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  • [music]

  • [bird chirp]

  • Look down. No matter what your biological sex, I'm willing to bet most of you have

  • two nipples. If you can't see them, they're probably under your shirt.

  • Some people have even more than two! But that's for another video.

  • It's easy to see why females have two nipples.

  • We're mammals. It's right there in the name.

  • Dogs, cats, pigs and whales all have nipples too. Like us, they nourish their offspring with milk.

  • Male nipples?

  • [music]

  • Not much going on there.

  • If they're not an evolutionary advantage, why hasn't natural selection erased them?

  • Because my nipples are cheap, and they're not hurting anything.

  • In the eyes of evolution, male nipples don't have much cost: Just a little more tissue.

  • But deleting them from the recipe altogether, reprogramming the genes and body development

  • in just in one sex? That would cost more.

  • Traits don't have to provide a specific advantage to get passed on.

  • Why is your blood red and an octopus's is blue? It's not because one color's better,

  • it's just a side effect of nature selecting different chemistry for different creatures.

  • And sometimes, traits can end up being used for a function

  • different from what nature originally selected.

  • Not every trait is an adaptation, and they don't all have a point.

  • Sometimes they have two.

  • Stay Curious.

  • This video's part of our 12 Days Evolution series.

  • Check out more by exploring Darwin' beard.

  • Find the links down description or you could click that things that just pop up on screen.

  • You know what else doesn't cost much? Click and subscribe.

  • It's free actually.


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B2 US evolution cost male advantage deleting chirp

Why Do Men Have Nipples? - 12 Days of Evolution #7

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    Tiffany Yu posted on 2018/11/26
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