Acasta Asteroid Impact Can you stop thinking Lucy /Australopithecus africanus Swing A fence Letter boxes A tree.... Flower of Crab apple Poppies Calopogon tuberosus Calopogon tuberosus Darwin's study Darwin Overcrowing Trees Georges Cuvier 1769-1832 Mango, banana, Tangerine.... Figure 18.1 Humans are Strange creatures Above the clouds