Until now, scientists believed that the alcohol was first brewed by Neolithic villagers in Jiahu, China. Neolithic villagers were believed to have discovered that fruits could be fermented into liquor. But a new study reveals that human ancestors began drinking alcohol more than 10 million years ago. Findings of the study were published in the journal Proceedings of the National Academy of Sciences.
ADH4 genes produce the necessary enzyme
The study was conducted by a team of researchers, led by Prof Matthew Carrigan, at Santa Fe College. Scientists believe that when human ancestors left the trees and shifted to a terrestrial lifestyle, they began scooping up fermented fruits that fell on the forest floor. But how did their bodies learn to digest ethanol, which is present in rotting fruit?
To figure it out, scientists studied the ADH4 gene that produces an enzyme to break down alcohol. They argued that the enzyme wouldn’t have been produced until early humans started consuming alcohol. They were surprised to find that the ADH4 gene mutated to start producing enzyme responsible for ethanol break-down about 10 million years ago. The ADH4 enzymes are present in the throat, tongue and stomach of primate.
A genetic mutation gave primates ability to metabolize alcohol
Carrigan and his colleagues investigated ADH4 genes from 28 mammals, including 17 primates. They collected gene sequences from well-preserved tissue samples or public database. And then they studied how the ADH4 genes evolved over time. Researchers inserted these genes into bacteria, which manufactured the ADH4 enzymes, to test how effective those genes were at breaking down ethanol and other alcohols.
The results indicated that a single mutation about 10 million years ago gave primates an enhanced ability to break down ethanol. That timing coincided with humans adopting a terrestrial lifestyle. The findings also help explain why humans, gorillas and chimps can metabolize alcohol, but tree-dwelling orangutans can’t. Fruit lying on the forest floor has much higher concentrations of ethanol and fermenting yeast than those hanging on trees.