Understanding the human body is a team effort. That's where the Yachtel group comes in.

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This is Scientific Americans' 60-second Science. I'm Jason Goldman.

Deep beneath the frozen surface of the Arctic swims a sea unicorn.

In reality, it's a whale with a spiral tusk sprouting from its head, the narwhal.

Biologists have long debated the purpose of male narwhal's tusks.

The tusk, like those of elephants, are actually elongated teeth.

And since narwhals are usually below the sea ice, it's tough to see how they use their tusks.

It turns out we don't know pretty much anything about them because they're impossible to study really in the wild.

Arizona State University Evolutionary Biology graduate student Zachary Graham.

He wondered if the male's tusks were a sign of status as a potential reproductive partner.

Comparing tusk size to the whale's overall body size could provide evidence.

One of the main trends that has been documented in over 100 different animals and 100 different

traits is that there's disproportional growth.

We call that hyperalometry.

And all that means is that the sexual trait is growing disproportionately compared to the

rest of the body.

So it's not like the biggest narwhal is just a scaled-up version of a baby narwhal.

What we see is that the tusk is disproportionately long.

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