Beth Shapiro

But it was really the idea.

What really helped this field along was the invention of PCR.

It's an acronym for polymerase chain reaction.

It's a way of Kerry Mullis, who discovered the idea of PCR while he was high on a road trip.

Yeah.

We should all do LSD, I think, because clearly you have your best ideas when you're high.

Yeah, I think I probably would not have good ideas on LSD, but I'm willing to give it a shot.

A good scientist always wants to know.

Probably not.

You never know.

Anyway, he discovered a way to photocopy DNA to make lots of copies of the same thing, which then made it possible to learn the sequence using the technologies of the day.

And that was what made it possible really for ancient DNA to take off, was this ability to photocopy.

When an animal dies or plant dies, the DNA in the cell starts to get chopped up into smaller and smaller pieces by things like UV, right?

We go out in the sun, we put sunscreen on, and that stops the UV from breaking our DNA.

But it's not terrible to get some sunlight, as you probably just saw.

There was an article out saying, hey, dummies, we need some sunlight in order to make vitamin D. But we have a repair mechanism so that when your DNA breaks, it doesn't stay that way.

We evolved this mechanism.

But once you're dead...

You no longer have the energy for that to work.

And so these damaged parts of DNA accumulate.