Humans Like Anything Sour After Ability To Make Vitamin C

The North Carolina State University ecologist Dr. Robert Dunn and his team have published a paper this week in the Proceedings of the Royal Society B about how and why humans evolved a preference for anything sour, Tess Joosee reported for Science.

Photo Insert: The only gene so far associated with the sour taste receptor is called OTOP1.

“We’ve lost the ability to produce vitamin C, or ascorbic acid, and liking acidic foods might be a way for us and other primate species to be reminded to ingest it. Another argument is that ancient primates ate way more fermented foods than we recognize. One way to tell if rotting fruits are safe is if they’re acidic, because the thing that makes them acidic is lactic acid bacteria and acetic acid bacteria. The acid in these bacteria kills bad new bacteria, so those fruits are almost always safe to eat,” Dunn told Joosee.

“In the last 7 million to 21 million years our ancestors evolved a souped-up version of alcohol dehydrogenase, an enzyme that metabolizes alcohol. Our faster version makes it 40 times easier to get calories from alcohol than it would be otherwise. There are also new versions of genes that have a role in recognizing lactic acid that evolve about the same time. These two fundamental evolutionary changes in our ancestors seem to match well. Based on existing data it’s likely that sour taste came first, but we don’t know for sure,” he added.

“The only gene so far associated with the sour taste receptor is called OTOP1. It’s also associated with inner-ear function, helping maintain balance, and mutations in this gene are associated with vestibular disorders. The gene for sour taste does these other things, and it’s possible losing it would have other consequences. Something as everyday as sour taste, which you can experience with every meal, still has all these really simple mysteries. It’s wonderful,” Dunn concluded.

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