Last year, we learned that whales can only taste one of the five primary tastes: salt. Now, scientists have discovered that penguins only have two of the five.
Sweet, sour, salty, bitter, and umami (savory) are the five primary tastes. Not only do those tastes help animals discover what they do and do not like, they actually help protect animals from consuming potentially poisonous food. New research reveals that penguins lost three of the five – sweet, bitter, and umami – more than 20 million years ago and never regained them.
“Penguins eat fish, so you would guess that they need the umami receptor genes, but for some reason they don’t have them,” study leader Jianzhi “George” Zhang, a professor in the University of Michigan Department of Ecology and Evolutionary Biology, explained in a news release. “These findings are surprising and puzzling, and we do not have a good explanation for them. But we have a few ideas.”
Zhangs current hypothesis is that penguins lost those genes during climate-cooling events in Antarctica. It’s possible that cold Antarctic temperatures interfered with taste perception and penguins never regained those senses.
Previous studies have shown that all birds examined to date lack the sweet taste receptor, but penguins lack two more. None of the five penguin species studied have the ability to taste sweet, umami, or bitter. Penguins separated from tubenose seabirds around 60 million years ago, and the major penguin groups separate from each other around 23 million years ago.
“Taken together, our results strongly suggest that the umami and bitter tastes were lost in the common ancestor of all penguins, whereas the sweet taste was lost earlier,” the authors wrote.
To learn more:
- Read the news release: Sweet, bitter, savory: penguins lack three of the five basic tastes.
- Read the study abstract: Molecular evidence for the loss of three basic tastes in penguins.
Copyright © 2015 by Marine Science Today, a publication of Marine Science Today LLC.