Bison shed light on big wipeout
New evidence casts doubt on the theory that sabre-toothed cats, mammoths and other big North American mammals were driven to extinction by human hunting. Genetic analysis of bison remains shows their populations started to crash around 37,000 years ago - long before humans arrived in the New World. Researchers claim that climate change and other factors are more likely culprits in the extinction.
See also: Climate helped wipe out large mammals (New Scientist)