Birds Lost Their Sweet Tooth, Hummingbirds Got Theirs Back

In 2004, the chicken became the first bird to have its genome fully sequenced. Its’ DNA revealed something odd—or rather, an odd lack of something. It was missing a gene called T1R2, which we and other mammals need to taste sweet foods. Chickens, it seemed, can’t taste sweets.

They aren’t alone. Maude Baldwin from Harvard University and Yasuka Toda from the University of Tokyo looked at the genomes of 10 different birds, from falcons to finches and ducks to doves. None of them had T1R2. Alligators do, and they’re some of the closest living relatives of birds. So at some point, as birds evolved from small dinosaurs, ...

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