3 ms·
It's all just chemistry, and the chemistry is extremely conservative all the way back to the first eukaryotes. Once our kind of life figures out a way to do som
by jaggederest 2y ago
It's all just chemistry, and the chemistry is extremely conservative all the way back to the first eukaryotes. Once our kind of life figures out a way to do something it's very uncommon that the fundamental pathways change - not by any means impossible.
Cells that have novel things happen to them nearly always die. Others become cancer, which is a career-limiting move for multicellular life at least. So the process of changes to basic chemistry of life is very slow. That's why omnivores can eat almost anything and be fine with it - imagine if different branches of plants and animals had really novel things in them, like a critter with nerve gas for a circulatory fluid.
There's been some discussion of mirror bacteria lately, which have opposite chirality in all their molecules, which would be substantially problematic since we really don't have defenses against that kind of thing. That just shows the degree to which you'd have to rejigger biochemistry to get a truly whole new thing going on.
- Eddy_Viscosity2 2y agoLike all plants that produce sugar produce left-handed sugar molecules. And all animals that can digest sugar can only digest left-handed sugar molecules. There was no meeting, this is just the way it worked out.
- KyleSanderson 2y agoThe meeting was the animals who evolved to not be able to consume this, lived in more harsh conditions than those that had the readily available sugar. Evolution.
- malux85 2y agoYeah, having the reward function baked into the runtime is a sure way to eliminate any nonsense!
- alphan0n 2y agoOur physiology can still interact with other chiral molecules though right? Just for example, both the stereoisomers, dextro/levo amphetamine, in my limited understanding of pharmacological interactions, cause a reaction. One being a powerful stimulant/psychotropic that can cause psychosis, the other benign enough to be sold over the counter as a nasal decongestant with stimulating effects, but orders of magnitude weaker.
- throwup238 2y agoYou are correct. Protein chirality determines which direction they twist when they fold but the binding sites are all made up of the same functional groups, just arranged differently. Realistically they have to be compatible because chirality is enforced by a D-handed chiral checkpoint protein that preferentially binds to L-amino acids, excluding the D-amino acids. All living organisms use the “wrong” isomer to make sure only the “right” isomer is used in protein synthesis. The amino acid cysteine is also present in both forms in mammals, so it extends to small molecules too.
- scns 2y ago> One being a powerful stimulant/psychotropic that can cause psychosis It can cause way more than psychosis. ODing on dextroamphetamine can kill you.
- elcritch 2y agoI don’t think mirror bacteria would do that well. They’d have to survive all the other handed chemicals already out there and to be able to use the other handed proteins and sugars for food to become pests. Furthermore immune systems can create antibodies which bind to arbitrary proteins as I understand it.
- mmooss 2y ago> ... chemistry is extremely conservative all the way back to the first eukaryotes. Once our kind of life figures out a way to do something it's very uncommon that the fundamental pathways change Why don't most effects cross species barriers? Plenty of viruses, for example, affect some species but not others. When developing medical treatments, I thought that researchers had to carefully choose animal species analogs to humans for testing, and even then it was very unreliable.
- snapplebobapple 2y agoso do you think interacting with aliens is possible given the chemistry side of things? The more I think about it the more concerned I am that that will end badly because our microbiology will act benign until it figures a way to use the foreign life as a food source and then boom one of us dies off.
- jaggederest 2y agoWell, if they evolved differently then maybe not. But they'll have the same fundamental building blocks in terms of atoms, and there's a limited amount of energetically favorable ways to slice that particular bread. I would be surprised if we ran into any extraterrestrial life that wasn't carbon based. They may choose a different chirality but there's very little chemically as versatile as carbon carbon bonds. And based on just prevalence levels in the universe carbon-hydrogen-oxygen-nitrogen is a pretty solid bet evolutionarily.
- snapplebobapple 2y agowe aren't made of carbon directly though, we are made of amino acids that are made from carbon and a few other things (plus polysacharides and a bunch of fatty acids), so I wouldn't exactly say we are made of the same fundamental building blocks, as I expect there is way more than just our set of amino acids that will work (I would expect a number of different grouping of amino acids to work as separate groups and how the first proto amino acids happen to be put to use by chance to determine which grouping then goes on to evolve further and dominate because if you have to break something down and rebuild it as what you need it is way costlier than just dissasembling to aminos and reassembling so given enough time one should becomethe monopoly)