Life's Building Blocks May Have Been Ice Cubes
JACKI LYDEN, host:
When you think about the primordial soup from which the first life supposedly crawled, well soup is supposed to be warm, right? But there's increasing evidence that life may have begun in ice.
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LYDEN: This week in Science Out of the Box, the experiments of the late Stanley Miller, who was the first scientist to suggest that the building blocks of life could form in the tiny pockets of liquid water that exist within ice.
Dr. Jeffrey Bada was a student of Dr. Miller's, and he joins me on the line now from California.
Hello, Dr. Bada.
Dr. JEFFREY BADA (Professor, Marine Chemistry, Scripps Institution of Oceanography, University of California, San Diego): Hello. Nice to be with you.
LYDEN: Would you please tell us about your work with Dr. Miller? I understand that he kept a vial of ammonia and cyanide at 100 degrees below zero Fahrenheit for 25 years. What were you looking for in that vial?
Dr. BADA: Well, Stanley was interested in how the organic compounds we consider necessary for the origin of life could've been formed on the early earth and elsewhere. We know that one of the potential reagents that could be involved in the synthesis of these building blocks is ammonium cyanide.
Now, if you put ammonium cyanide in water, as we think it might have been in the oceans of the early Earth, it would be very dilute, and that formation of those compounds would be very slow.
Stanley had the foresight to think about well, what about if you froze this solution of ammonium cyanide, and what happens when you freeze something like this is that you have little pockets of liquid water that remain in the ice way below the temperature of freezing, and these little pockets end up concentrating all of the salts, and including ammonium cyanide.
LYDEN: Now, what gave him the idea that life might have begun in ice?
Dr. BADA: Well, we know one thing about this period of Earth's history. This is some four-plus billion years ago. The sun was a lot dimmer than it is today, and this generates what's called a faint young sun problem. Without a lot of greenhouse gases in the atmosphere, the surface temperature of the earth would've been below the freezing point of water, and so you have very rapidly under these conditions a totally ice-ball earth.
LYDEN: So you've got the ammonium cyanide in this little glass vial, which he studied, I guess, every day for 25 years.
Dr. BADA: Now, Stanley never really looked at this. He just put it in a big -what's called the DuraFlask, which is like a Thermos bottle, and he and I were having dinner one night, and he just casually mentioned this experiment, and all of a sudden I went, my God, how long has it been sitting there? And he said well, it'll be 25 years. And I said well, that seems about the right length of time to open it up. Let's see what it looks like.
And when we pulled the little vial out of the Thermos, we immediately noticed it was brown, and we knew immediately that signified chemistry had taken place.
LYDEN: So what was that chemistry that took place? What did you call it?
Dr. BADA: Well it - in chemical terms, it's called polymerization. That means you take a simple molecule and make a complex molecule made of many parts. And so the cyanide had reacted with itself to form a polymer, and we know that one of the products of that is amino acids, which are the building blocks of proteins, and so even under these cold conditions, the solution was so concentrated that the simple molecules interacted to form more complex molecules.
LYDEN: So by putting ammonium and cyanide in a vial and letting it sit for a quarter of a century, you actually recreated the building blocks of life?
Dr. BADA: That's correct.
LYDEN: Dr. Jeffrey Bada is a professor of marine chemistry at the Scripps Institution of Oceanography at U.C. San Diego. Thank you very much for speaking with us, Dr. Bada.
Dr. BADA: Oh, it's a pleasure.
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