Just how many forms of life are there? We often speculate here about life on other worlds, but Paul Davies (Arizona State) is currently exploring the question from a different perspective entirely. Davies would like to know whether a ‘second genesis’ might have occurred, producing a fundamentally different form of life that would have evolved right here on Earth and might still occupy our planet. Life may, in other words, have started many times, perhaps with significantly different results we just haven’t uncovered yet.
Call it a ‘shadow biosphere,’ a concept the physicist calls for exploring:
“…[It] is still just a theory. If someone discovers shadow life or weird life it will be the biggest sensation in biology since Darwin. We are simply saying, ‘Why not let’s take a look for it?’ It doesn’t cost much (compared to looking for weird life on Mars, say), and, it might be right under our noses.”
Finding these alternate life forms, if they exist, may be tricky, as they could be lurking in places where conditions are extreme, such as deep sea hydrothermal vents, salt lakes or areas high in ultraviolet radiation. And as Davies told a symposium at the AAAS annual meeting in Chicago, our assumptions about biochemistry may be getting in the way of our finding life in the shadow biosphere. “We don’t quite know how weird life would look. It’s as wide as the imagination and that’s why it’s really hard to look for.”
That last quote comes from a BBC story on the possibilities of alien life forms on Earth. The question Davies is asking is profound, for if life did get its start multiple times on our planet, we can assume it’s far more likely to have appeared elsewhere in the universe. The case for life on those trillions of habitable planets Alan Boss talks about in yesterday’s entry becomes more and more formidable. The BBC story cited above also discusses the work of Steven Benner (University of Florida), whose team has created what Benner calls “…an artificial synthetic chemical system capable of Darwinian evolution.”
Benner says the molecule — a modified version of the DNA double helix but with a six-letter genetic alphabet instead of four — is not self-sustaining (“You have to have a graduate student stand there and feed it from time to time”), but it is evolving. He wants to apply natural selection to it to watch it evolve under selective pressure. So is Benner’s creation alive, or are we basing too much on our Earth-based assumptions? “Remember – just because you are a chemical system which is self-sustaining and capable of Darwinian evolution, that doesn’t mean that is the universal definition of life,” the scientist adds.
A useful caveat. The question that hovers over our first encounter with truly alien life, assuming it is out there, is not what we’ll say to it as much as whether or not we’ll even recognize it as life. Last April I quoted Jacob Bronowski on this in a statement from The Ascent of Man that bears repeating:
“Were the chemicals here on Earth at the time when life began unique to us? We used to think so. But the most recent evidence is different. Within the last few years there have been found in the interstellar spaces the spectral traces of molecules which we never thought could be formed out in those frigid regions: hydrogen cyanide, cyano acetylene, formaldehyde. These are molecules which we had not supposed to exist elsewhere than on Earth. It may turn out that life had more varied beginnings and has more varied forms. And it does not at all follow that the evolutionary path which life (if we discover it) took elsewhere must resemble ours. It does not even follow that we shall recognise it as life — or that it will recognise us.”
As to Davies, I’m looking forward to this prolific author’s next book. The Eerie Silence, scheduled for publication next year, is to be a new look at SETI and its dilemmas. Davies wrote up the ‘weird life’ concept in “Are Aliens Among Us?” Scientific American Vol. 297; No. 6, pp. 36-43 (available online). Thanks to Dave Moore for the tip on this story.
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A novel by Frank Schätzing picks up this issue in the form of a good thriller. The Swarm is a bestseller in Germany since 2004 and was translated into 18 languages. It assumes the existence of a collective intelligence living in deep sea called “Yrr”, which set up to destroy the human race, because humans devastate the oceans, Yrr’s habitat. You may get a bit more feeling on the story in the Wikipedia here.
Read it, it is enthralling.
The possibilities are endless since we can’t monitor large volumes of molecular activity to see what springs up. It’s possible we’re missing the wood for all the trees and the very air around us is full of life-as-we-don’t-yet-know-it. All the fuss over nanobes a few years ago – and the back-down on their “life” status – illustrates the puzzle well. The idea of “life” without ribosomes didn’t sail with other biologists. Yet do we have any option? Life is too complex, as it is, to be produced directly from random amino acids and nucleosides. We’re not going to get self-propelled homeostatic molecular systems straight from raw materials. Systems of interacting small molecules – call it “simple life” – must’ve preceded life as we know it, and probably still exists as the underlying systems of chemical interactions embedded in present metabolic cycles, and may yet persist where conditions are right. I think something like that is what Davies is arguing and what other origin of life researchers have concluded. Life ISN’T a fluke. It’s implicit in the laws of physics and their outworkings in chemistry.
Second Genesis: Life, but not as we know it
11 March 2009 by Bob Holmes
Magazine issue 2699
Part 1: Making new life
Part 2: The search for shadow life
Gallery: What might shadow life be like?
WHEN the Nobel prizewinning physicist Richard Feynman died in 1988, his blackboard carried the inscription, “What I cannot create, I do not understand.”
By that measure, biologists still have a lot to learn, because no one has yet succeeded in turning a chemical soup into a living, reproducing, evolving life form. We’re still stuck with Life 1.0, the stuff that first quickened at least 3.5 billion years ago. There’s been nothing new under the sun since then, as far as we know.
That looks likely to change. Around the world, several labs are drawing close to the threshold of a second genesis, an achievement that some would call one of the most profound scientific breakthroughs of all time.
David Deamer, a biochemist at the University of California, Santa Cruz, has been saying that scientists would create synthetic life in “five or 10 years” for three decades, but finally he might actually be right. “The momentum is building,” he says. “We’re knocking at the door.”
