J. Craig Venter, Richard Dawkins: фрагменты разговора

VENTER: Let me pick up on a point that Richard was making about the simplistic notions about Darwin and evolution. In fact, it was one of the biggest surprises for the scientific community. What we found in the environment. Most people expected just one dominant species. What we found were thousands, tens of thousands, of very closely related organisms, all basically the same linear set of genes, tremendous variation in those genes. But there was not one dominant one. There was this community of related organisms where perhaps none of them had gone extinct, or, if they had, there were literally thousands of ones to replace them. The problem we've had, I think, with looking at evolution, I think it's been overly simplified because we've always been looking at the visible world, not the absolute majority of life on this planet, which is the invisible world.
In one milliliter of sea water, there's a million bacteria and ten million viruses. In the air in this room—we've been doing the air genome project—all of you just during the course of this hour will be breathing in at least 10,000 different bacteria, and maybe 100,000 viruses. I would look closely at the person sitting next to you to see what they're exhaling.
This is the world of biology that we live in, that we don't see, where evolution takes place on a minute-to-minute basis, not on the speciations of giraffes versus elephants versus kangaroos but the tens of millions of species that constantly are affecting the metabolism of our planet. The air that we breathe comes from these organisms. The future of the planet rests in these organisms. And the question is: If we take over the design of these organisms, does that really shift the balance in any way? Or is it such a small portion of what's out there that we'll only affect industrial processes not the living planet?

DAWKINS: My vision of life is in a sense even more radical than that, because I would like to regard the genomes of the giraffes and kangaroos and humans that you refer to as just another set of viruses in close-knit societies. So the gene pool, I should say, of giraffes, or the gene pool of humans, or the gene pool of kangaroos is a huge society of viruses. I'm using the word loosely. I'm using the word "viruses" because the viruses you're talking about, the bacteria you're talking about, are kind of free spirits who are out there in the sea, and they're out there in the air. But there's another whole class of them who have, not agreed, but who have come together in gigantic clubs, gigantic societies, which is you and me. ...The whole of the biosphere is a gigantic collection of crisscrossing interacting DNA, some of which jumps from kangaroo to kangaroo, or from giraffe to giraffe, but via the normal route of reproduction, sexual reproduction, others of which jump around through the air or through the water. But it's all the same kind of stuff.

VENTER: In fact, the jumping I think is a lot further; they can jump from planet to planet. We have organisms that can withstand three million rads of radiation. They can be totally desiccated. It's been shown that they can survive easily in outer space. We exchange roughly 200 kilograms of material between Earth and Mars each year. Undoubtedly, we're exchanging these organisms. It's a question of how far they can transfer. We're starting to look at the gels from space dust to see if we can find DNA in them. These organisms, if they were shielded within a comet within any other material, the estimations that we came out of this conference could literally last tens of millions of years, find a new source of water and start replicating again. Our viruses can affect the universe just not the girl next door.
...While we worry about GMOs, primarily in Europe, I worry most about the several trillion organisms that get transferred as ballast water that they pick up in any port after they dump their cargo, take that to another part of the world, and contaminate that part of the world with all those microorganisms and viruses. This has been going on ever since ships have taken on ballast water. We are doing a cross-contamination. The experiment that Darwin did, every time a ship takes on ballast water, it moves some place else and dumps that water, they're moving billions to trillions of organisms and viruses around to create environments that wouldn't normally exist.

DAWKINS: Can I talk a bit about some of the risks? Craig, you were just talking about the sort of almost criminal contamination of oceans when tankers release ballasts of seawater, and, thereby contaminate one ocean with the organisms of another. And we're all now quite used to the idea of contamination of organisms. When you go to New Zealand, you hear thrushes and blackbirds, because the early settlers felt nostalgic for British birds, and wanted to bring British birds. I mean, it's criminal. The Duke of Bedford imported American grey squirrels into Britain, and now the red squirrel is all but extinct. We're entirely used to this idea of contamination. However, what's the equivalent that we might be doing now? What if scientists of the future are unable any longer to do serious molecular taxonomy work because the scientists of the 20th and 21st Centuries, let's say 21st and 22nd Centuries, contaminated genomes by introducing genes from other radically different parts of the living kingdoms?
It's probably all right, as long as very, very careful records are kept. However, you could imagine a situation in the future where the rather strict separation, at least in Freeman Dyson's middle stage of evolution, the sexual phase, where on the whole evolution is all divergent, there's virtually no cross-contamination of genes, if humans suddenly start cross-contaminating genes, so you have kangaroo genes in giraffes or melon genes in aardvarks, how are we going to do our molecular taxonomy? Won't it be a bit rather like people trying to study the faunas and ecology of New Zealand?

