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  • Narrator: Lions have them, hippos have them,

  • and even you and I have them: canines.

  • Those long, pointy front teeth,

  • they're actually the longest teeth in the human mouth.

  • So what are these long, sharp teeth

  • doing among our short, stubby ones?

  • Well, contrary to popular belief,

  • it's not for tearing and ripping meat.

  • The real reason is actually much more romantic than that.

  • Human men today have 10% longer canines than women,

  • and this difference isn't unique to our species.

  • Our close relatives, gorillas, have

  • it as well to an even larger extent.

  • Males' canines are twice as long as females'.

  • That's because in gorilla society,

  • males compete for exclusive mating rights to

  • the entire female troop, and the male

  • with the longest, most intimidating

  • set of fangs usually wins.

  • Over time, gorillas have evolved increasingly longer canines,

  • but when it comes to humans, our teeth

  • took a different evolutionary path.

  • Our canines have actually become shorter over time.

  • Just look at the canines on the first human,

  • Ardipithecus ramidus,

  • or Australopithecus anamensis versus modern humans.

  • In fact, our canines today are the shortest

  • they've ever been, and the difference

  • between male and female canines

  • got less pronounced as well.

  • That's because unlike modern gorillas

  • who take after our shared ancient ancestors,

  • human men eventually stopped fighting

  • with their teeth somewhere along the way.

  • Now, scientists aren't entirely sure why this happened,

  • but one possibility is that our babies

  • grew increasingly defenseless, so males

  • had to spend more time on childcare

  • and less time on winning a mate.

  • As a result, all that's left in our mouths today

  • is the memory of a more slobbery method

  • of one-upping our peers.

  • That's right, those canines you carry

  • around today aren't particularly useful.

  • For one thing, they're not long enough

  • to grab and hold on to prey the way lions use them,

  • and they're not big enough to intimidate

  • predators' arrivals the way hippos use them.

  • Instead, they help us bite into food. That's it.

  • Turns out, evolution isn't always useful,

  • but while the truth about our canines

  • might be disappointing, those teeth

  • are still pretty amazing because

  • anthropologists use canine size and shape

  • to help track when humanlike ancestors evolved.

  • So in a way, our tiny canines make us who we are.

Narrator: Lions have them, hippos have them,

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人間が鋭い前歯を持つ本当の理由 (The Real Reason Humans Have Those Sharp Front Teeth)

  • 180 6
    April Lu に公開 2021 年 01 月 14 日
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