The Curiosity rover recently discovered methane on Mars, which may indicate the presence of life forms there. Does this mean we are on the verge of discovering life on Mars? Biology and genetics professor Gary Ravkan wants to look for DNA on Mars. He is attracted by the idea that life as we know it is universal throughout the Milky Way.
For almost seven years, NASA's Curiosity rover has been exploring the surface of Mars. Two weeks ago, he made a startling discovery with relatively large concentrations of methane gas. The rover also detected methane in 2013, but the concentration recorded this month - about 21 billionths of a fraction - was tripled. The reason this message became big news in the scientific community is because methane is often a sign of life; despite the fact that this gas can be the result of various chemical reactions, a significant part of it is produced by living things. Does this mean that we are on the verge of discovering life on Mars and, if so, what kind of life it could be?
To discuss these issues, I spoke on the phone with Gary Ruvkun, a molecular biologist and professor of genetics at Harvard Medical School. Ravkan, as he himself admits, takes an unusual position in the question of the origin of life and the possibility of detecting signs of life anywhere. In short, he questions the conventional assertion that our DNA-based lifeform originated on Earth. The interview, which began with a conversation about the discovery of methane, turned into a discussion about why he wants to send a device to Mars called a DNA sequencer. (After our conversation, NASA announced that the methane concentration had dropped to normal levels, causing scientists to be even more confused.) During our conversation, which has been edited and abridged for clarity,We also discussed how the scientific debate about the origins of life intersects with religious debate, the reasons why he can be fatally wrong, and what it means to express a minority opinion in the scientific community.
What is the main conclusion you made from the fact of methane detection?
- Searching for methane is a good technique for indirectly searching for life. The problem is that there are also chemical methods for producing methane. It cannot be called an ideal surrogate for life. Therefore, NASA's proposed experiments to detect life, especially in our era of exoplanets, when so many planets were discovered around stars, are aimed at spectroscopic studies of their atmosphere. This is always associated with the use of large quantities of chemicals such as methane and CO2.
Do you think this is the best way to accomplish this task? Or do you think there is a better way to do this research?
“This is the only way to conduct them in such remote places. My favorite way to find life is to fly to the planet and look for DNA there. It follows that life on another planet may be completely analogous to life here, but most astrobiologists represent the state of affairs somewhat differently.
How does your point of view on this issue differ from the generally accepted one?
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- In my opinion, the thesis that life originated here is somewhat presumptuous. Based on it, it seems that we are somehow completely unique, and that everything happened exactly here. I am aesthetically attracted to the idea that life as we know it is universal throughout the Milky Way. It seems that as soon as it evolves, it begins to spread. And one way to prove this is to run the clock forward, not backward. If we're really talking about colonizing Mars, the first step is to send bacteria there to form an atmosphere. So if you start the clock a million years ahead, presumably we will be sending bacteria to different planets a million light years away.
So, wait, I just want to understand it. So you say you find it romantic or attractive to think that other life forms will be comparable to us?
- Yes. The fact that life did not originate here. She just landed on our planet. That it originated somewhere else. And many people complain about this. They say, "Well, you just transfer the problem of the origin of life to another place." And so it is.
In your e-mail you described your views as “not very standard in the field of microbiology”. And this is partly due to the fact that you want to send a DNA sequencer to Mars, right?
- Here on Earth, if you go somewhere to the lake and want to know who lives there, then the following method is used to find the answer to this question: dirt is taken, DNA analysis is carried out and all genomic compounds within this DNA are determined. This gives you a pretty good snapshot of who exists in that place. Of course, there are many different types of bacteria that live in soils and similar substances.
And, if you look in the literature, there are tens of thousands of studies that are based on this, and the first time this was done, in my opinion, 20 years ago, then DNA was used as a fingerprint to detect existing organisms. And we can say, "You can just do the same on Mars and analyze the DNA sequence." And then you would ask: "Well, is there someone there like our cousin?" What we find should not be our brother. It can be connected with us by more distant ties than a brother, for example, as a cousin, which means that it can come from the same life tree. Once you've done that, you can say, "Well, life on Earth and Mars are similar, and that's kind of the least interesting idea, because Earth and Mars are very close." So it's almost obviousthat they may have the same form of life, because there is an exchange. But what if there is one and the same life form all over the Milky Way?
What would people who are skeptical about your thoughts say in response to this?
