because of his opposition to Eugenics, he became over the years an antagonist of the Evolutionists, as he called them, though to my knowledge he never wrote anything derogatory about Darwin himself.  However, it is with the context of race that I am concerned here.
Chesterton became very Catholic in persuasion long before he was admitted to the Holy Roman Catholic and Apostolic Church, and viewed the evils of Capitalism as in many ways arising out of the Protestant Whig ascendancy in Britain.  He viewed the Reformation as wrong, but even so:
Luther was subject to irrational convulsions of rage, in one of which he tore out the Epistle of St. James from the Bible, because St. James exalts the importance of good works.  But I shudder to imagine into what sort of epileptic convulsion he would have fallen if anybody had told him to tear out the Epistles of St. Paul, because St. Paul was not an Aryan.  Luther, if possible, rather exaggerated the weakness of humanity, but at least it was the weakness of all humanity.  John Knox achieved that queer Puritan paradox, of combining the same concentrated invocation of Christ with an inhuman horror and loathing for all the signs and forms and traditions generally characteristic of Christians.  He combined, in the way that puzzles us so much, the adoration of the Cross with the abomination of the Crucifix.  But at least John Knox would have exploded like dynamite, if anybody had asked him to adore the Swastika.  All this new Nordic nonsense would seem to have nothing whatever to do with Protestant theology; or rather to be completely contrary to it. 
From The Well and the Shallows (1935).  In some respects, he seems to have regarded Protestantism and Islam as similar developments.  In A Note on Comparative Religion, he wrote:
Islam, if it is to go into a class at all, ought not to go into a class of Islam, Christianity, Confucianism and Brahminism, but rather into a class of Islam, Manicheeism, Pelagianism and Protestantism.
And even though he accepted neither, he states quite categorically that racialism belongs in neither.  In The Way of the Desert, from The New Jerusalem (1920):
And it has been one of the merits of the Moslem faith that it felt men as men, and was not incapable of welcoming men of many different races. . . . .  When a man in the desert meets another man [he] does not shout at him and ask whether he had a university education, or whether he is quite sure he is purely Teutonic and not Celtic or Iberian.  A man is a man; and a man is a very important thing.  One thing redeems the Moslem morality which can be set over against a mountain of crimes; a considerable deposit of common sense.  And the first fact of common sense is the common bond of men. . . . When he does distinguish somebody not as a man but as a Moslem, then he divides the Moslem from the non-Moslem exactly as he divides the man from the camel.  But even then he recognises the equality of men in the sense of the equality of Moslems.  He does not, for instance, complicate his conscience with any sham science about races. . . . If he is not considering somebody as a Moslem, he will consider him as a man.  At the price of something like barbarism, he has at least been saved from ethnology.
The sham science about races certainly reminds one of the article by Gerhard Adam Why Race Is Pseudo-Science.

