The RNA world hypothesis has been around for quite a long time as an origin of life theory (alongside others such as the iron-sulfur world and the newer aromatic world theories). Actually, the concept dates back as far as 1963. The idea is, essentially, that RNA can act as an enzyme, store information, and self-replicate. As such, many have favoured the idea that strands of RNA might have been evolving chemically long before cellular life developed.

Well, a research group at the Scripps Research Institute have hacked some RNA, creating a kind of molecular 'ecosystem'. It's not actually a living system, but a collection of molecules which evolve and compete the way living organisms do.

The team have been tinkering with these molecules for the past 8 years, creating pairs which require each others' help to reproduce. Effectively, sexual reproduction in molecular form. As a result, once these molecules were in solution, some of them gave rise to random mutations. Just as in living ecosystems, most mutations rapidly died out, but a select few proved to be beneficial. So beneficial, in fact, that after a mere 77 replications all the original molecules were extinct. A variety of forms came into existence with 3 highly successful molecules dominating the population.

Chemistry acting like biology. Fascinating. Simply fascinating.

The big question though is, could any other molecules could act this way? RNA is, after all, fairly advanced as molecules go. At what stage in a prebiotic system does chemistry start to act in a lifelike way?

The journal paper was published recently in Science, if you happen to have a subscription (or a nearby library).
Tip of the hat to ranka for posting that link!

I found this, courtesy of Mike the Mad Biologist.

It's around three centimetres (or one attoparsec) in diameter, perfectly spherical, leaves trails in the mud and was discovered off the coast of the Bahamas.
Believe it or not, this is a single celled organism.



Gromia sphaerica is a gigantic relative of the amoeba. It's been discovered before, but this is the first time it's been seen actually moving -- rolling along and leaving trails behind it in the mud. Trails which apparently are making some palaeontologists question conclusions they came to over similar trails seen in precambrian fossils.

One could speculate that perhaps life experimented with how large single cells could grow before 'going multicellular'. Perhaps we might eventually find similar things rolling around on the surface of Mars. They're certainly decidedly alien compared to the more familiar forms of life we know about. You have to wonder if perhaps life elsewhere might find some kind of optimum cell size. Perhaps life on giant planets (as Sagan envisaged in Jupiter's clouds) might evolve to encompass cells even larger. Imagine a multicellular life form composed of cells this size!


EDIT-- I found a little slideshow about these things, courtesy of Crowlspace.

So a big puzzle in astrobiology is where exactly we might find life and what form it may take. Most scientists regard life as having a few prerequisites to exist in the first place; notably water, oxygen, carbon, a temperature between 0-50°C... It's a fair assumption to make, given that we only really have the Earth as an example.

But with a sample size of one, we're really in no place to be drawing up hard and fast rules. We really don't know what conditions life could thrive in. We don't even know for certain what life might be made of.

So here are my top 10 most unusual life forms. Extremophiles, or living things that are just plain unusual. Obviously, all of these things exist on Earth. If life like this can exist on Earth, it can exist elsewhere. If similar things can exist, then by probability alone, it's no leap of faith to say that they probably will exist somewhere. The only question we need to ask is where.



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Now I don't go all biological that often, but sometimes you hear about something that just makes you stop and think... "Wow."

A team based in Basel, Switzerland has come up with a nanotechnology that could turn out to be wonderful. Basically, they've figured out a way to make artificial organelles which can be inserted into cells. An organelle is a membrane-bound substructure within a cell that performs functions for that cell. Chloroplasts, for example, are the cell structures that perform photosynthesis in plants. All manner of other organelles exist, from mitochondria to golgi bodies, and these collectively make up the machinery of the cell, producing energy, sorting proteins or simply storing nutrients.

Dubbed 'nanoreactors' these artificial organelles work similarly (albeit more simplistically) to their natural counterparts. Essentially, a nanoreactor is a polymer capsule containing certain enzymes. The polymer membrane regulates what chemicals can enter and leave the nanoreactor, and the enzymes inside do their thing. This has all manner of potential uses, from increasing the efficiency of a cell's natural functions to delivering targeted anti-caner agents. An anti-caner drug could be introduced directly inside the malignant cells, leaving any normal ones untouched.

Oh, but it gets better. Team member Wolfgang Meier points out the interesting fact that these things don't have to stop at increasing cell efficiency. Potentially, they could get human cells to perform non-human functions. There are all sorts of tricks in nature that humans could find useful. Crocodile haemoglobin, for instance, could allow people to hold their breath for an hour at a time. Artificial chloroplasts could even allow human cells to photosynthesise. Just imagine that... Save money on food by sunbathing!