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The Origins of Directed Panspermia

The views expressed are those of the author and are not necessarily those of Scientific American.


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The Earth is beaming with life and yet there is no consensus on how life arose or what life is. The origin of life is “one of the great unsolved mysteries of science” (Crick, F. Life Itself).  While there is no accepted definition of life, most of us [humans] can easily discriminate the living from the non-living (IrisFry’s Book is a good primer on ideas regarding the origins of life). Questions about the origin of life became more prevalent after Pasteur and others showed that life did not arise spontaneously.

The discovery that the raw components of life are present throughout the universe suggests that life could exist elsewhere, and that the origin of life as we know it may have depended on materials that arrived on Earth via inter-stellar travel. Some scientists have speculated that life itself originated elsewhere and made its way to earth.

In 2012 a movie called Prometheus was released. In this stunning movie human scholars find similarities between archeological sites from ancient civilizations separated by centuries have drawn the same pictogram.  The archeologists conclude that the pictogram must be a map, an invitation, from the “engineers” who not only designed us but have intervened in our affairs. The movie is set in 2093 and researchers decide to go and find them in a quest to further understand the origins of mankind. Despite its several and severe scientific flaws, Prometheus is an interesting film because it addresses that ever mysterious quest to unveil not only how we came to be but how life began.

Mars Curiosity

Life in space has been making the news, and on November 20th 2012, NPR reported that NASA’s Mars Curiosity rover had gathered important data. Mars holds a special place in our world. The principal Mars’ rover investigator, John Grotzinger claimed “This data is gonna be one for the history books. It’s looking really good,”. He refused to give any more details because his team had to confirm their findings. In general, this is good practice because scientists want to avoid finding superfluous results and correlations; however, in this case, it heightened suspicion.

Shortly thereafter NASA tried to downplay Grotzinger’s statements, pointing out that it was the mission which was historic rather than a specific finding.  Despite this backtracking some speculated that organic compounds had been found, some claimed that it was life that had been discovered. On December 3rd NASA confirmed, Curiosity had found Organic compounds but it was uncertain whether they were indigenous to Mars (or had been brought by Curiosity).

Most of the speculation had suggested that organic compounds were the “historical finding”. These are also important because they confirm that the stuff of life, the raw materials, are far more common than originally thought (as corroborated by the discovery of signs of water and organic molecules in mercury), or the finding of organic molecules in meteorites.  Like the discovery of extremophiles which showed that once life got started it could be found in unexpected places; the advances in the search for extraterrestrial life suggest that the stuff of life, and hence life, could be commonly found throughout the universe.

Molybdenum

Molybdenum

Francis Crick (who co-discovered the structure of DNA with James Watson) and Leslie Orgel once proposed that life on Earth was the result of a deliberate infection, designed by aliens who had purposely fled mother nature’s seed to a new home in the sun.  Crick repeatedly addressed the question of the origin of life between 1971 and 1988 (I am currently working on a historical study of Crick and Orgel’s theory of Directed Panspermia and its reception).

Crick and Orgel proposed their Directed Panspermia theory at a conference on Communication with Extraterrestrial Intelligence, organized by Carl Sagan and held at the Byuraka Observatory in Soviet Armenia in 1971. This theory which they described as an “highly unorthodox proposal” and “bold speculation” was presented as a plausible scientific hypothesis. Two years after the conference they published an article in Icarus on 1973.

Crick and Orgel were careful to point out that Directed Panspermia was not a certainty; but rather a plausible alternative that ought to be taken seriously. In the paper Crick and Orgel recognised that they “do not have any strong arguments of this kind, but there are two weak facts that could be relevant”. The 1973 paper focuses on the universality of the genetic code and the role that molybdenum plays in living organisms (I am likewise working on a history of molybdenum and the origins of life) which is more than one would expected given the abundance of molybdenum on the earth’s crust.

Francis Crick and Leslie Orgel. (Circa 1993)

Crick and Orgel used the universality of the genetic code to support the theory of directed panspermia because if life had originated multiple times or evolved from a simpler genetic code one could expect living things to use a slew of genetic codes. Further, if there was only one code, Crick and Orgel reasoned that as organisms evolved they should evolve to use the same codons to code for different amino acids.

We can draw a parallel to language: while many human populations use the same symbols (letters), they combine them in different ways. These different languages use the same alphabets but different combinations of the same symbols to denote different objects (French, Italian, Spanish, Portuguese, Catalan) as opposed to different codes (languages which uses different alphabets like Spanish and Mandarin); however, what we find is analog to a single universal language.

