About 10 million years ago, the primate lineage from which humans come was already drinking alcohol , specifically when one of the enzymes that metabolizes ethanol in fruits was activated.
According to a paleogenetics study led by Santa Fe College (New Mexico) biologist Matthew Carrigan, this “serendipity” took place in the days when the common ancestor of humans, gorillas and chimpanzees came down from the trees. Thanks to the fallen fruit , which tends to rot, those first hominoids that walked on the ground – perhaps doing that – found sustenance and food.
When the fruit is past, one point more than ripe, it can contain as much ethanol, the natural alcohol of plant origin, as beer. A few years ago, the American researcher Robert Dudley studied the alcoholic composition of the fruit of a type of palm typical of the American jungles and found that it reached 8%. That led him to argue with other paleoanthropologists that there is a connection between the evolution of hominids and alcohol consumption , contrary to the most accepted theory according to which this substance did not enter the diet until about 9,000 years ago, when the sedentarism and agriculture spread at the same time in various parts of the world.
The accumulation of grain and fruits allowed early Neolithic men to preserve them through fermentation and their subsequent transformation into alcoholic beverages. Alcoholism would be, from this point of view, the dark side of a gap between an environmental change (the technology of fermentation) and human genetics, which was not prepared to assimilate alcohol.
But Carrigan’s team’s research takes the emergence of alcohol much further back than the emergence of alcohol, in fact before humans existed . After analyzing in current and extinct primates the evolution of class IV alcohol dehydrogenase (ADH4), one of the enzymes that metabolize the different alcohols that enter the body, these experts estimate that the enzyme was activated about 10 million years ago.
At that time, a mutation in one of the hundreds of amino acids that make up the enzyme allowed the common ancestor of human gorillas and chimpanzees to metabolize ethanol . On the other hand, orangutans, which unlike the other great primates have not stopped being arboreal, do not present this modified enzyme. In fact, the activation of ADH4 would have occurred shortly after the lineages of the orangutans and that of the other three groups separated.
This relationship between ADH4, the metabolization of alcohol in fruits, and the lowering of trees leads Carrigan and his colleagues to suggest that the enzyme change was an adaptive advantage for humans and their ancestors .
