Francis Galton
Galton was Darwin's cousin. A man a diverse talents, he is mentioned in the book in relation to his work in genetics. He first introduced Darwin to the concept of inherited mental traits, much the same as Darwin's own conclusions about physical trait inheritance.
Alfred Russel Wallace
Wallace was a contemporary of Darwin's who arrived at the same conclusions of natural selection around the same time as Darwin.
John Lubbock and Edward Burnett Tyler
In the mid 19th century, these two anthropologists published the culmination of their work, to which Darwin makes extensive reference. They employed archaeology as a means of studying human evolution since the stone age. Unlike Darwin, Lubbock and Tyler conclude that human evolution is inevitable and defies the very will of the species.
John Bachman
A well-respected monogenist, Bachman advocated for the theory that all human races have a common ancestor. He concluded this after testing the fertility of inter-racial breeding.
