Essay Topic is Inclusive of 1–3:   (1) climate change; (2) geological upheaval & climate change in east Africa ; and (3) the theory of Natural Selection and “survival of the fittest.”  Read up on the role of the Great Rift Valley on the evolution of the hominids (see pp.249ff/Ch. 10), especially during the late Miocene (10–5.5 mya through the early Pliocene (5.5—4 mya) and throughout the Pleistocene (see pp. 279ff/Ch. 11).  Review Darwin’s idea of “natural selection” (pp.19-21) and the survival of the fittest. How does it pertain to eventual rise of our species, Homo sapiens. The terms “adaptation” and “adjustment” will be important here.