“They would say that is nonsense. [Laughs] Because they say, “Well, it had to start somewhere, so why don't you think it started here? Why do you put forward the hypothesis that we have taken up life, and not become the source of its development? " Because there is clear evidence for the development of life in our genomes. This is called the RNA World, which was the earliest form of life and is still present in our genomes. We can see it there, so we can identify the early stages of evolution with just one analysis of modern genomes. In textbooks and in orthodox science, the RNA World - a kind of precursor to the DNA world - was on Earth four billion years ago. And I would suggest that, no, it probably existed ten billion years ago somewhere on the other side of the Milky Way and spread throughout the galaxy.
It turns out that for any of the hypotheses - neither about four billion years, nor about ten billion years - there is no scientific justification? Is that what you mean?
- No no no. The earth has existed for 4.5 billion years. And the universe, at least if you count from the Big Bang, is about 14 billion years old. Therefore, if life originated somewhere else, you have a time reserve of ten billion years. But I would prefer that this reserve be a hundred billion years or a thousand billion years. It would be much nicer.
And why would it be so much nicer?
- Well, because that way you have more time. Do you see, the point is that if you look at the fossil record, where can you find the first evidence of life? Of course, you will find evidence for bacteria, what looks like bacteria, what are called stromatolites, these greenish-bluish bacteria that exist in colonies. These all form good fossils and can be seen 3.5 billion years ago. That is, life has already evolved to the stage of the formation of rather complex bacteria very quickly after the cooling of the Earth.
And, you know, most people outside the scientific community will say, "Well, yeah, bacteria are pretty simple organisms." But bacteria are not simple organisms. Bacteria are incredibly complex. Bacteria are the self-replicating robots that electrical engineers dream of. They can create a copy of themselves in 20 minutes with four thousand parts.
So, well, what conclusion can be drawn from your story about bacteria?
“They were at an incredibly high level of evolution, and I think they got here as soon as the Earth cooled down and just started growing. They spread throughout the Milky Way and possibly throughout the entire universe. For example, have you heard about the SETI project? Are they looking for intelligent life?
Yes. [Actually, I haven't.]
- As a rule, these are mathematicians, and they expect that the smart ones in some other galaxy will send them the number Pi or, you know, some other mathematical signal. In fact, they will only send DNA sequences.
That is, you say that life got here as it spread everywhere. Thus, if we send a DNA sequencer into space and find out that, based on the data it collected, all this spread, and then flew to Earth, and we are not at all the progenitors of everything …
- Exactly.
So, other people, those who have a different opinion on this matter, believe: "No, our form of life originated here, and other forms of life can be on other planets, and we can understand this thanks to methane" or something in this spirit? Therefore, we need to look for something like methane, because that way we can find completely different forms of life
- Exactly. This area of astrobiology is the area of people thinking about life on other planets. And there are probably, I don’t know, between a thousand and five thousand people calling themselves astrobiologists, and NASA has put a lot of effort into developing this area. And if you asked a thousand astrobiologists if they believe that life has spread or evolved independently, I would say that 1% would be ready to accept the idea of spreading life in the form in which I can say, promote it.
So, then, if 99% of scientists believe in global warming, and an insignificant minority says that it is not related to human activities or that it simply does not exist, be that as it may, we roll our eyes and say: “Well, this is not very something scientific. " These people are cogs in the fossil fuel industry and related areas. You are a highly respected scientist who is not considered an eccentric eccentric. Do you have any inner doubts?
“If I were a rational person, you would probably be right. [Laughs.] But I don't know why. It just makes sense. In fact, every textbook says that life happened on Earth, and this is a little improvisation - to say: you know, and we flew here. Do you understand? This, in a way, does not give any satisfaction, because it transfers the problem somewhere else to another sphere. Do you understand? But all the same, it had to start somewhere else.
I guess I got the idea that it’s so easy to go from a bag of chemicals to a full-fledged bacterium, and that this could happen in a couple of hundred million years on Earth. It's also important to understand that given the plate tectonics on Earth, our planet is very, very quickly erasing its history as continents shift and Earth's surface is rebuilding. It is very difficult to find samples that are more than three billion years old. There are not many of them on Earth. Therefore, it is rather difficult to search for the most ancient fossils here. And here we come to one of the advantages of Mars - there is no plate tectonics. Therefore, if you want to search for some ancient fossils on Mars, then there was no permanent burial of the past, unlike Earth.
What discovery on Mars can indicate the correctness or erroneousness of your theory?
