Penguins can only taste two of the five flavors—sweet, sour, bitter, umami, and salty—according to research published in the journal Current Biology. Taste is important for animals because it helps them judge whether a food is safe to eat. While most birds have a limited sense of taste, it is unusual for an animal to only be able to taste two of the five flavors.

The research was carried out at the University of Michigan with help from Wuhan University in China.

Lead researcher Professor Jianzhi Zhang, now at the University of Wuhan, said penguins can only taste sour and salty foods.

The researchers looked closely at the DNA of different species of penguins. They found that the genes for umami, sweet, and bitter tastes were not working. The researchers believe these senses were lost over 23 million years ago. There are around 18-20 different species of penguin living today. All of these species have lost the ability to taste sweet, bitter, and umami flavors. So this means that the penguins must have lost their ability to taste these flavors before they split into different sub-species of penguin.

The umami taste is important for meat eating animals because it gives meat a savory flavor and helps tell the animal how healthy food is. So it is interesting that the penguin, a meat eating animal, cannot taste the umami flavor.

Zhang said: “These findings are surprising and puzzling, and we do not have a good explanation for them. But we have a few ideas.” One explanation may be that because the penguin swallows fresh fish whole, it does not really need the umami taste. Another possible reason is that the penguin developed in Antarctica where it is very cold, and the umami and bitter senses do not work well in the cold. Therefore, over time, the penguin lost these taste senses. However, no researcher really knows why penguins actually lost the ability to taste these flavors.

Now we know penguins can only taste two of the five flavors—sweet, sour, bitter, umami, and salty.

Taste is important for animals because it helps them know if a food is safe to eat. Most birds can only taste three flavors—umami, sour, and salty. But it is unusual for an animal to only taste two of the five flavors.

Researchers at the University of Michigan studied penguins with help from Wuhan University in China. They wrote about it in Current Biology.

Researcher Jianzhi Zhang was the leader of the research. He said penguins can only taste sour and salty foods.

The researchers looked closely at the DNA of different types of penguins. They realized that the DNA for umami, sweet, and bitter tastes is not working. There are around 18-20 different types of penguin. But none of these penguins can taste sweet, bitter, or umami flavors. The different types of penguins started about 23 million years ago. So researchers think the penguins lost these flavors 23 million years ago before they became different types of penguins.

The umami taste is important for meat eating animals because it tells the animal how healthy their food is. Penguins are meat eating animals, so it is interesting that they cannot taste the umami flavor.

Zhang was surprised that penguins can only taste two flavors. Zhang’s team had a few ideas about the reason why. One idea is that the penguin does not really need the umami taste because it swallows fresh fish whole. Another idea is because the penguin is from Antarctica where it is very cold. The umami and bitter tastes do not work well in the cold. Therefore, over time, the penguin lost these tastes. However, no researcher really knows why penguins lost these tastes.