Their most convincing argument was the importance of molybdenum in organic processes and its relative scarcity on Earth. They had argued that living organisms should bear the stamp of the environment in which they originated. Organisms, Crick and Orgel held, would be unlikely to develop a dependency on elements that were extremely rare as organisms that relied on elements which were more abundant would be favored by selection.  An organisms that was able to substitute the rare element for one which has similar biochemical properties but is more frequent would have a clear advantage.

Crick and Orgel pointed out the “anomalous abundance of molybdenum” in organisms made it possible that life arose in an environment rich in molybdenum. The abundance of molybdenum in living organisms suggested that life started in a molybdenum rich environment and they found that the Earth is not sufficiently rich in molybdenum (this was later challenged as the amount of molybdenum found in the ocean is higher than in the Earth’s crust). Thus, they suggest that this difficulty could be resolved if life began in a molybdenum rich environment. Likewise, the fact that all organisms use the same codons for the same amino acids could be explained if life had arisen elsewhere and the organisms which were used to infect lifeless planets shared a language.

Crick and Orgel also suggest that the universe is sufficiently old that other intelligent civilizations could had arisen elsewhere. One of these other intelligent civilizations could have built a spaceship and seeded the universe with life. One can easily imagine a not too distant future where humans accept that our planet and all that lives within it will perish. In the unlikelihood that this is the only planet that harbors life in the universe its demise would leave a lifeless universe.

The demise of our kind is hard enough to accept but the prospect of a lifeless universe, a universe that could never come to know itself, a universe so grand and yet with no one to admire it or even dwell in it could be too much to bear. In order to save our kind we can envision our zealous and hard working descendants endeavoring to colonize other worlds (by sending microbes through interstellar journeys). Microorganisms are easier to transport and could more readily adapt to new conditions; sending larger organisms would be too difficult (Crick and Orgel pointed out).

The origins of life remains an unresolved mystery. I argue that Crick and Orgel’s paper was meant both as a serious and plausible scientific alternative and as a means to criticize concurrent origins of life. Considering the life arose elsewhere could also free scientists studying the origin of life from trying to imitate the alleged conditions of a pre-biotic Earth. My ongoing research suggests that while Orgel abandoned Directed Panspermia, Crick continued to advocate for its viability and to argue in its favor. Our continued exploration of space will, presumably, continue to reveal the existence of organic compounds in space (and quite possibly life) and hence suggest that the universe may be beaming with life.

Images: Mars Curiousity by NASA; Molybdenum by Alchemist-hp at Wikimedia Commons; Francis Crick and Leslie E Orgel from FASEB journal.

Christian Orlic About the Author: Christian Orlic is currently a graduate student in Zoology and he is study experimental evolution at Michigan State. Christian has a BSc in Zoology and one in the History of Science. Christian is currently working on an extended history of Crick and Orgel's theory of Directed Panspermia and its reception by the scientific community. (I do not quite know what to do for an author bio). Follow on Twitter @christian_orlic.

The views expressed are those of the author and are not necessarily those of Scientific American.






Comments 16 Comments

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  1. 1. RSchmidt 2:29 pm 01/9/2013

    The Panspermia hypothesis is an interesting one and should be taken seriously but it suffers from Occam’s Razor. If life on Earth is consistent with an Earth origin then Panspermia becomes the more complicated hypothesis. It then requires evidence that is inconsistent with an Earth origin of life to be worth consideration. Still, it is an option that should be left open.

    Also, if life was possible on Earth without the need for Panspermia I would think that native life forms would be able to out-compete lifeforms that had evolved in a different environment. So even if earth was seeded with life from mars or Thea or wherever there may be no trace of it, it may not have survived first contact.

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  2. 2. Bora Zivkovic 2:46 pm 01/9/2013

    I am glad to see this studied from a historical and sociological perspective. I’d also like to see a psychological persepctive, i.e., why are some people attracted to hypotheses like Directed Panspermia?

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  3. 3. Andrew Planet 3:15 pm 01/9/2013

    Empirically, life is the chemical evolution of the universe to a point where it can ultimately be aware of itself, in varying degrees of perception, otherwise this explicative text on this webpage would not exist.

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  4. 4. eogord 4:52 pm 01/9/2013

    These theories skirt the issue ‘how and with what did life begin’ It’s kicking the can, from one place to another, but doesn’t answer-how, and with what and what made it self replicating. I don’t see the requirement to engage in constructing extraterrestrial sources. Earth was probably a good nursery. The mystery remains, no matter where.

