Not only is beer a delicious frothy mixture of alcoholic goodness, but some scientists think it may have played a pivotal role in the shaping of the history of humankind.

There's evidence that grain convinced our nomadic hunter-gatherer ancestors to settle down and build civilizations centered around agriculture.

It seems natural to conclude they used that grain to make bread — a diet staple used around the world today. But there's evidence that our ancestors were more interested in growing grain to make beer, not bread.

(Come on, which one would you choose?)

Beer over bread

Fermentation — the magic process that turns sugars into alcohol — happens naturally. All you need is a little yeast.

So our ancestors certainly came across naturally fermented fruits and grains in the wild, but the moment when humans realized they could harness this power is unclear.

The earliest chemical evidence of barley-based beer dates back to 3500 BC, but some scientists think grain-based beer has been around much, much longer. Excavations have revealed potential ancient beer-brewing tools, and experiments have shown that you can make a low alcohol content drink with a simple mortar and pestle.

Early brews were likely not quite as strong as the ones we know today, but they would have produced the same kind of feel-good buzz. And once that relaxing effect became clear, it's easy to imagine humans wanted to make more of it.

As Jeffrey Khan, a clinical associate professor of psychiatry at New York-Presbyterian Hospital, argues, beer may have been exactly what we needed to suppress our desperate hunter-gatherer extincts to survive. It gave us time to relax, and awakened the desire to experiment, to invent, and to create art — all characteristics of flourishing civilizations.

And indeed we see evidence of beer in very early civilizations. Our ancestors made beer the centerpiece of religious ceremonies, used it heavily in celebrations that encouraged social bonding, buried their dead with it, and even used it as a form of currency in some areas.

And humans may have had more reasons to turn to beer before bread. Patrick McGovern, an archaeologist at the University of Pennsylvania, argues that beer is more nutritious than bread, and safer to drink than water since fermentation kills off pathogens.

beerREUTERS/Jason Lee

Of course not everyone subscribes to the idea that beer domesticated us. Other archaeologists and historians point out how grain is easy to store and keeps for a long time. They say its reliability as a food source is what convinced humans to settle down and raise crops.

But there are puzzling inconsistencies. Studies in Mexico suggest that teosinte (an ancient form of maize) was much better suited for brewing beer than it was for making corn flower or bread tortillas. It took a long time for farmers to turn the grains into a more maize-like crop that could be used as the food staple it is today. So some think it must have been used for beer first.

Whichever came first, beer or bread, one thing is clear: Alcohol played a very important role in early civilizations.