Why We Drink Alcohol Even Though We Know It’s Bad For Us

It's pretty obvious at this point that drinking alcohol — even red wine — is not great for us. But, despite knowing this, we continue to indulge. However, a new study might reveal the evolutionary basis of our drinking abilities and resulting habits. It could even make us feel a bit less guilty.

The study, published online this week in the Proceedings of the National Academy of Sciences, looked at when our evolutionary ancestors developed the enzyme necessary to digest alcohol. To do so, the researchers examined resurrected versions of the precious ADH4 enzyme (a type of alcohol dehydrogenase) along our 70-million-year timeline. And, they were able to pinpoint the moment when the genetic mutation that optimized this enzyme's functioning occurred: about 10 million years ago.

This mutation is what bumped up our ethanol-digesting powers, and the researchers say it probably happened around the same time our ancestors started eating fermented fruit from the forest floor. Being able to digest the ground fruit — despite its alcohol content — would have been advantageous, so our homininae ancestors evolved to do so. (We share these ancestors with gorillas and chimps, and had not yet diverged from them at this point.)

Because having this mutation and the resulting enzyme was so advantageous, some research has tried to link it to alcoholism. For instance, one study associated a few particular variations of the ADH4 gene with alcohol dependence in us modern humans.

As digestion of alcohol goes, humans are okay at it. We can break it down, but the process of doing so can cause us a lot of grief. In particular, it creates the toxic byproduct acetaldehyde, which has been suggested as the cause of hangovers and liver damage. So, although these new results don't necessarily show that we've been guzzling booze for many millions of years, they do suggest that, thanks to rotting fruit, we've been able to (sort of) digest alcohol for much longer than the thousands of years we've spent brewing it.

So, even if you're just a casual drinker, maybe you'll feel better about having a cocktail with brunch now that you know you're simply exercising your evolutionary advantage.