This is scientific American's 60 second science.

I'm Christopher in Tagyatta.

Fossilized skulls and skeletons found in European caves

gave us our first glimpse of our ancient cousins the Neanderthals, and a finger bone found

in a Siberian cave first indicated the existence of another relative, the Denisovans.

But fossils are hard to come by. So here's another option.

Analyze cave floors to see if they contain any DNA. We find ancient hominins,

we find Neanderthal mitochondrial DNA and the nesillin

mitochondrial DNA. Vivian Sloane, a geneticist at the Max Planck Institute in

Germany. She and her team found that molecular evidence by testing teaspoon

fulls of sediment from seven different caves.

And they screen specifically for mitochondrial DNA because there's a lot more copies of it

in cells compared to nucleus DNA, which has just one set per cell. The researchers uncovered genetic

evidence of Denisovans where you might expect, at Denisova Cave in Siberia, which showed that

their strategy was sound.

They found Neanderthal DNA there too, and at three of the other seven caves,

including a cave where no Neanderthal fossils have ever been found,

only artifacts and animal bones.

And they found the DNA of some surprise guests too.

For example, the woolly mammoth or the woolly rhino,

we have cave hyenas and cave bears.

The study is in the journal Science. know we have cave hyenas and cave fairs.

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