Anthropogeny is the original study of human origins.
During the time of Darwin, anthropogeny was the study of human origins. Then it was taken over by its sub-discipline paleoanthropology, with focus on fossils found in dry parts of Africa.
Those fossils don't tell us much about why or where humans evolved. Humans may have evolved from chimpanzees that were isolated (chimps can't swim) on a barren new volcanic island of proto-Bioko, where they could only get food by wading in seawater.
This is the aquatic ape hypothesis, made to fit with all fossil finds, and the DNA and anatomy of humans and chimps.
Read this popular-science article in Norwegian SciTech News: Thinking outside the box of fossils
Or read this peer-reviewed paper in the scientific journal Ideas in Ecology and Evolution: A paradigm for the evolution of human features: apes trapped on barren volcanic islands.
by Allan Krill, professor of geology, NTNU. (See also AquaticApe.net)