Penguins Lost the Ability to Taste Fish Due to a Cold Environment

Penguins may have bad taste--and that's mostly because they don't have any taste at all. Scientists have found that penguins can't enjoy or detect the savory taste of the fish that they eat. A a new genetic analysis of penguins reveals that for them, food only comes in two flavors: salty and sour.

"Penguins eat fish, so you would guess that they need the umami receptor genes, but for some reason they don't have them," said Jianzhi "George" Zhang, one of the researchers, in a news release. "These findings are surprising and puzzling, and we do not have a good explanation for them. But we do have a few ideas."

Most birds can't taste sweet things. However, birds other than penguins do have receptors for detecting bitter or umami (meaty) flavors. The fact that penguins can't taste the fish that they eat is surprising.

The researchers examined the genomes of Adelie and emperor penguins. This revealed that all penguin species lack functional genes for the receptors of sweet, umami and bitter tastes. It's possible that genes encoding these taste receptors may have been lost in penguins because of the extremely cold environments in which they live. Unlike receptors for sour and salty, the receptors required for detecting sweet, umami and bitter tastes are temperature sensitive; they don't work if they get really cold anyway. In other words, the receptors-even if penguins had them-wouldn't be of much use.

"Their behavior of swallowing food whole, and their tongue structure and function, suggest that penguins need no taste perception, although it is unclear whether these traits are a cause or a consequence of their major taste loss," said Zhang.

The findings are published in the journal Current Biology.

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