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  5. 5. Acoyauh2 7:27 pm 01/9/2013

    @ 4. eogord: Sure, ‘sending’ the origin elsewhere does not solve the question of the origin of life. However, clarifying whether or not it actually originated here is a valid question, additional to the how. How and where should be the question.

    Personally, I find the concept of panspermia quite compelling, though *Directed* panspermia does seem a bit far-fetched.

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  6. 6. dwbd 8:54 pm 01/9/2013

    The possibility of directed panspermia & also random panspermia just enforce the seriousness of Fermi’s Paradox. Not only can any alien civilization that arose anytime in the past 13 billion years in our local Galactic Cluster, on any of 100 billion perhaps a trillion suitable planets, would easily spread throughout our Galaxy in a matter of a Billion years or so, simply through geometric expansion, but any one of millions of their settled Worlds could send out Life Bombs to other Worlds throughout our Galaxy and other nearby Galaxies.

    And why send just bacteria? Why not small colonies of multi-cellular life, that even survive on deep-sea geothermal vents? Save 4 billion years of evolution. Why not self replicating robotic organisms? And keep in mind the Galaxy is not static. Stars migrate close to other stars. Galaxies collide and pass close by each other.

    The reality is there are only two scenarios for life in a galactic cluster, that are anything more than remotely probable:

    1) intelligent life everywhere
    2) no life anywhere

    And since intelligent life has arisen here easily enough and with plenty sufficient speed, option 2) is extremely unlikely.

    So we are left to conclude:

    1) We live within some sort of simulation that specifically restricts the development of life to a few or only one world.

    2) Just add another instance of the Anthropic Principle, that states if things had occurred anywhere near remotely probable, we wouldn’t exist, aliens would long ago have populated our entire galaxy, barren worlds, remotely habitable, would be as rare as a cheap beachfront property in Hawaii, and we wouldn’t be discussing this issue. This seems to imply that there are perhaps infinite universes and even incredibly bizarre and unlikely cases like our Galaxy, almost but not quite, barren of life, do occasionally happen.

    On the bright side, if we are in a simulated universe, as seems most likely, the simulation may include another partner civilization to ours, similarly developing in a nearby solar system, that we might hope to interact with in the near future. Add a little spice to the simulation.

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  7. 7. vinodkumarsehgal 5:47 am 01/10/2013

    Most of the studies on origin of life and panspermia are based upon one core assumption namely synonymous character of organic compounds and life. It is not understood as to how chemistry of organic compound can lead to creation of life. Organic compounds and water may be found at many places in universe but this should not lead to inference that life shall also be present there. Lakes of methane have been found at Titan, a moon of Saturn but this should not lead to inference that Titan shall have life also

    Had only organic compound been the life , by this time life could have been synthesized artificially in lab without biological intervention.

    Though presence of organic chemistry of some compounds may be the prerequisite for the emergence of life but to brand organic chemistry, however evolved it may be, per se as life appears to be highly naive. It is suggested that life emerges out when organic chemistry of certain compounds are interfaced with some external agent which Science has yet to know. In fact, though organic chemistry can be easily defined and studied but there is no consensual understanding as to “What is life?”

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  8. 8. vinodkumarsehgal 6:21 am 01/10/2013

    With or without panspermia, whether directed or random one, odds appears fairly high of existence of life at other place(s) also in universe apart from earth. This notion emerges out basically from two observations.

    Firstly spatial vastness of universe. Astronomers have estimated minimum 100 billion galaxies in observable universe only with each galaxies containing billion and trillion of stars and planets. If life came as part of some accident, as materialists assert, there is no reason that this accident should occur at earth only and trillions of location elsewhere in universe should remain devoid of this accident i.e emergence of life particularly when organic matter and water for emergence of life can be present elsewhere also. If life appeared on earth as a part of some grand intelligence design, there appears no reason that such a design may be so imperfect that it may create life at one place only, out of trillion of locations, and keep almost entire universe barren of life.

    Secondly, vastness of time scale of universe. Cosmologists estimate age of universe at about 13.7 billion years while earth age is estimated at about 4.5 billion years. It is estimated that life appeared at earth about 3 billion years ago. If life was/is present at earth only, does it appears logical and rational that during the first about 10.7 billion years, there was no life in universe and then it suddenly appeared on a small planet in a desolate corner on earth? There is high unlikelihood of this scenario.

