Coming up, the gene editing technique that doesn't seem to actually edit genes.

It's basically snowballing into a huge ball of skepticism now.

And Pluto scientists figure out what that big white spot is with very little data.

This is amazing. I am so impressed. Plus, a study of mitochondrial replacement in human cells

shows that some faulty DNA can stick around. This is the Nature podcast for December 1st,

2016. I'm Noah Baker. And I'm Adam Levy.

Back in July 2015, NASA's New Horizon spacecraft sent back the most detailed images ever taken of Pluto, along with a wodge of juicy data.

Much to the internet's delight, one of the surprises that came back was that

dear little Pluto has a big heart, or rather a large heart-shaped formation spanning around

1,000 kilometres of Pluto's surface, but that's less fun to say. This month, in a set of four

papers published in nature, scientists are getting to the bottom of what the heart actually is,

and what it might mean for everyone's favourite little dwarf planet. One intriguing theory is that

it's a big bowl of nitrogen ice concealing a subsurface ocean. I called up Amy Barmlinear from the

Planetary Science Institute in Tucson, Arizona. She's written a news and views article about all the

papers, and she started by telling me what scientists first thought they were looking at when they saw

Pluto's heart. They had no idea. I think the first reaction that people had was actually emotional.

You know, the New Horizons mission had been on the chopping block several times. And I think that people had sort of a latent fear that we would get to Pluto

and it would be boring. And so when they saw that feature on Pluto, they knew that they had found

something interesting. They knew that Pluto had been active and that something had happened there.

And I think everybody was thrilled.

And now with this data from New Horizons, scientists are actually getting to grips of what the heart is.

Tell us, what is it made of?

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