The Second-Order Predation Hypothesis of PleistoceneExtinctions

The end of the last Ice Age (Pleistocene) saw: 1) significant climate and vegetation changes, 2) the introduction of humans to the New World, and 3) major megafaunal extinctions. The leading theories of these extinctions - climate change and overkill - are inadequate neither explains why: 1) ruminants survived better than non-ruminants; 2) many mammal species were diminished in size; or 3) why vegetative environments shifted. Climate change does not explain why climate changes of similar magnitude did not lead to similar extinctions. Overkill links extinction with humans hunting herbivores, but omits the reciprocal impact, of prey decline on predators, yet standard predator/prey models show predators cannot hunt prey to extinction. The Second Order Predation theory handles these concerns. It holds that humans reduced predator populations, leading to a megaherbivore boom, over-consumption of plants, environmental exhaustion, and extinctions. The mathematical model developed to test this hypothesis is the only one to date that can be used to compare all three extinction theories.