Ability To Consume Alcohol May Have Shaped Human Evolution

sciencehabit writes Craving a stiff drink after the holiday weekend? Your desire to consume alcohol, as well as your body's ability to break down the ethanol that makes you tipsy, dates back about 10 million years, researchers have discovered. The new finding not only helps shed light on the behavior of our primate ancestors, but also might explain why alcoholism—or even the craving for a single drink—exists in the first place.

Comments

Of course it did

[GrumpySteen]

Anyone who has woken up next to someone they hooked up with while drunk can tell you that alcohol completely undermines selective breeding.

Re:Of course it did

[sgage]

You speak as though 'selective breeding' is some sort of conscious thing where you do the selecting. Evolution has its own ideas (metaphorically - I'm not getting all teleological on you). But seriously, selectively breeding for what? Things change, selective pressures change, what's adaptive in your eyes might not be in the long run. Keep throwing the dice! ;-)

Re:Of course it did

[sconeu]

Thank you for posting that, Bruce. You don't mind if I call you Bruce to keep it simple, do you?

Re:Of course it did

[AthanasiusKircher]

Anyone who has woken up next to someone they hooked up with while drunk can tell you that alcohol completely undermines selective breeding.

Funny -- TFA actually argues that "being a cheap date" was a disadvantage and selected against:

"If you were the ancestor without this new mutation in ADH4 [to metabolize alcohol], the ethanol would quickly build up in your blood and you'd get inebriated much faster," Carrigan says. "You'd be a cheap date." This easy inebriation, he says, would have been a disadvantage to the monkeys without the mutation, making them more easily get sickâ"or drunkâ"off fruit, enough so that they couldn't defend their territory and seek out food. Primates with the new mutation could get more food, his group hypothesizes, and the gene was selected for in the human and chimpanzee lineage.

But then the next paragraph makes a 180-degree turn and claims that alcoholism evolved to be associated with pleasure because, I guess, being drunk is fun (and, apparently, tasty). So, apparently "being a cheap date" is also something that is selected FOR in evolution, or alcoholism doesn't evolve, accroding to TFA:

Carrigan says the discovery might explain why human brains evolved to link pleasure pathways with alcohol consumptionâ"ethanol was associated with a key food source. "It's not a whole lot different from the addictions some people have towards food," he explains. "At the right dose, when you didn't have alcohol and candy at every corner, it was hard to get too much of this sort of stuff, so when you found it, you wanted to be programmed to overconsume."

Argh. Wasn't it just yesterday that I was complaining about evolutionary biologists making up random "just-so" stories that conveniently show how anything could evolve?

In TFA, wanting to get drunk is bad for natural selection, until it's good for natural selection... in the freakin' next paragraph. Really, guys?

Re:Of course it did

[hawk]

Not quite.

If ethanol was lethal, it would be undesirable, and avoided. There would be an inclination away from the fermenting fruit on the ground.

For those who could digest the food that is poisonous to their competitors, a desire for such things would lead to going to consume them more often.

It's not the ones without,, but rather with the tolerance gene that would benefit from being drawn to the fermenting fruit.

hawk

Re:Of course it did

[jellomizer]

Your problem is you are missing the idea of balance.
If you get drunk too quickly, then you are open up to predation, or allowing the sick and weak to mate with you, creating weak and sick offspring.
However if you don't get enjoyment from the buzz, then you may starve due to not having a diverse food source.

Now balance isn't ying and yang or positive vs negative.
The function of benefit vs loss over consumption is not linear but much more complex.
Let's say the benefit of a buzz grows linerally, while the disadvantage grows exponetionally. You will be receiving a net benefit until you reach eqalibram. As there are point in a lineral function early on the exceed an exponential function.

Re:Of course it did

[quenda]

THEN you see an inability to process ethanol that has,

This is a bit of an urban legend. Plenty of populations have similarly reduced abilities to process alcohol, but not a big problem with alcoholism.
A better explanation is that being invaded and outnumbered by a more sophisticated race that relegates your humiliated culture to the fringes would drive anyone to drink. I'm very nervous about SETI.

