Charles Darwin on human evolution

In the Origin of Species, Charles Darwin says little about human evolution, other than to assert firmly that we humans did evolve and are part of the interrelated natural world along with all other organisms. However this should not conceal Darwin's great interest in the topic, a matter to which he turned in his Descent of Man (published 12 years after the Origin), where he made very clear the natural processes leading to Homo sapiens, dwelling at length on the special role of the secondary mechanism of sexual selection. In the Descent, Darwin makes it very clear that he thinks human thinking and actions, especially in the moral realm, have an evolutionary origin just as much as our physical nature.