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  9. 9. sandymx4847 4:31 pm 01/10/2013

    Twice in this article, in the paragraphs beginning “Their most convincing argument…” and “The demise of our kind…”, the verb “bare” is used when context seems to indicate that the verb “bear” was intended. This type of error seems much more common in this online medium versus the corresponding print version of Scientific American.

    Is reasonable proofreading too much to expect of this state-of-the-art scientific publication?

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  10. 10. tflahive 5:24 pm 01/10/2013

    How did any organism survive in space? There are three major problems of survival in space: 1) Vacuum, 2) Radiation, and 3) Cold. If an organism survived all these problems, we need that technology to advance human space travel.

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  11. 11. Postman1 10:05 pm 01/10/2013

    Interesting article.
    You stated: “as opposed to different codes (languages which uses different alphabets like Spanish and Mandarin)”
    The Spanish I learned used the same alphabet as English. Perhaps you meant Arabic, or Hindi, or ?

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  12. 12. jgrosay 10:29 am 01/11/2013

    I’d say that the presence of enzyme systems in the living organisms that use Molybdenum is not a reflect of the origin of life in an environment with a high Molybdenum content, but just a consequence that the functions Molybdenum performs in these enzymes can be done by Molybdenum, and only by Molybdenum, or that Molybdenum is the element most suitable for the function it makes. The subject may be not a Biology problem, but a problem of Quantum chemistry or something related to this. That an imaginative proposal has been done by somedy with a highly successful career or achievements in other fields of science doesn’t add nothig to the reliability of his/her proposals, it just means that more people would trust these postulates. Salut +

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  13. 13. bucketofsquid 2:41 pm 01/11/2013

    @sandymx4847 – Blog post! Blog past! This is not an edited article. Get with the current millennium and stop being a dork. It is OK and probably good to be a grammar Nazi but direct the corrections/complaints to the author and not the magazine.

    @tflahive – It isn’t technology. It is biological adaptation. If you want to become a single celled organism feel free to do so, just don’t expect it to be popular.

    In response to this blog post – I think that this might be the origin point of life because it had to start somewhere. Either way, origin point or not, we have a responsibility to spread life as far and wide as we can.

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  14. 14. GreenMind 7:04 pm 01/12/2013

    In my opinion, the uniformity of the genetic code is not evidence of seeding. Any slight improvement in growing or duplicating the genetic material will result in quickly outgrowing all competitors, just as a simple result of exponential growth. I don’t really think that all different forms of life converged on the same genetic code just because it was more efficient. Rather, of all the organisms that used all different genetic codes, the one that was incrementally the most efficient was the one that beat out all the rest. There was plenty of time for slight differences to result in an efficiency race between organism.

    On top of that, there were several enormous revolutions that had the potential for one or a few strains of bacteria to drive all the other ones to extinction, except maybe those buried in rocks.

    One was the ability to eat other organisms instead of just taking in chemicals from the primordial soup. That will thin out the competition in a hurry, and leave no traces of any of the competition.

    At some point an organism started using chemical energy to drive its activities, and started synthesizing what it needed instead of waiting for lightning or UV light to make it from the primordial soup.

    A big one was the evolution of photosynthesis, that filled the atmosphere with poison gas, oxygen. The photosynthesizing organism itself would have to be capable of living with oxygen, but anything not buried in rocks, that could not adapt, died. Huge bottleneck for living organisms.

    Then the presence of oxygen created the opportunity to get lots more energy from metabolism, so another efficiency race took off.

    All these factors would tend to let evolution home in on one genetic code.

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  15. 15. GreenMind 7:10 pm 01/12/2013

    tflahive, there are many archaeobacteria that live inside rocks. If a big enough asteroid hit a planet, it could blast a big chunk of rock into space, and that would protect it from vacuum and radiation. As for the cold, bacteria can be frozen and then thawed out.

    I’m not sure archaeobacteria could survive a slow trip between stars, but when stars come close to each other their systems might cause great havoc with each other, and maybe a lot of asteroid strikes would happen, letting them exchange bits of planet as they passed each other.

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  16. 16. GreenMind 7:15 pm 01/12/2013

    jgrosay, I like that idea. An organism has no idea whether a chemical is rare or not. If a chemical pathway is more efficient, it will evolve. It doesn’t matter why it is more efficient. It could be because there is more of an ingredient like molybdenum, or because the molybdenum is so much more efficient that it makes up for its rarity. It is the same as far as evolution is concerned.

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