19 July 2011
Greetings from scenic Timmins Ontario!
I will be spending the next 9 days with a bunch of geologists, biologists, chemists, planetary scientists, and all around smart people, learning about the geology of the Abitibi Greenstone Belt near Timmins. In particular, we will be talking a lot about the origin of life, and how this chunk of ancient crust on Earth can (or cannot) be used as an analog for Mars and other planets.
I spent most of the time on my flights up here frantically reading the literature assigned as background for what we are talking about on the trip, and I think I can safely say that my knowledge about the origin of life has already been fundamentally changed. You’ve probably heard of the theory of the primordial soup, where life arises from a concoction of various prebiotic chemicals at random, right? Yeah, turns out that’s wrong. The latest theories instead point to a series of energetically favored reactions in alkaline hydrothermal systems that build on each other to produce increasingly complex organic molecules. In this hypothesis, the metabolism comes first, and RNA and DNA appear later as life gets more sophisticated. This is quite different from the RNA-world hypothesis which suggests that fragments of RNA in the primordial soup gained the ability to self-replicate.
It turns out there is quite a heated debate between the RNA world view and the “metabolism first” view, and I had the awesome chance to see it play out first-hand. At dinner last night, one of the people at my table was Michael Russel, who happened to be the author of one of the fascinating papers I had read earlier in the day advocating the “metabolism first” theory. He was extremely passionate and articulate about the subject, and ended up sitting next to an advocate of the RNA-first theory. Russel made the excellent point that if you’re starting with a primordial soup, you already have a high-entropy situation, so it’s very difficult to have the molecules of life (i.e. RNA) spontaneously form. If instead you’re starting off with hydrogen and CO2 and some minerals, it is much easier to get started. Essentially he said that biology has led us all the way down to RNA, but that’s where a lot of people have gotten stuck. Now, he argues, you have to start from basic chemistry and thermodynamics and work your way up to meet the biologists at RNA.
Anyway, this promises to be a fascinating week or so. I’m surrounded by people who are way smarter than me, so I will be in sponge-mode all the time, and I’m going to do my best to blog it if I have time. Stay tuned!