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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 narwhals tusks.

The tusks, 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 tests.

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 tusksize 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 a disproportionate growth.

We call that hyperallometry.

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 tuft is disproportionately long.

And then we also see that there's intense variation.

...