4 ms·
Embrace and extend: 4) "Room temps" are really comfy for using enzymes to perform energetically infeasible reactions. Too cold and life is too slow to survive
by VLM 11y ago
Embrace and extend:
4) "Room temps" are really comfy for using enzymes to perform energetically infeasible reactions. Too cold and life is too slow to survive and much hotter and you get thermal decomposition faster than life can grow. Its chemically universal... we have the technology to do o-chem and biochem under much weirder conditions than where it actually works best.
5) Trace elements. Despite huge evolutionary pressure and no small amount of experimenting with blood chemistry we're still stuck with red iron based blood. Imagine if you could make blood out of pure protein or even just carbohydrates... But no, every red blooded animal on the planet is stuck refining bioavailable iron, no matter how much of a PITA that is. Would not be surprised if space aliens bleed red like us.
6) Water is awesome for buffer chemistry and this feeds back into your point #1 and my point #4 but homeostasis in the blood or innards in general would be nearly impossible under any other chemistry.
I would not be surprised at all if space aliens were quite familiar with hemoglobin, chlorophyll, some of the cycles like the Krebs cycle. Krebs is very complicated and PITA but most earth life depends on it because it works, if something better were possible, it would have gone extinct half a billion years ago... It would be a fun race, seeing if human and space alien physicists or biochemists start communicating first. My money is on the biochemists, more shared background.
- robbiep 11y agoYour points are good, but despite their entropic advantages they remain limited by the anthropic principle. Other forms are likely possible, just unlikely under our set of circumstances. I would still hazard a guess and say that I would expect carbon based life to be there basis of the lions share of life in the universe though. Regarding the Krebs cycle and other biological feedback cycles, I strongly disagree. It came to dominate at a point where it propagated through all the extant branches of life, but it is by no means the only way life could have decided to do the process of energy production. Once evolution evolves something, it is stuck with that system - no complex biochemical system will evolve into a Krebs replacement whilst Krebs occupies that niche, and evolution isn't going to spit it out of the way!
- bsder 11y ago> Despite huge evolutionary pressure and no small amount of experimenting with blood chemistry we're still stuck with red iron based blood. Careful, this isn't a given. Some tunicates actually concentrate vanadium for oxygen transport. Now, iron is so much more plentiful in the universe that it's likely that it would be pressed into service for oxygen transport, but it isn't given. In addition, life looked very different before the Oxygen Catastrophe, so we have lots of evidence for life without oxygen transport.