SCOTT: Good afternoon. I hope you have been as informed as I have been by these various topics and the people who have spoken so eloquently about their own contributions to the very central areas of concern in the field of evolution. We certainly have gone very widely across several scientific fields: geology, physics, biology, anthropology. I know that you have many questions and that, the panel was stimulated by each other's presentations as well. Does anyone here at the front table wish to comment on anybody else's paper first?
SCOTT: I have a question for Stan. I was very struck in your presentation. It seems to me that when we look at the history of the origin of life, that we don't have what I think many people think of, we don't have a "ta-da," boom, there's the first replicating molecule. From the way you were describing it, it sounds like we really have a continuum. We have chemicals that are just sort of there and are generated in large quantities by many different possibilities. You mentioned all the different sources of energy that are available. We have some chemicals that appear to have some slight enzymatic potential replicating ability but we wouldn't really want to call this life exactly. And then a little bit later on we have stuff that looks like it's really replicating. This is pretty neat but it doesn't have a membrane on it yet and then a little later on we have stuff that actually has a membrane. It seems to be a continuum rather than a single line in the sand that we can say "ah-ha", we have life, and on this side we don't. Maybe what would be useful would be to define life. Unless it's a continuum and you can't. You want to take a crack at this?
AWRAMIK: If you look at how Webster's dictionary defines life, I forget exactly what it says but it's unsatisfactory. Life would be, for some reason, I think it's Sydney Fox's comment, it's notoriously difficult to find. I don't mean that as a cop out but what life is, is some kind of metabolizing, reproducing organism, involving energy transformations and is the simplest way there. Getting back to your first part of the question, I guess in many ways one thing that I walk away with when I think about the origins of life, I tend to use the plural, origins of life, rather than origin of life. Not because I'm saying that life probably originated on other planets in the universe, but that I think there's a good possibility that life originated several times on this planet. It may be that the processes involved in producing some kind of membrane enclosed, or at least some localized chemical body that could take in substances, involve energy, to transform things and reproduce, could happen locally. In other words, in a pond, at a vent system under the ocean, on rocks exposed to solar radiation, in thermal springs, and things like that. So, I sort of don't look at it as here you cross the line, but I think there was a line that was crossed and that would be the last common ancestor. Because all life can be traced back to a last common ancestor, it could have evolved and most likely evolved several times. Probably in the earliest phase of that appearance one of the hypothesis is that first life was very simple and a fermenter and utilized all the organic materials in that primordial soup as a food substance. As those organisms grew and reproduced, their rate of consumption was much greater than the rate of production of the organic materials and then you wind up running into a supply/demand bottleneck.
So there were probably waxing and waning of populations against the backdrop of possibly depending on raw material availability and things like that for chemical evolution against the backdrop of relatively even production or somewhat, possibly variable production of material. That could go back and forth and maybe life sort of just ate itself out of existence at an early time until you could get to some kind of autotrophy where it could actually produce its own substance using some kind of external energy source. That was probably the major breakthrough that would allow life to completely, not completely, but in many ways move away from its original environment dependant on organic materials