Humans and Booze: A 9,000 Year Old Love Affair

Happy Hour has been with us for a very long time now, in fact, all around the world, evidence for alcohol production from different kinds of crops is showing up and some of them, dating to near the dawn of civilisation. People cannot deny that alcohol consumption has been part of the human life longer than previously thought.

According to University of Pennsylvania Biomolecular archaeologist Patrick McGovern, alcohol consumption was not an accident. From the Stone Age rituals, he argues that the mind-altering properties of alcohol have fired human’s creativity and promoted the development of language, arts, technology and religion. If you look closely at many great transitions in human history, from the invention of farming to the origin of writing, there’s a possible link to alcohol.

McGovern also stated that 30 years ago, that fact was not recognised and accepted as it is now. He also added that drinking is such an integral part of community and humanity as a whole.

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Evidence of alcoholic drinks goes back at least 9,000 years, where Chinese jars were discovered having traces of ethanol from grains and fruits. Even before that, primate ancestors were attracted to fermented fruit for its good qualities like calories, easy digestion and the good feeling it gave them. Many historians once considered alcohol as just another consumable, but it’s becoming clearer that alcohol was one of the driving forces behind many significant developments in human history.

Yes, we drink alcohol because we like it and makes us feel better if consumed within one’s limits, but are there any deeper reasons or evolutionary explanations as to why our body and brain is so responsive to alcohol?

Actually, there is a theory about alcohol consumption and the human attraction to booze. It’s called the “Drunken Monkey Hypothesis” and this theory proposes that our attraction to alcoholic drinks derives from a powerful sensory bias that associates alcohol with nutritional rewards. Primates evolved as fruit eaters in many tropical rainforests, where yeasts are abundant and fermentation happens quickly because of the warm and wet climate. A ripe fruit in the forest is hard to fight, but the smell of alcohol will lead you to the source. And once located and consumed, alcohol can stimulate feeding, just as it does in modern humans through the aperitif effect. Physiologist Robert Dudley of the University of California, Berkeley was the first to suggest the idea.

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He said that the primates that went down the trees got access to a brand-new food source. He said that the ones that went down defeated the competition and got more of the needed calories. The ones that stuffed themselves with the very ripe and pulpy fruits were the most likely to succeed at reproduction and to experience a mild rush of pleasure in the brain. This buzz reinforced the appeal to modern humans and made alcohol and eventually brewing a part of society and different civilisations.

The psychoactive effects of alcohol, as contained within the sugar-rich pulp of fruit may have evolved to let hungry primates find and consume limited calories in the rain forest. Other scientists also believe that this is the part of our ancestral sensory and behavioural development that is retained into the modern times. It also has been proven that there are health benefits of low-level alcohol consumption as compared to high-levels of drinking.

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To narrow down the timeline between 80 million years to 9,000 years and to be more specific, researchers have focused on the genetic evolution of the enzyme ADH4. This enzyme had been present in primates in various forms for at least 70 million now and is the first to encounter ethanol after it is consumed.

With the help of genetic sequences from 28 mammals, 17 of them were primates, the researchers worked backwards to create a family tree for ADH4. The researchers synthesised 9 different ADH44 proteins, they tested each one for their ethanol-metabolising properties.

Almost all of the ADH4s from the test primates were not able to metabolise ethanol, but about 10 million years ago, something dramatic happened. It led to a single amino-acid alteration in the enzyme that rendered ADH4 40 times more effective at breaking down ethanol than before.

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The evolved ADH4 came around a time when the ability to break down alcohol would be advantageous, like when our human ancestors turned to ground-level food sources. Environmental changes could also have put pressure to earlier primates to transition from forest ecosystems to the grasslands.

As modern humans, we know that when we have access to large amounts of cheap and high concentrated booze, things can go wrong. There is a mismatch between what our ancestors ate and what modern humans can brew and create today through agriculture, controlled fermentation and distillation to get strong ethanols. By separating liquid alcohol from the fermenting fruits and grains, people can get high levels of psychoactive reward while drinking can sometimes result in too much consumption. And with too much alcohol consumption, obesity and diabetes can be fueled by the unlimited access to cheap alcohol.

It can be said that alcoholism can be informally thought of as a long road to an evolutionary hangover, so drink moderately.


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