A common mistake about Charles Darwin is that he implied that humans descended from monkeys. His seminal work is entitled On the Origin of Species by which he meant “on how the biological phenomenon of species (variations in types) occurs—why there are species—he was not talking about “Man” as a species. The further work of such scientists as Sir Julian Huxley and Jean-Baptiste Lamarck led eventually to the concept of evolutionary “trees”—that is, dendritic taxonomies, and one speculation is that homo sapiens is in the same “tree” (but not the same “branch”) as other primates. (Chimpanzees, for example, have 23 pairs of chromosomes while humans have 24, so there are obvious differences.) In modern times, Richard Leakey questions the theory.