REWIND, ERASE, RERUN.

The article speculates a history of a hypothetical Earth in which human beings and their subsequent environmental impacts never existed. The state of the Earth 125,000 years ago is described, including a warmer climate, evolution of Homo sapiens, Homo erectus, and Neanderthal hominids, and dominance of megafauna such as whales, woolly mammoths, and bears. Various economic impacts of human population expansion are explored, including agriculture, hunting, energy use, and water consumption, as well as anthropogenic climate change. It is suggested that a modern Earth without humans would have remained a continuous biosphere in an early ice age, but some critics cite convergent evolution to argue that emergence of other hominid species would produce the same results.