Re:Of course it did

[mooingyak]

Obviously those who are able to process alcohol will get the biggest evolutionary advantage from eating food with it (as you say), but how does that lead to alcoholism unless you begin to select for people who can't control their alcohol intake and drink to excess (which is the opposite trend)?

Alcoholism isn't getting drunk easily, it's not being able to control your intake.

The article argues that alcohol tolerance made more food sources available. If this food was scarce but beneficial, a genetic craving for it would provide an advantage. It only turns into alcoholism when the source is no longer scarce, which is a (evolutionarily speaking) recent thing.

Birds Get Drunk Too, and maybe the squirrels

[Gim Tom]

I read the article and while interesting it doesn't fully explain a phenomenon I have observed first hand for many years. I have two wild cherry trees on my property and sometimes the cherries remain on the tree long enough to begin fermenting. When this happens every bird for miles fights over the boozy cherries! The squirrels also seem to prefer these somewhat fermented cherries. Humans may have evolved a better way to metabolize ethanol, but I don't think we were the first creatures to appreciate a wee dram every now and then.

Re:Birds Get Drunk Too, and maybe the squirrels

[rogoshen1]

greaaat, furnishing alcohol to these critters? You realize you're potentially liable for damages incurred due to inebriated wildlife right? You should at least start carding them.

Re:Birds Get Drunk Too, and maybe the squirrels

[kwiecmmm]

Many animals have been known to get drunk. I once saw a nature special where a lot of African animals ate the fruit off a grove of trees and all got drunk. After this happened most of them passed out next to each other. So there was an awesome site of monkeys, zebras and lions all sleeping a few feet away from each other.

I think what the article is pointing out is that our ability to process more alcohol allowed us to eat more fruit without getting drunk, which allowed us to be more mobile and defend territory better while not getting drunk. It also probably helped us defend ourselves better against predators, than those that were drunk.

Re:Birds Get Drunk Too, and maybe the squirrels

[sgage]

On the street where I grew up there was a big mulberry tree that put out huge amounts of fruit. Which inevitably dropped on the ground and fermented - just walking past it you could smell alcohol. The birds used to get snot-hanging drunk off of this stuff, especially the bluejays. You'd see them walking down the street because they just couldn't get it together enough to fly. Nothing new under the sun.

Re:Birds Get Drunk Too, and maybe the squirrels

[flyneye]

My dog got sloppy drunk, eating overripe mulberries off the ground. My wife pointed out he was staggering,aimlessly, falling, over and over. Then it hit me, I'd seen him eating some mulberries and put it together. He was a sorry dog the next day and hasn't eaten mulberries since. I notice that doesn't stop many people from repeatedly bashing their brains and organs with far too much alcohol. Hangover, vows of abstinence, shower, a short time cycle, tequila shooters or Long Island Iced Teas, silly behavior, sleep, rinse, repeat.
Dogs should be studied far closer.

Re:Birds Get Drunk Too, and maybe the squirrels

[Turmio]

Of course it's in the Internet! https://www.youtube.com/watch?...

Re:Yet this doesn't explain

[Stormy Dragon]

You don't need to cook when everything is pickled.

Re:So...

[sgage]

I'm pink, therefore I'm spam.

Re:Yet this doesn't explain

[DMUTPeregrine]

That's just due to the dilemma set up in our brains every time we try to cook: Do we cook the potato, or turn it into vodka and drink it? Do I make this wheat into bread, or beer? Add this barley to soup, or make whiskey?

I doubt it.

[Immerman]

Nonsense. I've known way too many animals, from way too many phylums, that will go to great lengths to get a good stiff drink (Or lick toads, etc.) to give any credence to the idea that the appeal of consuming mind-altering substances is tied to some human evolutionary shift.

If anything an ability to efficiently metabolize alcohol efficiently drastically reduces the effects, probably indicating that at some point in the past overripe fruit became a large portion of our ancestors diet, and the ability to "hold our liquor" gave a survival advantage whenever predators discovered the drunken tribe. Or perhaps rather than overripe fruit it's indicative of the time period when our ancestors first began intentionally fermenting things on a regular basis.