This week, Pluto's puzzling polygons.

They look almost like biology, except their geology.

And two teams disagree on what's going on at the center of the Earth.

Is one of them wrong? Are both of them wrong? Or are they both right? And is there some really new fundamental physics that we don't

understand? Plus the genetics behind a textbook case of evolution in action. This is the nature

podcast for June the 2nd, 2016. I'm Kerry Smith. And I'm Adam Levy.

In 19th century England, a series of events transpired which would rocket the previously

unexceptional peppered moth to worldwide fame.

The moth started the century as speckled white to blend in with their favourite trees.

But then, around the middle of the 19th century, a brand new form of the moth was

spotted with completely black wings. By the end of the century, this black-winged peppered moth

had replaced the lighter-winged moths over much of England. What was going on? Many causes were

suggested, ranging from humidity to disease.

Then, in the 1890s, a naturalist named J.W. Tut put forward the idea that the darkening of the peppered moth's wings might be linked to the pollution from factories, which was turning the trees black.

Put the peppered moth with its white ground colour on a black tree trunk and what would happen? It would, as you say, be very conspicuous and would fall a prey to the first bird that spied

it out.

But some of these pepid moths have more black about them than others, and you can easily understand

that the blacker they are, the nearer they will be to the colour of the trunk of than others, and you can easily understand that the blacker they are,

the nearer they will be to the colour of the trunk of the tree, and the greater will become

the difficulty of detecting them. So it really is, the paler ones the birds eat, the darker

ones escape. We now know that Tut was more or less correct and that the Peppered Moth's appearance was changing

thanks to natural selection, helped along by the fires of industry and keen-eyed birds.

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