Reactions to On the Origin of Species one hundred million years." Copies of the second edition were advertised as ready on 24 December, in advance of official publication on 7 January 1860. The "Saturday Review" of 24 December 1859 strongly criticised the methodology of Darwin's calculations. On 3 January 1860, Darwin wrote to Hooker about it: "Some of the remarks about the lapse of years are very good, & the Reviewer gives me some good & well deserved raps,—confound it I am sorry to confess the truth. But it does not at all concern main argument." A day later, he said to Lyell "You saw I suppose
On the Origin of Species these variations: I might have adduced for this same purpose the differences between the races of man, which are so strongly marked; I may add that some little light can apparently be thrown on the origin of these differences, chiefly through sexual selection of a particular kind, but without here entering on copious details my reasoning would appear frivolous. Chapter VII (of the first edition) addresses the evolution of instincts. His examples included two he had investigated experimentally: slave-making ants and the construction of hexagonal cells by honey bees. Darwin noted that some species of slave-making ants were more dependent