- Well, I mean, again, if DNA sequencing was carried out there, which is a very sensitive process, right? Therefore, one could find extremely rare organisms on Mars. And if you found them, discovering at the same time that it is not easy, you know, some kind of dandruff or acne from someone from the assembly department of the spacecraft, that this is something with deep roots - that is, it is associated with life on Earth, but about the same as a kangaroo is an animal, but at the same time it is quite clearly different from anything that you saw in the Old World, then you would establish that you have discovered something new, right? And the same can be said for bacteria.
Or if the people from the SETI project one day received a four-character signal, like a DNA sequence, and you picked up a decryption code and said, "Oh my God, this looks like one of the genes we recognize," there would be proof that in genomics somewhere out there on another planet there is an exchange.
What discovery could convince you that you are mistaken, or that it was no coincidence that you found yourself in the minority?
- Well, if someone discovered a completely new form of life that was not built on DNA, I think it would be a good refutation of this idea of Panspermia.
I will let you go very soon, but what if life nevertheless originated here, and then spread further? And thus, we found some DNA on Mars, but it ended up there because it spread from Earth. Is it possible?
“Yes, but it puts us in the center of the universe, and the whole power of history lies in the appeal:“We must not assume that we are the center of everything. We are insignificant."
What are the religious reasons here? Do you see any kind of religious aspect in this discussion?
- Did I send you a link or ask you to search for a video? [Ravkan recommended that I watch a video on YouTube where he expresses his position on “life outside of Earth”.]
Yes, I watched this video
- In this video, I did something about which I was a little afraid: I referred to the wonderful motor of ATP synthase. It is one of the most amazing little mechanisms bacteria have for generating energy by pumping protons across membranes. And, essentially, they have a molecular motor that turns it on, I don't know, at a thousand revolutions per minute or so.
Therefore, the adherents of the intelligent theory - I am almost afraid to say this, because the last thing I would like to have my public statements interpreted by the supporters of the intelligent theory - they use the synthesis of ATP as a basis for their theory.
What is ATP synthesis?
“This is a small rotary hydraulic motor that generates ATP through proton pumps. This is a perfect miracle of evolution. And I want to emphasize that I think this is evolution, but religious fanatics use it to prove that evolution could not do it because it is so beautifully thought out.
And how does this relate to these two theories …
“Well, there are religious fanatics who follow the same example as me. I use this example to say, "This is the pinnacle of evolution." You see, three or four billion years ago, this is no longer a primitive form of life. This is a highly evolved life. She has already reached a high level of evolution.
Clear. And they claim that this proves the uniqueness of humans because God created them?
- Yes. And I say, "No, because much more time has passed than four billion years."
I thought you would say the opposite about the religious dimension, that your theory does not regard the Earth as the center of everything, therefore religious people do not believe in it. But the position of other scientists is at least closer to some religious beliefs, because they regard the Earth as the beginning
- Yes. I don't think - well, perhaps the orthodox view of the origin of life on Earth is rooted in Adam and Eve. I do not know. Perhaps I haven't had a single religious thought in my entire life.
It's a shock. How difficult is it to send such a sequencer to Mars? And can this happen in the near future?
- NASA is supporting us. Maria Zuber, a passionate planetary scientist, and I have worked together on this for nearly 20 years, and NASA has been supporting our work. This is a high-risk enterprise that they are ready to throw some money into, but they have not yet approved the flight. They haven't gotten to that yet. On the other hand, looking at how NASA organizes itself is pretty interesting. Every ten years, they conduct what is called the Decade Survey, when they walk and talk with planetary scientists in the US, Europe and the world, and ask them: "What project do you think is the most important?" Then it all spills out into a 200 page document, and if you look at their priorities, what is important to them as a space organization,then the search for life on other planets is priority number one.
Does the high concentration of methane play any role in this discussion?
"Most astrobiologists would say," Well, maybe there are methane-producing bacteria in there. " These bacteria, which absorb carbon dioxide, use hydrogen from the soil and generate methane. It's metabolism. And most astrobiologists would say, "By the way, methane can be associated with microbes." And so, yes, I think most people will like the idea of methane-producing bacteria on Mars.
And, probably, many of them will say, "Yes, the idea of having a connection with the methane-producing bacteria on Earth may not be that crazy."
So, let's summarize for clarity. From this conversation, I made the following conclusions: you believe in the theory of the intelligent beginning, you do not believe in global warming and adhere to insane theories about life on other planets
- Wait, wait. [Laughs.] Oh no, don't. It will be possible to give up my career.
Isaac Chotiner
