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.
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.
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.
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.
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I’m pretty sure every 6th grader has this hypothesis when they first hear “carbon based life form”.
… how is this a new theory? The movie evolution made this a central point of the story
Have you read Sphere?
Not yet
How’d it go?
It’s in the backlog, I have some manga I’m reading and a bookclub book first
Enjoy when you have the time!
Head and shoulders for the win
Scientists have theorized this for a while…
okay bruh, how else you gonna synthesize megadalton structures?
deleted by creator
I always thought that it would be more likely for non carbon based life to form
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.
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.
A new study of alien life that we have no idea about? Gotcha.
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.