Scientists don’t really know, it turns out. The prevailing thought for a long time now has been that our ancestors used our mouths’ powers of bitter detection to keep from munching on possibly toxic plants, back when we weren’t thinking about which craft beers to sample but were more focused on gathering food to survive.
But now other science types are saying that might not be the case, reports NPR’s The Salt blog. Our bitter abilities first popped up about a million years ago after a twitch in our ancestors’ DNA gave them the ability to perceive a bitter compound in things like olives, nuts and seeds, the scientists note in the journal Molecular Biology Evolution.
That happened way before modern humans showed up to order bitter beers or add bitters to drinks, but the reason probably isn’t what we thought.
When the authors of the study analyzed taste genes across indigenous groups still practicing ancient ways of living, like hunter-gatherers and nomadic herders, those gatherers didn’t have any extraordinary bitter taste skills or special gene sequences compared to the pastoralists.
“We thought we’d see a difference in the bitter genes between the hunter-gatherers and pastoralists because of their diet,” the study’s author tells The Salt. “But there was no correlation all.”
The researchers found that the ability to perceive bitter flavors varied by geography, but it had nothing to do with how they got their food.
If it’s not for the sake of our survival that we can taste bitter flavors, then why are we tasting it all? No one is sure, the study’s author says.
“These genes could be detecting a compound we don’t know anything about,” she says. And because bitter taste receptors are also in cells in our guts, lungs and even testes (oh and also the bitter tears I cry over Aaron Rodgers’ collarbone), maybe they aren’t even supposed to be involved with tasting food.
“So the receptors are not only altering how we perceive food,” she says, “but probably also our physiology, in ways we have no idea about.”