TOKYO: Penguins are among the world’s most dedicated seafood eaters. But they can’t taste fish, biologists discovered.
Chinese and American researchers have found that the flightless birds have only two of the five basic tastes — salty and sour — after losing the capacity to detect sweet, bitter and “umami” or savoury flavours.
Jianzhi Zhang, a genomic evolutionist at the University of Michigan, said the results were surprising. “Penguins eat fish, so you would guess they need the umami receptor genes,” he said.
The discovery, revealed in the journal Current Biology, adds to the taste limitations known to bedevil some of the world’s most loved and loathed creatures. “Whales and dolphins have lost all tastes except salty,” Professor Zhang told The Australian. “Vampire bats have lost sweet and umami tastes.”
Birds also lack receptors for sweet flavours, even though many eat fruit and nectar. Scientists believe birds lost the T1R2 gene — which is crucial for tasting sugar — sometime during or after their evolution from meat-eating dinosaurs.
The latest study found that receptors for detecting bitter and savoury tastes were also missing from the genomes of Adelie and emperor penguins. Subsequent research revealed the other 15 penguin species also lacked these genes.
The researchers believe another key gene, known as TRPM5, may have effectively been frozen out of the genome of living penguins’ most recent common ancestor during an evolutionary stint in Antarctica. TRPM5 is “temperature-sensitive” and doesn’t function properly when things “get really cold”, the journal reported.
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