On this date, the second edition of The Descent of Man and Selection in Relation to Sex by Charles Darwin was published. It was generally the edition most commonly reprinted after Darwin’s death and up to the present. In the introduction to the first edition, Darwin gave the purpose of his treatise:
The sole object of this work is to consider, firstly, whether man, like every other species, is descended from some pre-existing form; secondly, the manner of his development; and thirdly, the value of the differences between the so-called races of man.
One of the more controversial scientific questions of Darwin’s day was whether the different races of human beings were of the same species or not. Darwin was a long-time abolitionist who had been horrified by slavery when he first came into contact with it in Brazil while touring the world on the Beagle voyage many years before. [With the passage of The Slavery Abolition Act of 1833, Parliament had finally ended slavery throughout the British Empire.] He reasoned that most of the visual differences between the human races were superficial – issues of skin color and hair type – and that most of the mental differences were merely cases of “civilization” or a lack of it. For example, Darwin interpreted the “savage races” he saw in South America at Tierra del Fuego as evidence of a more primitive state of human civilization. He concluded that the visual differences between races were not adaptive to any significant degree, and were more likely simply caused by sexual selection – different standards of beauty and mating among different peoples – and that all of humankind was one single species. Darwin never argued nor implied that human races had been evolved at different times or stages, nor that any of the races was inferior to the others.