This chapter narrates how A.R. Wallace, Charles Lyell, and Thomas Huxley disagreed with Charles Darwin on the question of whether the human being is different in kind from our closest animal ancestors or merely different in degree. Siding with the first three, it is explained how difference in kind in evolution can be created not only by genetic mutation, but also by behavioral innovation. Jean Baptiste Lamarck's important contribution is discussed, and it is explained how the concept of the econiche easily unites Lamarck's notion of behavior as an evolutionary force with Darwin's and Wallace's notion of evolution by natural selection.