Human Ancestors Were Consuming Alcohol 10 Million Years Ago

By Carl Engelking | December 1, 2014 3:24 pm


The holidays are packed with opportunities to raise a glass of our favorite boozy beverages and toast family, friends and good fortunes. But our ability to digest rum-spiked eggnog may be due to a massive climate shift that occurred millions of years ago.

Using the tools of paleogenetics, scientists have recently traced the evolutionary history of an enzyme that helps us metabolize ethanol, the principal type of alcohol found in adult beverages. Scientists believe early human ancestors evolved their ethanol-digesting ability about 10 million years ago to fortify their diet as they shifted from a tree-based lifestyle to a more ground-based lifestyle.

Ancestral Alcohol

Researchers were hoping to shed light on when, exactly, human ancestors acquired the ability to consume foods containing ethanol, such as fermented fruits. Attempts to answer this question have yielded wildly divergent theories. One theory holds that primates regularly ingested ethanol some 80 million years ago as plants started producing fleshy fruits that could drop and ferment on the ground. Other scientists believe humans started enjoying ethanol just 9,000 years ago when we learned how to ferment foodstuffs.

To help narrow that range, researchers studied the genetic evolution of alcohol-metabolizing enzyme ADH4, which has been present in primates, in one form or another, for at least 70 million years. Using genetic sequences from 28 different mammals, including 17 primates, the researchers were able to work backward and create a sort of family tree for ADH4.

To see how the past versions would have worked, researchers then synthesized nine different ADH4 proteins and tested their ethanol-busting properties.

Nearly all of the ADH4 enzymes from our primate ancestors were inactive — meaning they didn’t break down ethanol. However, about 10 million years ago, when orangutans and human ancestors diverged, things changed dramatically. A single amino acid alteration made ADH4 able to metabolize ethanol 40 times better than before.

Turning Point

This genetic switch to alcohol tolerance occurred at roughly the same time as apes moved from the trees to the ground. A period of rapid environmental change was putting pressure on ancient species, as forest ecosystems transitioned to grasslands.

The timing leads researchers to suspect that an ability to digest alcohol was a benefit for our ancestors, who had to find ground-level food sources. Fallen fruit that began to ferment and produce ethanol could be poisonous to primates that couldn’t digest it. Therefore, our ability to metabolize ethanol, researchers say, may trace back to our ancestors’ taste for fermented foods. The results appear today in Proceedings of the National Academy of Sciences.

There’s still more to learn — metabolizing ethanol is a complicated process involving an orchestra of enzymes. ADH4 is just one component of the process. Researchers would like to study the evolution of other ethanol-metabolizing enzymes to paint a more complete picture of humans’ relationship with the intoxicating substance.

But one thing seems clear — this holiday season we’ll be partaking in a very ancient tradition indeed.


Photo credit: /Shutterstock

CATEGORIZED UNDER: Health & Medicine, Living World
  • Jon Lisle-Summers

    So, now we know – our ancestors stopped living in trees because alcohol made the ground go round and round.

    • George Meladze

      Yeah, it must be difficult to live in the trees when you are under influence.

  • MisterKay

    Sounds like someone managed to figure out how to research alcohol at uni!

  • weddingringstayson

    Genesis 9:19-21King James Version (KJV)

    19 These are the three sons of Noah: and of them was the whole earth overspread.

    20 And Noah began to be an husbandman, and he planted a vineyard:

    21 And he drank of the wine, and was drunken; and he was uncovered within his tent.

    So we know that people drank alcohol after the Flood. I don’t believe there is a reference before that.

  • johncoryat

    Anyone who’s lived in the country and has had apple trees knows that the wild critters love to get drunk on rotting fruit. Many times I’ve seen a dozen dear staggering around at dawn, like the end of some raucous cocktail party that only ends when the booze runs out. I’m sure a thinking creature would wonder why and try to find out. No big surprise there.

  • Jack D. Ripper

    I’m pretty sure they tried mushrooms first….

    • darkhours

      Or many of the other of mother nature’s pharmacological treasures. Oh, I miss the days when I could partake of ‘shrooms. Today I’m almost 60 and I so much want to once again return to the places that I visited back when I was 14 and 15. Wonderful places that I truly hope that I can see once again before my time is up. Oh well…

      • Zinovi Golodner

        I am almost 80 now and never used narks. Sometimes I think “did I miss something that others enjoyed?” Well, too late now, I don’t think I could handle those pleasures.

  • Ettina

    So, that means you could share a beer with a chimp or a gorilla, but sharing a beer with an orangutan might kill them…

    • Guadalupe Lavaca

      That’s why I stopped going out with Orangutans. I had to take a taxi home.

  • quadrill

    Yep, elephants get totally blitzed on rotting mango fruit in a yearly party! They can actually fall down they get so drunk, and an elephant falling down isn’t good, for the elephant or anything in its way!
    This is a good magazine, but it does tend to mislead part of the time. It seems that drawing conclusions is the sole purpose of some scientists and a LOT of regular folks. Maybe the focus should be toward absorbing information and not being so critical just because one never heard of something and it happens to run contrary to what they think they already ‘know’. I read about a condition recently called ‘auto brewery syndrome’ aka ‘gut fermentation syndrome’ and I won’t go into the details, you can do that yourself, but after you do try to tell someone else about what you have read about this ‘rare’ condition and they will probably tell you that you are nuts for even bothering wasting your time! Well when the ‘man’ puts you in jail because they never heard of something so it cant possibly be valid you will find you will have plenty of time to read all the crappy books you can get your hands on , in jail!
    Merry Christmas everyone and Cheers!

    • AmIJustAPessimistOrWhat?

      A majority of tree climbing elephants are tea-totalers by necessity.

      • Zinovi Golodner

        That’s hilarious!

  • KitchenFairy61 .

    So what about Asians who can’t drink because it makes them feel sick? Or Native Americans that can’t digest alcohol? I’m of European decent and I lack the enzyme to digest alcohol. It makes my face bright red, I feel flushed and nauseous with my first sip. I avoid alcohol because of the way it makes me feel.

  • Dexter Brown

    That’s not a news. It is natural.

  • Zinovi Golodner

    Now we know, it’s the orangutans that are at fault, they developed the enzyme that makes us metabolize and crave alcohol.

  • Guest

    Perhaps human ancestors got so drunk they never could return to the trees again, drunken Tarzan does not live for long. Banished from the trees by CUI’s (climbing while intoxicated) humans began the long stumbling march “forward” to the destruction of their own environment


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