Tag Archives: aliens

Mathematical Proof that Aliens Do Not Exist (Sorry to Burst your Bubble)

Every now and then random people in the world go bat-guana crazy about something, whether it’s about a Big Foot sighting, or believing that a trust-fund billionaire troll-bot will govern for anyone other than other billionaires, or evidence of extraterrestrials. This latter went big in 2016, moving from cow-probing theory-spinning abductees to legitimate astronomers and physicists who tried really, really hard not to sound like they were talking about E.T.

However they tried to dress it up, it was ridiculous. A star, KIC 8462852 (now known as Tabby’s Star), was showing behaviour they didn’t recognise, and the cry of “ALIENS” reverberated around the internet. Sound like a familiar argument?

In fact, the probability of contact with extraterrestrial intelligence is so tiny that there is literally no evidence compelling enough to refute the maths. I explain this here.

The Multicellularity of Alien Life Forms

The latest news out of biology (well, it’s been building for quite a long time) is that the tree of life is very different from how we thought it was. The bit that got me excited?

In the new vision — based on increasingly sophisticated genetic analyses — people and other animals are closer cousins to single-celled choanoflagellates than to other multi­cellular organisms. Giant kelp that grow as wavering undersea forests off the California coast are closer relatives to single­-celled plankton called diatoms than to multicelled red seaweeds or plants.

This is because it obliterates the notion that multicelluarity evolved only once. In fact, Wikipedia claims “complex multicellular organisms evolved only in six eukaryotic groups: animals, fungi, brown algae, red algae, green algae, and land plants. It evolved repeatedly for Chloroplastida (green algae and land plants), once or twice for animals, once for brown algae, three times in the fungi (chytrids, ascomycetes and basidiomycetes) and perhaps several times for slime molds, and red algae.” This is cool because it removes one of the bottlenecks for intelligent life: The chances of life spontaneously evolving are vanishingly small (once that we know of), and the chance of eukaryotic life developing is also vanishingly small (once that we know of). However, where in the past it was thought* that multicellularity evolved only once, now it seems a common, and therefore inevitable, occurrence.

Which means, if we do find extraterrestrial life, it will almost certainly be multicellular in some way.

*At least by me, and it seemed to be the general thought when I went through uni 20 years ago. I don’t know how long scientists dedicated to the field have been aware of this.

For more alien life science, see Life In Cryogenic Conditions.

Non-Polar Membranes

Life In Cryogenic Conditions

A pretty interesting resource for science fiction writers just popped up. It considers the evolution of life in extremely cold places, such as Saturn’s moon Titan where the surface temperature is about –179 Celsius, specifically what sort of membranes might be available for life to use. In addition to the extremely low temperature which would insta-freeze most molecules into solids, at that temperature the liquid oceans are composed of methane, which is non-polar… so that has to be taken into account.

The researchers at Cornell University ran a computer model with the compounds that we’ve detected in Titan’s atmosphere, and come up with acrylonitrile as the best candidate to form membranes in those conditions. They’ve termed these membranes azotosomes (as opposed to the liposomes that make up our cells) and have calculated they have pretty much the same characteristics as liposomes. Acrylonitrile has three carbons, three hydrogens and a nitrogen, which makes the membrane a lot thinner than liposomes, but that’s pretty much a requirement for working at such a low temperature. The other main difference between azotosomes and liposomes is that in terrestrial liposomes the oxygen-powered polar head is on the outside, interacting with water molecules, while the non-polar tails create the inner barrier, while azotosomes have the nitrogen-powered polar head on the inside of the membrane, and the short non-polar carbon tails interacting with the liquid methane. This can be seen in the image above, where A is a lipid membrane and B the hypothesised acrylonitrile one.

This is not proof of life on Titan, of course, but it’s evidence that at least one of the necessary components for life – compartmentalisation – is possible on that moon. The other components of metabolism are still necessary, and I wonder how they’d run at that temperature; would reactions necessarily be far slower than those of life on Earth, and if so how would that affect the organisms? How would that affect a sentient organism?

Scientific American Article
James Stevenson, Jonathan Lunine, Paulette Clancy: Membrane alternatives in worlds without oxygen: Creation of an azotosome, Science Advances Vol 1, No 1.