By Erika Szymanski from Palate Press
In his outstanding volume The Art of Fermentation, Sandor Ellix Katz makes the disturbing proposition that rather than us having domesticated Saccharomyces cerevisiae– the yeast used to ferment wine as well as (most) beer and bread – S. cerevisiae has instead domesticated us. Katz is a fermentation wizard, the author of several books on recapturing the practice of home fermentation, and possibly fermentation’s first popular activist, not to mention one of my personal heroes. It’s fair to say that yeasts are his friends. He’s echoing a claim Michael Pollan made first, and maybe both personalities are a bit radical. Even so, this claim isn’t. Let me explain.
Humans have probably had a relationship with S. cerevisiae since cave-folk days; after all, we know that animals deliberately seek out and enjoy fermented fruit and early humans surely would have observed and adopted the trick. But drinking alcohol – or eating naturally fermented fruit – requires the machinery to break it down. Humans have that machinery: alcohol dehydrogenase first degrades ethanol into acetaldehyde, and then aldehyde dehydrogenase must degrade the also-toxic acetaldehyde into acetate, which then degrades to carbon dioxide and water. Other enzymes do help metabolize alcohol. You’ve likely heard of cytochrome p450, a secondary alcohol-processing enzyme that also detoxifies ibuprofen and is the reason why chronic heavy drinkers shouldn’t take Advil. The dehydrogenase pathway, nonetheless, is crucial.
This is a pretty specialized pathway, and it’s not the same in everyone. Some people – especially members of Chinese, Japanese, and Korean populations – have an extremely efficient version of alcohol dehydrogenase that generates lots of acetaldehyde, which then sits around waiting for the aldehyde dehydrogenase to catch up. The resulting acetaldehyde overload yields an unpleasant physical response most of us recognize: a red face, nausea, racing heart, and sweating. People who experience these effects after just one drink often avoid alcohol altogether because it’s so unpleasant. Today, that can be a disadvantage at a party. 100,000 years ago, it might have been a more significant problem for hunter-gatherers with fluctuating food sources when fermenting fruit was the plat du jour. It’s not unreasonable to imagine that cave-folk with efficient alcohol metabolizing apparatus had an advantage over those who couldn’t deal with the stuff at all (or who died finding out that drunkenness didn’t agree with them).