Human ancestors may have begun evolving the knack for consuming alcohol about 10 million years ago, long before modern humans began brewing booze, researchers say.
The ability to break down alcohol likely helped
human ancestors make the most out of rotting, fermented fruit that fell onto the forest floor, the researchers said. Therefore, knowing when this ability developed could help researchers figure out when these human ancestors began moving to life on the ground, as opposed to mostly in trees, as earlier human ancestors had lived.
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To learn more about how human ancestors evolved the ability to break down alcohol, scientists focused on the genes that code for a group of digestive enzymes called the ADH4 family. ADH4 enzymes are found in the stomach, throat and tongue of primates, and are the first alcohol-metabolizing enzymes to encounter ethanol after it is imbibed.
The researchers investigated the ADH4 genes from 28 different mammals, including 17 primates. They collected the sequences of these genes from either genetic databanks or well-preserved tissue samples...
One model for the evolution of alcohol consumption suggests that ethanol only entered the human diet after people began to store extra food, potentially after the advent of agriculture, and that humans subsequently developed ways to intentionally direct the fermentation of food about 9,000 years ago. Therefore, the theory goes,
alcoholism as a disease resulted because the human genome has not had enough time to fully adapt to alcohol.