A mass extinction is NOT the result of extraterrestrial agents, nuclear war or disease. A mass extinction is by definition the result of a global economic collapse: the overturning of the ecological pyramid. A mass extinction occurs when the many compete for the few.The mathematicians claim that their equations enable them to predict that Man will live forever, first as posthumanists and then as ETs. The facts show something different. The socioeconomic evolution of Man has been from hunter-gathering to farming to manufacturing to services. We never crossed these bridges in the opposite direction, and there is no other major category in which to move into next. Unfortunately, Man's artificial economy is an inverted pyramid scheme. It is based on the premise that tomorrow there will be more demand (population). Instead, the population growth rate of our species is steadily decreasing. This guarantees that the Service Economy will one day suffer a fatal crisis. Once the economy collapses, the agricultural corporations have no further incentive to supply urban areas. Extinction finds the great majority of humans stranded in towns and cities without anything to eat except each other. Intelligence and forewarning cannot avert the impending economic collapse.