primarily within species rather than between species". It is therefore inaccurate, from this point on, to refer to Darwin's theory as simply "evolution by natural selection" (Darwin himself called the theory "the principle of evolution").The primary reason why Darwin "abandoned" natural selection in favor of sexual selection was the fact that natural selection could not properly explain either the evolution of man from the animals or the differences between the sexes and races. The problem is that natural selection assumes that only beneficial changes get preserved in future generations, whereas in reality "the races of man differ from each other and from their nearest allies amongst the animals, in certain characters which are of no service to them in their ordinary habits of life". By contrast, sexual selection does not have to be useful for the purpose of adaptation to the environment, and it may actually work against natural selection. Therefore, Darwin now argued that any features that are not adaptive to the individual, and thus could not have been acquired through the process of natural selection, must have been acquired through sexual selection.When the Descent was published in 1871 it became an immediate best seller. The initial 2500 copies were sold almost instantaneously, and an additional 5000 copies were sold by the end of the year. The book was exceedingly controversial at the time, dealing with perhaps the most provocative evolutionary topic of all, the origin of man. In the book Darwin suggested that man differed from animals in degree and not kind, and than proceeded to conclude that man descended from a "hairy, tailed quadruped, probably arboreal in its habits". Surprisingly, the reaction to the book was not as violent as one might have expected it to be, from Darwin's previous experience with the Origin. For instance, Hooker, who at that time found evolution discussed everywhere relates the following: "I dined out thr...
