Strange and Alien Forms
Peter Ward: I’d like to throw out the question, is a virus alive? Lynn Margulis and I absolutely disagree about this. It comes to the point, is a parasite alive? A lot of parasites, when they’re not in their host’s body, are deader than doornails, at least by all official ideas about life. And yet they get in that host and do great. Modern taxonomy and biology have been anti-viral for a long time. In biology classes, you don’t deal with viruses because they’re not "life". So I think we have a really narrow definition. Can anyone tell me why they think a virus isn’t alive?
Carol Cleland: There’s an aspect of that question that is historically interesting, because how it was answered in the past reflects the evolution of so-called definitions of "life". At one time, people thought that life was a property of the individual solitary organism — that you didn’t need to consider its history, but rather just its properties of self-organization and self-causation. From Aristotle to Kant, people worried about teleological properties of life. Insofar as a virus doesn’t metabolize, it’s not alive in definitions like this. But with the advent of Darwinian evolution, and particularly the emphasis now on defining "life" in terms of this evolutionary process, a virus would qualify as alive.
But it’s a parasite of familiar life, so I don’t think that answering this question helps us much with the larger question about the nature of life. If we had a truly general theory of a living system, one that applied to organisms everywhere, as molecular theory gives us for water, then we could answer that question. But you’re always going to have borderline cases, and I view a virus as a borderline case of life. So in that sense I don’t find the question of whether viruses are alive terribly helpful.
Neville Woolf: Thinking of life without thinking of its environment does not make sense, because life has to get that energy out of the environment. If you want to consider fire, for example, as it approaches a life form, it’s available simply because there is a lot of oxygen in the environment, and by having dead trees you’ve got a lot of free energy around, and it’s rather easy to extract it. On the other hand, I’m sure that if you went to the P-T boundary when the oxygen was way down, it would have been much harder to extract that energy. And this is part of our problem in deciding whether viruses are alive; they’re alive because we’ve got a lot of free energy in life forms.
(former NASA Planetary Protection Officer) John Rummel: I do think astrobiology, as an inherently interdisciplinary activity, is ready for new definitions of life. I look at the panel, and we have astronomers and chemists and philosophers, and an encephalopod-guy turned into a preacher — a bunch of people who are ready to think about life in a different way. The old definition of life was really about whether we’re related to that kind of life. I would vote that we pick up stars as being living objects, because there’s no problem with that. They’re a little messy when they reproduce, and we’re made out of their parts, but that’s a kind of a nuclear family that I think we can all be part of. And it greatly simplifies the planetary protection question.
Lynn Rothschild: For those of you who don’t know, that was John Rummel, who’s probably the only one here who’s paid to protect our planet for "life as we don’t know it." I’ve been reminded that you’ve done a great job so far, John, thank you.
|Jupiter’s moon Europa is thought to be one of the most likely abodes for life in our solar system. Scientists wonder what sort of alien life forms we might find in its global ocean under the icy outer shell.|
Dirk Schulz-Makuch: I’m missing the part of the discussion, "life as we don’t know it." Do we truly have such little creativity and imagination? There have been great ideas by Feinberg and Shapiro — some were very far out, but there’re some ideas with information content by magnetic dipoles, or that you can use different types of energy sources. Steve mentioned silicon chemistry. I think we really have to look at something that is "out there," because right now we’re just thinking of our internal biochemistry processes.
Peter Ward: That’s a great point. A chemistry professor came to me and said, "I’d like to test Graham Cairns-Smith’s idea that clay particles could be alive." Clay crystals are life itself. Then he went to our group, and most of the people said, "Nah, that’s an old stupid idea." And yet it’s not a stupid idea. We are sitting here with a cellular bias about life. I do think our bar is set way too high. And I think, Dirk, you have really pointed out lots of interesting things, although I don’t like your idea about whales on Europa.
Pascal Ehrenfreund: I really admire your creativity and enjoy reading your papers, Dirk. But there is a fundamental problem when we want to look for life as we know it or life as we don’t know it. We are extremely limited. Our space missions, when we are lucky and they’re not canceled, give us a once-in-a-decade opportunity to look for something. We are not even able to miniaturize instruments from the laboratory which have the same sensitivity and send them out there. So because of budget cuts and other problems, I would say let’s be realistic. We are lucky if we have a mission with a gas chromatograph, which detects one single organic molecule — which we, for instance, haven’t detected on Mars. So this is, I think, something we have to take into account when we are looking at all of these incredible possibilities.
Lynn Rothschild: I’d like to ask a question, and maybe Steve you want to take a stab at it. What’s the chance that there is or has ever been life on Titan?
Steve Benner: Lynn, are you familiar with the male answer syndrome? That’s if you ask a man a question, he’ll give you an answer whether he knows one or not? So 28 percent. (laughs)
Jonathan Lunine has provided for me insights into water-ammonia eutectics, and the ability for there to be a large range of temperature over which water-ammonia mixtures can be fluid. It wouldn’t surprise me in the slightest if there were life in those liquid eutectics; it would not surprise me in the slightest if they were in water-oil droplets as well. Of course, I would not know how to begin to design the instrument to detect it.
Peter Ward: I really think that we can’t get around a manned mission to Mars, and I think we can not get around a manned mission to Titan. I think we need to send people there. It would be so hard – it won’t happen in our lifetimes, or our kid’s lifetimes or their kid’s, but we have to get to Titan. And at the end of my book, I’ve sent Roger Buick to Mars, and I’ve sent Steve Benner to Titan.
Steve Benner: Thanks. (laughs)
Neville Woolf: I think that we perhaps overestimate the capability of humans in highly unfavorable environments. I would think it much easier to design robotic systems to do everything that we would try to do with humans.
Peter Ward: A robotic mission could never do it.
|Shoreline on Saturn’s moon, Titan. The river channels are believed to be carved during intermittent methane rain showers. Click image for larger view. Credit: ESA|
Unidentified audience member: There’s a saying, "The eyes can only see what is in the mind." If you have a philosopher, he can only see some things, a biochemist can only see some things, an organic chemist can only see some things, and so on. So the question then is, if you take a group like that, do they see everything? I have the feeling that there’s more to life than what all these very wise people see. That’s best illustrated in the many biological phenomena that are still unexplained. I cannot talk about the origin of life, because then you get in all kinds of circular definitions. But there are also things like, how does the brain work? And if you don’t know how the brain works, then you miss an essential part of life. Other organisms are not as smart as we are, but they still have a brain. So I think that, basically, we don’t really know how life functions. And if you don’t know how life functions, you also cannot define it, and you also cannot recognize it if it is in a strange and alien form.
Pam Conrad: I’m sorry, I don’t buy that at all. That’s like saying, "If you can’t do a triple Axel, why bother to learn how to ice skate?" I would much rather live on the planet where you can be free to learn how to ice skate and assume that someday I’ll get to the triple Axel. And while there are lots of reasons to believe that we should be skeptical of our own experimental prowess and our ability to interpret a result definitively, there is absolutely NO reason not to pursue with all vigor, passion, and enthusiasm the pursuit of life everywhere on this planet and everywhere else we can get to, whether it’s robotically, or with humans.
Related Web Pages
Read Part I of this debate: "Launching the Alien Debates"
Part II: "The Dialectic Game"
Part III: "What is Life?"
Part IV: "The Basic Rules of the Universe"
Part V: "Debating Life’s Boundaries"
Part VII: "How Can We Find Alien Life?"