Intriguing 'autocatalytic' reactions appear to be far more common than scientists had thought.
Alien life may not be carbon-based, new study suggests::Self-sustaining chemical reactions that could support biology radically different from life as we know it might exist on many different planets, a new study finds.
You can eat them if they have the nutrients you need. Non-carbon-based just means it won't use carbon as the foundation of its molecular and cellular workings. By mass, there's relatively little carbon in living organisms and on earth, so whatever's out there could still use carbon and other elements enough that it has something we could eat. There's barely any telling what kinds of chemicals will be found in an organism like that, but it could easily be a mix of things we can digest and things we can't. Even carbon-based life is like that. Wood for example is biologically very similar to us, but is mainly made of cellulose, which we can't really digest at all.
By mass, there's relatively little carbon in living organisms and on earth
Some quick googling tells me about 60% of our body is water, and of what is left, almost half is carbon. This would include all of the fats, carbohydrates and sugars that we need for energy.
If you ate a non-carbon based lifeform, you might get some water or iron and other minerals you need a little of in your diet, but the reason we need to eat so much is to ingest different forms of carbon to digest.
An alien that died on earth would probably not even rot because our food chain is so dependent on our proteins.
Both of those questions will depend on what kind of environment they need to survive. They might need pressures higher than we can or a pH that would be corrosive to us, or exposure to an chemical that is toxic to us like oxygen was to most life that was around when photosynthesis started producing it.
If we can make physical contact with it, we'll be able to eat it. But if it is based on a different chemistry, I doubt there will be much nutritional value for us as our proteins and vitamins are all based on our chemistry. Hell, there's a good chance we won't get much nutrition from alien life based on the same chemistry because they might have evolved with a completely different set of proteins that might do things similarly but connect with each other a bit differently. There's a symmetrical set of proteins that look like mirror images of ours and would behave exactly the same, but aren't compatible with ours.
Opposite sugar would be the best "sugar free"/zero calorie alternative. If we had some alien vegetation that grew this. Obesity, diabetes and tooth decay would be a thing of the past. Real sugar, completely indigestible to humans.
The article doesn't say it's a new theory. It's about a new study that shows that non-carbon based life might be more common than previoulsy thought:
"It was thought that these sorts of reactions are very rare," Kaçar said in a statement. "We are showing that it's actually far from rare. You just need to look in the right place."
Here is the study, "Assessment of Stoichiometric Autocatalysis across Element Groups", linked in the last paragraph of the article for your enjoyment: https://pubs.acs.org/doi/10.1021/jacs.3c07041
I mean, I can agree that simple autocatalytic reactions can occur with chemistry based on other elements... but it's a stretch to say that suggests "alien life might not be carbon-based". Maybe very, very simple, life-like chemical systems, but life as we know it is defined by large, many-atom molecules, and no other element can do this the the way carbon can (not even silicon, whose bond energy decreases with catentation of more silicon atoms link, which, combined with it's poor ability to form multiple bonds ruins the possibility of silicon-based life). Anything that we can conceivably think of as "life" beyond simple self-reproducing chemical, or bizzare Boltzmann brain-esque systems will have carbon-based chemicals in it.
Thank you! I was going to make this exact point. Autocatalytic reactions are assumed with good reason to be a necessary step on the way from non-life chemicals to life, but they are only one step. Carbon is the only element that can form the basis of the huge variety of chemicals needed for the simplest of life to evolve.
When I was an undergrad, I had professors who made completing arguments that live on other planets would not only be carbon-based, but that it likely would closely resemble life on Earth on molecular, microscopic, and macroscopic levels. Survival of the fit certainly depends upon the environment, but it also must comply with chemistry and physics. I am no expert in theoretical xenobiology, but it provides a strong and fact-based counter to the idea that alien life would by default be wildly different from life on Earth.
I mean that is literally what we're made of. You know those PCR COVID tests? The underlying process just makes DNA/RNA do what they would otherwise do inside the body, outside the body. Put some you-goo through that same process and it just starts replicating all by itself. Everything that makes you unique that's wasn't also a product of your environment is digitally encoded in that double helix, and all it wants or knows how to do is ffuuuuuuuuccckkkkkk
If you want to find alien life you need to know what to look for. If life can exist outside of what we have observed in nature. Then investigating these possibilities will increase the number of markers we have to search for life.
I've always wondered why we should assume that life that evolved separately from us for some reason had to be carbon based. We know (as far as I know) next to nothing about how life arises from non-living chemicals, so as far as I can tell, there's no reason to believe that carbon based life is more common than other life forms (except for the fact that 100% of observed life is carbon based of course).
There's good reason to presume carbon is required. Carbon has some nice, and totally unique properties that allow it to facilitate life.
The most important features to carbon in this context are:
Stable catenation of atoms. Carbon atoms can bond to other carbon atoms in a long chain, and that chain does not become appreciably more reactive. This allows for the construction of very large molecules with specialized mechanical functions.
Ability to form stable multiple bonds. Carbon can form single, double, or triple bonds with itself (and oxygen and nitrogen), which allows carbon-based molecules to have ridgid shapes. Double bonds are found all over the place in life because they allow molecules to have sections that aren't just wiggly noodles of atoms.
Bond stabilities that fall in a kind of "goldilocks zone" where carbon bonds to other atoms are strong enough to resist falling apart, but weak enough to be broken later.
Nearly identical electronegativity to hydrogen. Carbon pulls on the electrons in its bonds about the same amount as hydrogen. This allows it to make stable bonds that are non-polar, which, when used in conjuction with other, more electronegative atoms (particularly oxygen and phosphorus) allow Carbon-containing molecules to be hydrophobic, hydrophilic, or both simultaneously. This property is what allows for complex structures like Lipid bilayers and proteins to be formed.
No other atom, not even silicon, has this set of properties, and it's very hard to imagine how you would make all but the most simplistic verson of life without these.
It's been a long time since I took a biology course, but I think the reason why we believe carbon-based life is more likely is because carbon is far more likely to bond with other elements to form the complex structures nessecary for life at a molecular scale. The only other element that comes close is silicon and it's no where near as good as carbon.
I think it has something to do with the number of electrons in it's outer shell, and how reactive the chemical is. A biochemist could tell you more than me.