
For a dentist, the narwhal’s smile is a mystery of evolution (2012) - sohkamyung
https://insider.si.edu/2012/04/for-dentist-the-narwhals-smile-is-a-mystery-of-evolution/
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chubot
I'm no biologist... but the person quoted in the article doesn't seem to
understand that some things are explained by natural selection and some things
are explained by sexual selection. The tusk doesn't have to have a purpose.

 _“The whole thing that is great about the teeth of the narwhal is that
nothing makes sense,” Nweeia adds. “The tusks are an extreme example of dental
asymmetry. They exhibit uncharacteristic dimorphic or sexual expressions since
females do not exhibit erupted tusks as commonly as males. Also, the tusk has
a straight axis and a spiraled morphology. Conventional mechanisms of
evolution do not help explain these expressions of teeth.”_

From Wikipedia:

[https://en.wikipedia.org/wiki/Sexual_selection](https://en.wikipedia.org/wiki/Sexual_selection)

 _Sexual selection can, typically, lead males to extreme efforts to
demonstrate their fitness to be chosen by females, producing sexual dimorphism
in secondary sexual characteristics, such as the ornate plumage of birds such
as birds of paradise and peafowl, or the antlers of deer, or the manes of
lions, caused by a positive feedback mechanism known as a Fisherian runaway,
where the passing-on of the desire for a trait in one sex is as important as
having the trait in the other sex in producing the runaway effect._

[https://en.wikipedia.org/wiki/Fisherian_runaway](https://en.wikipedia.org/wiki/Fisherian_runaway)

As another example, musical talent is probably an example of "Fisherian
runaway" in humans. It doesn't make a person more likely to survive, but it
makes a person more likely to mate.

The key point is that music can be broadcast to a large audience. And the
audience can instantly tell if the music is "good" or not. It can't be faked.

You make patterns of noise that indicate 1) working sensory perception 2)
motor skills 3) cognitive skills like memory and 4) the ability to cooperate
with other humans (i.e. a band).

Hence it indicates fitness. It's selected for sexually, but not "naturally".

(edit: Now that I google it, it seems like a lot of scientists think that too
(including Darwin), which is not surprising. It seems hard to prove, even
though it makes a lot of sense.)

~~~
solipsism
Eh.. you're going to have to provide something other than a constructed "just
so" story to get anyone to believe that musical talent has been specifically
selected for. It's not impossible, but it's not at all obvious either.

~~~
TheOtherHobbes
Humans are moderately complex, so we have multiple means of demonstrating
fitness rather than just one. But there's plenty of evidence that _successful_
public music performance is highly attractive to at least some of the
population. (Noodling around with a DAW in your spare bedroom doesn't count.)

I vividly remember reading a site in India which explained how expertise in
one particular style of drumming was "considered useful in marital selection."

In the 18th and 19th centuries, musical skill could literally be a deal maker
for eligible women looking for a husband.

And groupies are definitely a thing - certainly once you get to the stadium
sell-out and/or internationally known DJ level.

It's even rumoured that killing a karaoke session will get you admiring looks.

(Etc.)

~~~
foldr
The fact that a trait is sexually attractive isn't good evidence that it's
present as a result of sexual selection.

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gumby
> The strap-toothed whale, for example, has two teeth that wrap over its upper
> jaw preventing the animal from opening its mouth.

A weird animal I'd never heard of until reading this article!

~~~
d--b
Just saw this too! Amazing!

------
inlined
> They exhibit uncharacteristic dimorphic or sexual expressions since females
> do not exhibit erupted tusks as commonly as males.

Sexual dimorphism is common in the ocean (at least with fish). Is dimorphism
unheard of in mammals (eg whales)?

~~~
Woberto
I wonder if they meant with regard to teeth, since I assume for mammals that
use teeth the way we do dimorphism would be less common or less extreme

~~~
inlined
Random but fun tangent: browse through some of the identification books by
Paul Humann. Many fish have different traits in their juvenile, adult, and
sometimes terminal phases (e.g. the spotted drumfish is breathtaking in JP and
much less in AP). They can also change color. Memorizing these fish for scuba
diving sometimes feels like prepping for the LSAT.

