Humans’ favorite pastime of drinking alcohol may also be one of their oldest. New research suggests human beings have been consuming alcohol for 10 million years. Some experts had estimated humans began imbibing libations only about 9,000 years ago. Matthew Carrigan, a paleontologist at Santa Fe College in Gainesville, Florida, led a study examining how ADH4 enzymes, which are the first alcohol-metabolizing enzymes to encounter ethanol in the body, have evolved. His team studied how the ADH4 genes have evolved and discovered a mutation 10 million years ago that enabled humans to imbibe and process alcohol. However, this change may not have occurred because our ancestors were booze-hounds, but rather because a terrestrial change caused a heavier reliance on rotting, fermenting fruit. “I suspect ethanol was a second-choice item,” said Carrigan. His findings were presented at the Proceedings of the National Academy of Science on Monday.