BBC Sounds, Music, Radio, Podcasts.

Ellen Garland is perched on the deck of a small research vessel,

floating on the high seas of the eastern Pacific Ocean just off the coast of Australia.

Sunlight pierces the gentle waves, casting dappled rays onto the speckled skin

of a solitary giant. Hanging off the side of the boat, Ellen's right ear is flat to the water

surface. She's listening out for the unearthly call of a humpback whale.

I don't exactly know why, but I've always wanted to study whales.

And I was just captivated, absolutely captivated by these majestic creatures.

Ellen closes her eyes and focuses,

because of course, she's not just listening for pleasure.

Back then, in the early 2000s,

she was a young PhD student,

working alongside some of the most celebrated whale researchers in the world,

and she couldn't believe her luck.

Sometimes they sing so loud that the sound will actually come up into the air around you.

And so to actually see these animals singing, I was off for a massive adventure.

I'm Hannah Fry, a mathematician who studies patterns in human behaviour,

and from BBC Radio 4, this is uncharted.

Tales of data and discovery.

Around 34 million years ago, a group of whales evolved a new way of eating.

Rather than catching creatures and cutting them with

their teeth, these whales would filter vast volumes of food through their mouths. At some point,

...