How has alcohol changed in 10 million years?

They’re right when they say there’s no safe level of alcohol consumption – they’re just 10 million years late.

That’s the length of time, scientists now believe, that human beings and their ancestors have been able to metabolise ethanol – the once-poisonous variety of alcohol that is contained in drinks.

Back then, climate change forced the common ancestor of humans, gorillas and chimpanzees, down from the tree canopy to the forest floor where the nutritious fruit was overripe and fermenting – laced with poison by yeasts that wanted to keep the sugary food-stuff for themselves.

Over many generations, the process of natural selection favoured apes with a genetic mutation that enabled them to metabolise the ethanol. And so, the ability to ‘booze’ became hard-wired into the human genome.

This fascinating story, known as ‘the drunken monkey hypothesis’ was told at a two-day conference staged by the British Academy in London in September, bringing together mainly anthropologists and archaeologists under the theme Alcohol and Humans: a long and social affair.

Californian biologist Robert Dudley, who came up with the drunken monkey hypothesis, set out his theory over a video link, and was supported by Matthew Carrigan, over in person from Santa Fe College, Florida, who has, remarkably, inferred our ancestral gene sequences to find the point where the evolutionary adaptation happened – 10 million years ago.

“Alcohol consumption is a nearly universal characteristic of human societies, and that suggested to me there’s a genetic disposition to drinking – an evolutionary basis,” he said.

He was also able to explain that “the toxic effects of alcohol are not from the ethanol itself”, but from acetaldehyde, a compound that can accumulate when two enzymes in the metabolic process go out of sync.

Evolutionary advantage?

Of course, simply proving the ability is in our genes tells us little or nothing about why humans have continued to drink so enthusiastically when it is no longer nutritionally necessary.

We might well, of course, have derived pleasurable sensations as well as calories from fermenting fruit. Dudley reckons that while ripe fruit might have an ABV level of 0.5% to 1%, in overripe fruit that might rise to a heady 8%.

Carrigan speculated there might even be evolutionary advantages in being a bit tipsy by reducing inhibitions and escaping self-awareness.

But is that enough to explain why we graduated from picking up naturally fermented fruit to going to the immense effort of brewing our own beverages to ensure a reliable effect?

The recent discovery of 13,000-year-old beer at a burial site in Israel provides a clue that these first brews coincided with the origins of social drinking – and one of the most dramatic developments in human history, the agricultural revolution.

Not only did Neolithic tribes begin growing the grain to make beer, what were previously hunter-gatherer societies started living together in the first human settlements.

One of these, unearthed by archaeologists at Gobekli Tepi in what is now Turkey, shows evidence of large feasts that attracted people from as far away as 200km – to what would appear to be an early food-led destination venue.

Bringing people together

What might be brewing equipment and decorated drinking vessels have been found on the site, reported Oliver Dietrich from Germany’s Archaeological Institute.

“Feasting was at the centre of co-operative work alongside rituals with mind-altering substances that generate cohesion and affirm a group identity,” he said.

Drinking rituals helped ease the potential conflict inherent in the novel business of living in close proximity to a lot of other humans and helped bind together these early communities.

Alcohol, as anthropologist Michael Dietler of the University of Chicago explained, became charged with meanings and purposes beyond mere calorific nutrition and played a key role in defining a group identity.

“So it’s not reducible to a chemical substance with psychoactive effects. It’s symbolic and a social tool with implications throughout society.

“Drink helps to create social relationships and identities, it actually constructs a social world.”

In sharp contrast to today, when drinking is positively excluded from the workplace in developed countries, for pre-capitalist societies it “mobilised labour, making work a festive event”.

And, as anthropologists at the conference pointed out, that’s still the case for some communities in the developing world.

But even in a modern society where work and play are strictly segregated, a beer or two can play a positive role in oiling the cogs of friendship and, in the right circumstances, improve our health prospects.

Oxford-based psychologist Robin Dunbar tied together the importance of social drinking for humans past and present by pointing to research his team carried out for the Campaign for Real Ale (CAMRA), brought together in the 2016 report Friends on Tap.

A survey among more than 2,000 adults showed those using a local pub had more friends and scored higher on a range of positive factors.

In turn, “friendships have the biggest impact on survival,” said Dunbar, quoting research among patients recovering from a heart attack in which ‘network quality’ was shown to increase the chances of survival. Only giving up smoking was more effective. 

The feel-good factor

The roots of this effect are found among our primate relatives where “endorphins released by grooming create a psycho-pharmacological environment for building trust”.

But humans don’t have time for grooming, and our social groups are too large. On average, we spend only 20% of our waking lives interacting socially. So we “bridge the gap with story-telling, dancing and laughter, all of which trigger the same endorphin response”.

Recent research has demonstrated that alcohol, too, releases feel-good endorphins that, in the company of others, reinforce the pleasures of bonding.

This works especially well, Dunbar argued, in smaller community pubs, which score higher on the happiness scale because regulars have longer conversations, usually over a beer, the drink arguably best suited to those slow, low-tempo situations.

All of which is not to deny that alcohol, or rather acetaldehyde, is potentially a danger to health. It’s significant, though, that lone drinking is stigmatised in most, if not all, societies, and when we look back at our history we can see how deeply drinking practices are embedded in the social life and wellbeing of communities.

As James Nicholls of Alcohol Research UK, closing the conference with a summary of modern debates on the drink question, said: “We don’t talk enough about pleasure when it comes to understanding alcohol harms.”