And the Hello, welcome to the naked scientist with me, Chris Smith and also with

Ginny Smith. This week mass extinction.

250 million years ago, nearly all life on earth ended.

Back from the brink, history then repeated itself with the disappearance of the dinosaurs 60 million years ago.

Are we next?

Let's hope not, but we'll find out in the news this week how a Comet Smash could have

kick-started life on Earth, are East Cigcigarette safe, and why science and medical reporting in the media

might be untrustworthy.

The Naked Scientists Podcast is powered by UKfast.co. UK.

One of the biggest unanswered questions in science is how life began on earth. One theory is that

primitive chemicals develop the ability to copy themselves and eventually

evolve to encase themselves inside bubbles, effectively becoming cells. And 4 billion years of

evolution later, here we are. But where did those chemicals, which scientists think were

early forms of the genetic letters or bases that make up our DNA

come from in the first place.

Well this week researchers have quite literally shed some light on the question by using a laser to

recreate the conditions of a time when the early earth was being brutally

battered by droves of incoming asteroids and comets during a phase called the late

heavy bombardment. The energy in these collisions

they've shown could have driven the chemical reactions that created DNA-like

molecules, as science writer Mark Peplo explains. A team of researchers from the Czech Republic has found that impacts

from asteroids or comets billions of years ago could have created some of the key molecules necessary for life.

...