Shortly after returning from a trip across the Atlantic. he published What I Saw In America (1922).  The aftermath of slavery concerned him greatly, and he gave this historical analysis:
The facts show that, in this problem of the Old South, the eighteenth century was more liberal than the nineteenth century.  There was more sympathy for the negro in the school of Jefferson than in the school of Jefferson Davis.  Jefferson, in the dark estate of his simple Deism, said the sight of slavery in his country made him tremble, remembering that God is just.  His fellow Southerners, after a century of the world’s advance, said that slavery in itself was good, when they did not go farther and say that negroes in themselves were bad.  And they were supported in this by the great and growing modern suspicion that nature is unjust.  Difficulties seemed inevitably to delay justice, to the mind of Jefferson; but so they did to the mind of Lincoln.  But that the slave was human and the servitude inhuman — that was, if anything, clearer to Jefferson than to Lincoln.  The fact is that the utter separation and subordination of the black like a beast was a progress; it was a growth of nineteenth-century enlightenment and experiment; a triumph of science over superstition.  It was ‘the way the world was going,’ as Matthew Arnold reverentially remarked in some connection; perhaps as part of a definition of God.  Anyhow, it was not Jefferson’s definition of God.  He fancied, in his far-off patriarchal way, a Father who had made all men brothers; and brutally unbrotherly as was the practice, such democratical Deists never dreamed of denying the theory.  It was not until the scientific sophistries began that brotherhood was really disputed.  Gobineau [1], who began most of the modern talk about the superiority and inferiority of racial stocks, was seized upon eagerly by the less generous of the slave-owners and trumpeted as a new truth of science and a new defence of slavery.  It was not really until the dawn of Darwinism, when all our social relations began to smell of the monkey-house, that men thought of the barbarian as only a first and the baboon as a second cousin. 
Chesterton was deeply opposed to imperialism, being one of the few journalists at the time who opposed the Boer War.  One British imperial figure for whom he seems to have held deep disdain was Cecil Rhodes:
but Cecil Rhodes had no principles whatever to give to the world.  He had only a hasty but elaborate machinery for spreading the principles that he hadn’t got.  What he called his ideals were the dregs of a Darwinism which had already grown not only stagnant, but poisonous.  That the fittest must survive, and that any one like himself must be the fittest; that the weakest must go to the wall, and that any one he could not understand must be the weakest; that was the philosophy which he lumberingly believed through life, like many another agnostic old bachelor of the Victorian era. . . .
There is an obvious and amusing proof of this in a recent life of Rhodes.  The writer admits with proper Imperial gloom the fact that Africa is still chiefly inhabited by Africans.
From The Sultan (1912).  Back to the original observation of being careful about how one reads.  In Chesterton’s work one occasionally comes across a widespread derogatory term for black people.  However, he is there projecting into the mind of the derogatory person, not expressing himself.
But if there is one thing psychologically certain, it is that men cannot live wholly by instincts, even wholesome instincts.  Men must have theories — even to build a wall.  It is neither respectful to them, nor dignified in us, that we should always dance round them and implore them to accept our creed.  They will find the truth, as we have found it, who deserved it so much less.  And the truth is that a man’s philosophy of the cosmos is directly concerned in every act of his life.  Call theories threads of cotton; still the strain of life is on those threads.  Call the metaphysics of free will a mere cob-web; still in the hour of temptation everything will hang on that cob-web.  Call the mystical nature of man a mere fancy; the time may come when nothing but that prevents you from shooting a n___r.
I expect this last sentence will provoke a degree of protest from persons of a non-religious or anti-religious persuasion, and unwarranted agreement from those of the opposite (though I suspect fewer of those will be reading this site.)  However, the following, from The Empire of the Insect (1910):
A cultivated Conservative friend of mine once exhibited great distress because in a gay moment I once called Edmund Burke an atheist.  I need scarcely say that the remark lacked something of biographical precision; it was meant to.  Burke was certainly not an atheist in his conscious cosmic theory, though he had not a special and flaming faith in God, like Robespierre.  Nevertheless, the remark had reference to a truth which it is here relevant to repeat.  I mean that in the quarrel over the French Revolution, Burke did stand for the atheistic attitude and mode of argument, as Robespierre stood for the theistic.  The Revolution appealed to the idea of an abstract and eternal justice, beyond all local custom or convenience.  If there are commands of God, then there must be rights of man.  Here Burke made his brilliant diversion; he did not attack the Robespierre doctrine with the old mediaeval doctrine of *jus divinum* (which, like the Robespierre doctrine, was theistic), he attacked it with the modern argument of scientific relativity; in short, the argument of evolution.  He suggested that humanity was everywhere moulded by or fitted to its environment and institutions; in fact, that each people practically got, not only the tyrant it deserved, but the tyrant it ought to have.   “I know nothing of the rights of men,” he said, “but I know something of the rights of Englishmen.” There you have the essential atheist.  His argument is that we have got some protection by natural accident and growth; and why should we profess to think beyond it, for all the world as if we were the images of God! We are born under a House of Lords, as birds under a house of leaves; we live under a monarchy as n___s live under a tropic sun; it is not their fault if they are slaves, and it is not ours if we are snobs.
There are many reasons why I find Chesterton helpful in preserving a sense of proportion.  I only discovered him in 2008, and used to take along one or another collection of his essays on beamline trips to ISIS as a “sanity book”.  But for things not in our university library, I have also found the Internet a useful resource.

One thing that has got out of proportion is trying to control the developing attitudes of our children, even to attempting to ban Golliwogs as leading to racism.  In Cockneys and their Jokes (1915) he writes:
Quite equally subtle and spiritual is the idea at the back of laughing at foreigners. It concerns the almost torturing truth of a thing being like oneself and yet not like oneself. Nobody laughs at what is entirely foreign; nobody laughs at a palm tree. But it is funny to see the familiar image of God disguised behind the black beard of a Frenchman or the black face of a Negro. There is nothing funny in the sounds that are wholly inhuman, the howling of wild beasts or of the wind. But if a man begins to talk like oneself, but all the syllables come out different, then if one is a man one feels inclined to laugh, though if one is a gentleman one resists the inclination.
One may ask, why rake over this old history?  There are two reasons, the first being that a false account of history leads to wrong conclusions and wrong actions.

The second is that these issues are still relevant today.  Only a couple of days ago I read an article:
International Criminal Court is ‘hunting’ Africans — The African Union has said that it will complain to the United Nations about the International Criminal Court (ICC) “hunting” Africans because of their race.

There are many reasons why African rulers figure disproportionately in ICC prosecutions, many of them ‘natural’ but arguably unfair.  But race, in my view, has very little to do with it.

[1] Joseph Arthur Comte de Gobineau, An Essay on the Inequality of the Human Races (1853–1855)