Scientists think that our species, Homo sapiens, emerged about 100,000 years ago somewhere in Africa. Imagine that back at the time, scientists in another galaxy had been searching the cosmos for life and discovered our solar system and Earth. So they park their spaceship above the Rift Valley in Africa and gaze at the vast expanse of lush forests, plains teeming with wildebeest, zebras, elephants and gazelles and rivers filled with hippos, crocs and flamingoes. Those extragalactic scientists would no doubt notice small family groups of a two-legged, upright, furless ape but I doubt that anyone would point to them...