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  • [ Sound of apes ]

  • >> When the food gets tough ...

  • the tough get chewing ...

  • and often with teeth adapted through evolution to handle the demanding cuisine.

  • That's the finding of scientists from George Washington University and the National Institute of Standards and Technology

  • who report that different types of apes use these special teeth to chew foods

  • that become the fare when their usual staples are scarce.

  • >> Chimpanzees, gorillas, and orangutans all prefer the same foods, and these foods are soft ripe fruits.

  • But they don't actually have similar tooth morphology.

  • They have some significant differences in their teeth.

  • Based on observations in the wild, we had some ideas as to why this might be, but we really had to come to NIST

  • and do some experiments here to gather the data necessary to support those ideas.

  • >> For chimps, gorillas and orangutans ...

  • the usual daily menu means fruit.

  • But sometimes fruit is in short supply ...

  • and that's when apes have to look for what scientists call "fallback foods."

  • Gorillas go for leaves and tree bark ...

  • while orangutans opt for nuts and seeds.

  • Chimpanzees simply hit the road to gather the fruit they can't find at home.

  • Constantino and his team of anthropologists hypothesized that gorillas have evolved broader back teeth for the purpose

  • of chewing leaves and bark, which are soft but fibery tough.

  • Orangutans ...

  • on the other hand ...

  • would have developed molars with thicker enamel to withstand the stress of crunching hard seeds.

  • >> It makes sense if you think about it because when times are hard, that's when your survival tools are most important.

  • If you don't have the teeth that are able to chew through your fallback foods, then you're not going to be able to survive

  • until a period when you can get those easier-to-access foods.

  • And if you can't survive through that period, then you obviously can't pass on your genes to the next generation.

  • >> To test these ideas ...

  • the GWU researchers asked James Lee, a NIST materials expert, for help.

  • >> In our laboratory, we perform fracture experiments on human teeth, and from these experiments,

  • we develop models that can be applied to other animals.

  • We thought this technique could shed some light on how primate teeth may have formed.

  • >> The NIST data support the GWU hypothesis that apes developed their special teeth for fallback foods.

  • In addition ...

  • the researchers say they may have evidence showing that fallback foods have influenced the form of ape jaws and skulls.

  • And their results could have important implications for the apes of today.

  • >> [Sound of apes] So, if humanity is serious about protecting apes, and conserving them,

  • then we need to protect not only the fruit trees that these animals rely on for most of the year, but also the fallback foods

  • that they rely when times are particularly tough.

  • Our research shows just how important and influential these fallback foods are.

  • Apes have evolved over millions of years the tools needed to access these foods,

  • but they still have to be able to find these foods in the first place.

  • [Silence]

[ Sound of apes ]

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B1 中級

猿の口から出てきた歯は進化のヒントを与えてくれる (Out of the Mouths of Apes: Teeth Provide Insight on Evolution)

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    QAM Chen に公開 2021 年 01 月 14 日
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