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2016.11.8

Penguins can only taste 2 out of 5 flavors

Today’s article is about the tasting ability of penguins. Did you know that penguins can only taste two flavors?
Find out why scientists are surprised by what they learned.

今回の記事では、ペンギンの味覚について取り上げています。ペンギンは2種類の味しか感じることが出来ないということをご存知でしたか?研究者たちを驚かせた発見について、記事を読んでみましょう。

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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.

キーフレーズ

umami うま味(日本の科学者が発見した甘味、酸味、塩味、苦味に次ぐ第5の味覚)
according to ~によれば

権威ある機関や第三者からの情報などを引用するときに使うフレーズです。

例:According to the report, profits are up this quarter.
(そのレポートによると、今期の利益は上がっています。)

while ~だが
be carried out 実施される

あることが誰かによって「行われる」という意味のフレーズです。記事内では、「その研究はミシガン大学によって実施された」という意味になります。

例:The robbery was carried out by two young men.
(強盗は2人の若い男によって実行された。)

look at  ~を調べる

記事内では、異なる種類のペンギンのDNAを「調査した」という意味で使われています。

例:Researchers looked at the effects of diet on aging.
(研究者たちは、加齢における食習慣の影響を調査した。)

sub-species 亜種(生物分類学上の単位のひとつで、種 [species] の下の階級)
savory flavor おいしい味、食欲をそそる味
puzzling 不可解な
therefore その結果

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