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National Institutes of Health
Ancient birds traded umami for sweet, leading to today's hummingbirds
Ancient birds traded umami for sweet, leading to today's hummingbirds

Hummingbirds don't have teeth, and yet they have quite a sweet tooth. They eat insects to get such essentials as protein and fat, but most of their diet consists of sugary nectar. This has puzzled scientists. Humans and other animals who prefer sweet tastes are able to recognize them thanks to a pair of sensory receptors known as TIR2 and TIR3. But birds don’t have the gene that codes for TIR2. How, then, do hummingbirds know that nectar and sugar water are sweet? Now, an international team of biologists and their colleagues think they have found the answer: Over millions of years, genetic mutations converted a receptor that used to help hummingbird ancestors detect the savory...

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