A University of Michigan-led study of penguin genetics has concluded that the flightless aquatic birds lost three of the five basic vertebrate tastes – sweet, bitter and the savory, meaty taste known as umami – more than 20 million years ago and never regained them.

Because penguins are fish eaters, the loss of the umami taste is especially perplexing, said study leader Jianzhi "George" Zhang, a professor in the U-M Department of Ecology and Evolutionary Biology.

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

Zhang suspects the sensory changes are tied to ancient climate-cooling events in Antarctica, where penguins originated. His leading hypothesis is that the genes were lost after cold Antarctic temperatures interfered with taste perception.

A paper on the topic by Zhang and two Chinese colleagues is scheduled for online publication Feb. 16 in the journal Current Biology. The first author, Huabin Zhao, was a U-M postdoctoral researcher under Zhang when most of the study was conducted.

Read the full Michigan News press release

The study is receiving widespread media coverage, including the following: NPR, BBC, New Scientist, Discovery News, the Los Angeles Times, and many more.

Listen to a short and fun NPR interview with Zhang.