VENTER: Richard, that's the most naive question you've ever asked. And I assume you're asking it to be provocative, because in fact that's the opposite of what we see happens with evolution. Viruses move genes around from totally disparate species in a very common fashion. We have genes in our genome that resemble some, you know, from distant viruses. In fact, a third of our genome is basically viral contaminate. When we sequenced the small pox genome, the small pox genome had half a dozen clearly human-derived genes. We see bacterial genes moving in a lateral fashion from archaea to bacteria to plants to single cell eukaryotes. We do have constant information exchange across the diversity of species on this planet. I've never heard the term until this meeting, that of the "schoolboy howler", but I would put that in that category, the simplistic view of biology.

DAWKINS: Are you saying, then, that a molecular taxonomist who's trying to work out, say, the taxonomy of marsupial mammals or placental mammals would be thrown out because a bacterium or a virus has at some point carried across a kangaroo gene into a jackal genome or something ... You're not saying that. Are you?

VENTER: We're saying that we see evidence of every branch of life in almost every genome. It depends on which gene you choose, and that's been the problem with molecular taxonomy. If you choose one gene out of two or three thousand in a genome and try and classify it on that, you come up with one answer. If you pick another gene, you get a different tree. If you try and look at the genome as a whole, you get a totally different answer. So yes, we see genes moving around.
You know, the visible world and these few visible species to me are somewhat bizarre, extremes of evolution. They're not the standard. But if you look in those, in the marsupial versus, you know, a platypus genome, you would definitely find a clear cut similarity. If we sequenced another mammalian genome, we would not discover a single new gene. We would discover unique combinations that made that mammal versus us. But we have saturated the gene set for mammals. So we can pronounce and say here ... but the gene set of mammals, over half of those are shared broadly with other species. You can't draw a bright line in every gene, and say, "These are plants and these are mammals. These are humans and these are marsupials, " because we've used—it gets back to the gene-centric view. We've used those in the random design of biology, as we will use them in the very specific design that we do in the laboratory. And taxonomy is something where people sort of fool themselves by justifying what they see with their visual acuity.

DAWKINS: The overlap of mammal genes that you're talking about could come about through common ancestry. So the platypus and kangaroo genomes contain shared genes because they go back to a common ancestor. That is the normal assumption that's made by molecular taxonomists.

VENTER: Yes but once you have lateral transfer, whether it's due to viruses or anything else, the tree concept of life goes away.

DAWKINS: I think you're confusing two quite different things. I mean, of course you can make viruses and bacteria transfer things, and we know there are a few genes that have cross-contaminated from radically different parts of the animal and plant kingdoms, but I didn't know until you told me today, and I'm skeptical about it, that molecular taxonomy of, for example, mammals, is endangered by cross-contamination of genomes. I don't believe molecular taxonomists yet, at least, say, "Oh, well, we can't use this gene to get our kangaroo taxonomy right, because it's clearly been imported from a rhinoceros."

VENTER: So when we look at bacterial evolution, a typical bacteria will have 2,000 genes in it, each one of those 2,000 genes has its own separate evolutionary tree that you can construct, and none of them have the same time line that you could put together.

DAWKINS: But that's bacteria.

VENTER: But that's bacteria. So, viruses pick up bacterial genes all the time. They pick up mammalian genes all the time. A third of your genome is virus. It's not just you personally. It's, all of us have that. And there are subtle differences in those, that if a taxonomist was to measure viral genes, unmistakingly thinking it was a human gene, they would come up with a very different answer than one that was in the human lineage, perhaps from the beginning.

QUESTION: You mentioned that there's 100 trillion cells in our body, so to speak. A hundred trillion. Right. Aren't most of them non-human? Aren't we really dependent on, for our life, to have a lot of animal cells in our body? And in essence, are we not a human but a zoo?

VENTER: No. It depends on what you had for breakfast. So we have 100 trillion human cells. We have at least that many bacterial cells associated with us. So ...

QUESTION: So we are a zoo?

VENTER: Well, we're, it depends, there's not too many bacterial zoos. But an important part of human metabolism, human diet is, you're not so much what you eat, as people say, you're what you feed the bacteria in your gut. So when we look at the chemicals in the blood after a meal, there's roughly 2,500 compounds that we as a species can make. We see roughly twice that many as bacterial metabolites in our guts from what we feed them. So, we live in a bacterial milieu. We breathe it. Our guts, every orifice, our skin; we have more bacterial cells than we have human cells, and they're a very key part of our existence. We can't exist in a healthy life without them. So that could be a zoo, if you had a microscope.

DAWKINS: The questioner points out that John Brockman's Edge Website this year has a question, "When have you changed your mind and why?" And it ended up with the statement that Steven Pinker had changed his mind about whether humans had stopped evolving. I answered the question about changing my mind, and I won't give my answer because it takes too long to explain. However, I will say that in response to Craig Venter today, I am prepared to change my mind, if he gives a better answer to my question about molecular taxonomy. Maybe now is not the time to do it. But I'm on the brink of changing my mind, but I remain highly skeptical as to whether I will in fact have to do so.

VENTER: We'll have to go through some genome data as we follow up on this ... I think Pinker thought there was no human evolution because he spent so much time at a university (Laughter/Applause).

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