Is It Time To Throw Out 'Primordial Soup' Theory?

Ms.�JULIA CHILD (Chef): Hello, I'm Julia Child. I'm in my own kitchen today, and I'm boiling up some primordial soup.

GUY RAZ, host:

Hmm, primordial soup.

Ms.�CHILD: We're doing a recipe for the chemical building blocks of life.

(Soundbite of music)

RAZ: Well, it looks like that recipe might be changing, at least that's what Nick Lane would like to see. He's a biochemist at University College, London, and he's one of the authors of a new essay that argues life did not begin in a primordial soup of organic molecules.

Nick Lane joins us from London. Welcome to the program.

Dr.�NICK LANE (Biochemist, University College, London): Hi, thank you.

RAZ: The primordial soup theory has been around since 1929. Can you remind us what it says?

Dr. LANE: Well, it goes back to people like J.B.S. Haldane, who was one of the great biologists of the 20th century, and he proposed that the Earth's early atmosphere was composed of simple gases like methane and ammonia. And they would react together under the influence of ultraviolet rays or lightning and so on to produce a thin soup, which became thicker over time, of organic molecules, right up to simple amino acids.

But as time went by, it began to look as if there really weren't these gases in the primordial atmosphere of the Earth. There wasn't any methane, or not very much, or ammonia and so on.

RAZ: So tell us where you think life actually began.

Dr. LANE: Well, we're placing it in a particular kind of deep-sea hydrothermal vent, and we're not thinking of the famous vents belching black smoke out. We're thinking of something called alkaline vents, and they effectively percolate warm fluids up through the ocean floor. And when it when they react with the ocean waters, it precipitates out effectively into cells, into tiny cells, and it's these cells that we think are the setting for the origin of life.

This goes back, in fact, to a guy called Mike Russell(ph), who's been pioneering these ideas for some time, but it's really the energy in this setting that we have been interested in this paper.

RAZ: So for a long time, people sort of assumed that there was some kind of electrical charge that created this phenomenon. You're now saying that this may have taken place all underwater.

Dr. LANE: Yeah, I mean, there may well have been electric charges, and it may well have produced a dilute organic soup. Our point is that once you have a dilute organic soup, nothing else happens. There's nothing else to drive it, and just simply, you know, electrocuting a corpse is no good, it's not going to bring it back to life, and electrocuting an organic soup is not going to bring it to life, either.

What we've been looking for is some kind of equivalent to what goes on in modern biochemistry, the way that cells actually generate energy and the way that cells generate organic molecules today. And if you try and look at the principles that underlie it rather than all the complex details that we know about, you find that it's a very, very good fit with the kind of chemistry going on in these vents.

It's simply about the gradients across these membranes in these inorganic, primitive cells, which kind of powered life and which, in fact, still powers life today in us and in bacteria and in every form of life that we know about.

RAZ: What's an example of something that we might be more familiar with to help us get a sense of how this takes place?

Dr. LANE: Well, for example, if you imagine a reservoir behind a dam of water, the way in which the water flows through power turbines and so on, and it's the flow of water downhill through the power turbine which is generating electricity and so on, much the same thing happens in our cells except instead of having water across a dam, what you actually have in cells is protons, these hydrogen ions, and you have a difference in the concentration between one side and the other side of a membrane, and it's the driving force of these flowing through tiny protein turbines in the membrane which drives energy production in all cells today, and this is exactly the setting that we have in mind with these alkaline hydrothermal vents. You have an exactly analogous proton gradient across a membrane.

RAZ: So effectively, these cells might have copied the structures at these vents.

Dr. LANE: We think that the first cells could not have left these vents unless they had found a way of tapping into these gradients that were naturally existing there and then later on learning to generate their own.

RAZ: So is your hope that laboratory scientists will now try to test your ideas, sort of the way they did with the primordial soup theory?

Dr. LANE: Absolutely. There's a lot of gaps here. This is really an attempt to paint a larger picture and to try and focus attention on the possibility that this is the answer, but to prove that it's the answer requires quite a lot of experimental work.

RAZ: That's Nick Lane. He's a biochemist and writer based at University College, London. His team's paper appears in the journal BioEssays.

Nick Lane, thank you so much.

Dr. LANE: Thank you. Transcript provided by NPR, Copyright National Public Radio.