What is the motivation that pushed humanity towards agriculture? This is one of the great questions of anthropology. In the 1950s, bread was thought to be that catalyst, but an American botanist named Jonathan Sawyer challenged this assumption and suggested beer. To date, this debate has not yet been closed.
Archaeological evidence Recent studies indicate that humans were already making beer as early as 13,000 BC, when agriculture had not yet been introduced. We also know that the first agricultural communities settled in Israel, along the Black Sea and indeed in China They made wine and beer. What is clear is that humans have always loved fermented beverages.
In fact, our evolutionary history with alcohol goes back to the time when we were hairy apes. Let's place ourselves in a lush tropical forest, where the environment is warm and humid. When its fruits ripen, intense competition begins to obtain the precious sugar they contain. This includes carnivores, but also microorganisms. Specifically, yeasts have developed a strategy to eliminate their competitors: through fermentation, they convert sugar into ethanol, which is harmful to bacteria.
Now let's think about the little monkeys that jump from tree to tree in search of food. For them, the ethanol released by ripe fruit is a very valuable clue to finding it. It is possible that natural selection has acted on carnivores to associate alcohol with food reward. Therefore, it is likely that alcohol is a common component of the diet of many primates. These ideas proposed by Robert Dudley in An article published in 2000known as the “drunken monkey hypothesis”, currently exists He has a lot of evidence. We know that wild primates consume fermented fruits and that they are very sensitive to the smell of ethanol. It has also been shown that carnivorous mammals do not recognize this substance as toxic, and there is a relationship between the amount of alcohol a species consumes and its genetic ability to metabolize it.
Oddly enough, humans and other great apes are better adapted to consuming alcohol than other primates. Multiple pathways are involved in the metabolism of this substance, which usually begins with the action of alcohol dehydrogenase (ADH). There are many versions of this enzyme, each specialized for a different type of alcohol. One is ADH4, which is very effective in metabolizing geraniol, an alcohol produced by plants in the leaves, but is ineffective with ethanol.
About 10 million years ago, A mutation appeared in ADH4 This allowed ethanol to be oxidized approximately forty times better than before. It happened in a common ancestor between humans and African great apes. In fact, chimpanzees' taste for alcohol is also known. In Guinea, locals harvest fermented palm sap. They puncture trees and place plastic containers to collect the sap that flows throughout the night. The chimpanzees have learned the trick and love it Drink sap from bucketsWhich contains 3% alcohol.
This behavior is unnatural, because chimps normally don't have access to this sap, but it shows how much our closest relatives tend to drink alcohol. Because these chimpanzees weigh less than a human on average, they can sometimes become intoxicated.
There are also some other primates that have the same mutation, such as the aye-aye, where they evolved independently. It and the slow loris feed on fermented palm nectar with a high alcohol content, but show no signs of poisoning. Study published in 2016 He showed that both species can distinguish between drinks containing different degrees of alcohol and that they prefer the stronger one.
Thanks to a single amino acid change in ADH4, aye-aye can exploit valuable nutritional resources. It may also have given our ancestors an evolutionary advantage in a past environment and time.
Let's travel back about 24 million years, until the early Miocene, the golden age of primate evolution. During this time the first monkeys appeared in East Africa. They live in the trees of tropical forests and feed mainly on fruit. They diversified rapidly, and by 17 million years ago, there were at least 14 different genera. At the same time, sea levels dropped due to global cooling and many ape species migrated from Africa to Eurasia.
For the species that remained in Africa, the climate was still warm and humid enough to produce fruit year-round, but in Europe the cold was more severe and the habitat changed to deciduous forests with open grasslands. The availability of fruit declined in the winter months and the monkeys began to starve. As the teeth suggest that have been found from this time.
About 8 million years ago, there were no ape species in Europe. Some of them became extinct and others migrated. Those that went to Asia gave rise to the orangutan lineage, and those that returned to Africa preceded gorillas, chimpanzees, and humans.
These monkeys who returned to Africa had adapted to spending more time on the ground, where they could find fallen fruits from trees and other types of food such as tubers and roots. Moreover, they found East Africa very different from the one their ancestors had left behind, where volcanic activity in the rift valley had favored a shift towards the savanna habitat, where our bipedal ancestors evolved.
During this period, the ADH4 mutation occurred. This is why we share the ability to metabolize alcohol better with chimpanzees and gorillas, but not with orangutans. This helped our survival by allowing us to eat the highly fermented fruit we found on land without getting poisoned.
However, what was an advantage 10 million years ago, need not be the case now, as is the case with sugar. The strong attraction we feel towards sugar has ended up turning against us, and in today's societies, where we can eat as much as we want, diseases such as diabetes and obesity abound.
Something similar can happen with alcohol. Controlled doses of this substance, like those we find in the natural environment, shouldn't be harmful, but now we have high-alcohol drinks at our fingertips. according to Some scholarsThe greater ability of our ancestors to metabolize and use ethanol from fermented fruit millions of years ago may favor higher rates of alcoholism today.
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