This is Scientific American 60 Second Science. I'm Emily Schweng.

Sex. It drives people to do crazy things.

Animals too. They'll make unsettling sounds, perform complex dances, or show off

giant plumes of colorful feathers. And famously, salmon will swim hundreds of kilometers upstream to get down to business.

They also inadvertently rework the landscape.

Adult salmon spend most of their life out in the ocean

and then they come into freshwater to mate.

Washington State University Ecologist Alex Fromier.

What the female salmon will do is she digs a hole in the stream bed.

That little hole is called a red.

That's where the salmon lays her eggs.

And for Meer says when she builds it, she basically unpacks the stream bed,

making all those loose sands and gravels more mobile.

High water and flooding events move that sediment, which in turn exposes bedrock to further

erosion.

It's quite impressive.

We did not expect to have salmon in some cases

changing the vertical position of a river channel

up to 30% more than it would have without salmon in it.

Fermere hypothesized that salmon not only influenced landscape evolution,

but that the evolution of salmon as a species itself has a landscape level impact.

To test the idea, he and colleagues recreated salmon reds in an experimental flume,

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