DNA Study Rules Out Bison Overkill Theory

The first humans in the Americas may be off the hook in the latest twist of a prehistoric whodunit: the crash of bison populations thousands of years ago. Proponents of the overkill theory say the first Americans hunted bison within a whisper of disappearance. Humans are also thought to have wiped out woolly mammoths, short-faced bears and North American lions.

But DNA evidence shows that climate was to blame, researchers reported in the journal Science. By the time people arrived, “these populations are already significantly in decline,” said Beth Shapiro of Oxford University, the paper’s lead author.