Meanwhile, a no-less profound search is on for a “shadow biosphere” – life forms that are unrelated to the life we know because they are descendants of an independent origin of life.
We know for sure that life got going on Earth once, so why couldn’t it have happened twice? Many scientists argue that there is no reason why a second genesis might not have taken place, and no reason why its descendants should not still be living among us.
Full article here:
Regarding Paul Davies, I have become more wary of his views on
SETI as of late. Recently he had an op-ed piece in the New York
Times saying that since scientists did not know exactly how the
Universe was created, their views are no more or less valid than
religious takes on the subject. That shows a rather profound lack
of understanding of science and from a scientist no less to me.
Thursday, September 10, 2009
How to Create Quantum Superpositions of Living Things
First photons, atoms and molecules. Now physicists want to create a quantum superposition of a virus, which will allow them to perform Schrodinger’s Cat experiment for real.
One of the great challenges for quantum physicists is to find quantum behaviour in macroscopic objects. There are obvious examples of quantum behaviour on a large scale, such as superconductivity and superfluidity, but physicists want more.
Having created quantum superpositions of photons, electrons, atoms and even molecules, one of the current obsessions is to create a quantum superposition of a living thing, such as a virus. The question is how to do this and whether it makes any sense to say these things are living at all.
This is an experiment that will be hard. But today Oriol Romero-Isart from the Max-Planck-Institut fur Quantenoptik in Germany and a few buddies suggest that it is achievable with current technology and outline the challenges that will have to be tackled to pull it off.
The experiment will first involve storing a virus in a vacuum and then cooling it to its quantum mechanical ground state in a microcavity. Zapping the virus with a laser then leaves it in a superposition of the ground state and an excited one.
This works only if the virus behaves like a dielectric, can survive the vacuum and appears transparent to laser light, which would otherwise rip it apart.
As luck would have it, Romero-Isart and co say that several viruses fit the bill. The common flu virus is known to be able to survive in a vacuum, seems to have the required dielectric properties and may well be transparent to a careful choice of laser light. The tobacco mosaic virus, to all intents and purposes a dielectric rod, looks like another good candidate.
But does it make any sense to say that a large molecule in its ground state is somehow alive? It’s difficult enough now to define what life means. Throw a quantum superposition into the mix and the biologists who ponder these problems are likely to implode.
Nevertheless, many groups are currently looking to create superpositions of things like tiny cantilevers and micromirrors, so viruses certainly look achievable in the near future. And beyond that, why not bigger organism such as the tardigrade (or water bear) which can grow to 1.5 mm in length.
But why bother? Performing a Schrodinger’s cat experiment would be fun (although not for the virus). Romero-Isart and pals go further and say the work will “experimentally address fundamental questions, such as the role of life in quantum mechanics,and differences between many-world and Copenhagen interpretations”. Perhaps.
But their contention that it will also address “the role of consciousness in quantum mechanics” seems a step too far (although a flu virus may beg to differ).
Ref: http://arxiv.org/abs/0909.1469: Towards Quantum Superposition of Living Organisms
September 17, 2009
Searching for Life As We Don’t Know It
Written by Nancy Atkinson
When discussing the possibility of finding life on other worlds, we usually add the phrase “life – as we know it.” But we’ve been surprised at exotic forms of life even on our own world and we need figure out how life might evolve elsewhere with foreign biochemistry in alien environments.
Scientists at a new interdisciplinary research institute in Austria are working to understand exotic life and how we might find it.
Traditionally, planets that might sustain life are looked for in the ‘habitable zone’, the region around a star in which Earth-like planets with carbon dioxide, water vapor and nitrogen atmospheres could maintain liquid water on their surfaces. Consequently, scientists have been looking for biomarkers produced by extraterrestrial life with metabolisms resembling the terrestrial ones, where water is used as a solvent and the building blocks of life, amino acids, are based on carbon and oxygen. However, these may not be the only conditions under which life could evolve.
The University of Vienna established a research group for Alternative Solvents as a Basis for Life Supporting Zones in (Exo-)Planetary Systems in May 2009, under the leadership of Maria Firneis.
“It is time to make a radical change in our present geocentric mindset for life as we know it on Earth,” said Dr. Johannes Leitner, from the research group.
“Even though this is the only kind of life we know, it cannot be ruled out that life forms have evolved somewhere that neither rely on water nor on a carbon and oxygen based metabolism
Full article here:
Horizontal and vertical: The evolution of evolution
New Scientist Life Jan. 26, 2010
The most ancient and prevalent form
of evolution — and the genetic code
itself — probably wasn’t Darwinian
at all, but “horizontal gene
transfer,” say University of
Illinois at Urbana-Champaign
scientists Carl Woese and Nigel
Goldenfeld. In horizontal gene
transfer, change is not a function
of the individual or of changes from
Deep-sea Vents Yield New Species
Scientists explore the Mid-Cayman Rise in the Caribbean
Call it “midnight at the OASES.” Neither permanent darkness nor extreme pressure and heat cause problems for a host of new deep-sea species found in January by an international research expedition called “OASES 2012.”
The expedition, led by Woods Hole Oceanographic Institution geochemist Chris German, explored hydrothermal vents on the seafloor in the Caribbean, which spew out super-heated chemical-rich fluids that provide oases for life forms in the dark, cold depths. The researchers returned with specimens and a new appreciation for the ability of life forms to adapt to some of the harshest conditions on Earth.
The researchers first found evidence of the vents on a cruise in 2009. They returned to the area this year aboard the research vessel Atlantis with the remotely operated vehicle Jason and specialized sampling equipment to study the chemistry, geology, and biology of the vents at the Mid-Cayman Rise. The cruise, funded by the National Science Foundation, also hosted a blog featured on the WHOI website.
Full article here: