5 ms·

This is assuming independent genesis. Panspermia has a lot of merit.

by willis936 5y ago

machiaweliczny 5y ago
I think terdigrades might already be alien. How they evolved on earth?
- superduperycomb 5y ago
  I believe if you look at their genetics they fit snugly within the tree of life
  - andruby 5y ago
    What would be the odds that other planets/habitats have a similar "tree of life"? I don't know. Given the huge number of similarities in DNA, I'd say it's extremely small.
  - bumby 5y ago
    I don’t want to speak for the OP but I read their comment as “why did they evolve certain features that wouldn’t have be reasonable given the evolutionary pressures of earth?” E.g., their ability to survive high levels of radiation or vacuum. There’s some speculation that a large amount of their genetics were transferred from other animals.[1] I wonder how much this muddles the tracing through the evolutionary tree. [1] https://www.pnas.org/content/112/52/15976.abstract https://www.pnas.org/content/112/52/15976.abstract
    - someguyorother 5y ago
      > E.g., their ability to survive high levels of radiation or vacuum. If I recall correctly, the tardigrades (and extremophiles like D. radiodurans) have evolved to handle damage brought on by desiccation. As a fortunate side-effect, this general robustness also protects against radiation.
  - rozab 5y ago
    This is one of my favourite websites, and I share it all the time: https://www.onezoom.org/life.html/@=111445?img=best_any&anim=flight#x-954,y34,w6.8520 https://www.onezoom.org/life.html/@=111445?img=best_any&anim... (hopefully that links to the right place)
- stefs 5y ago
  tardigrades might have some very cool properties, but nothing out of the ordinary.
echelon 5y ago
Panspermia is fascinating conjecture. The preferred chirality of organic molecules could absolutely have arisen by chance, but it's an interesting to see this in meteorites. On the unrelated subject of handedness, I saw an interesting thread on Twitter today [1] speaking about how we're starting to synthesize reverse chirality polymers and enzymes, most notably DNA and replication enzymes. There are a lot of interesting implications. You can't get rid of L-DNA without reverse DNase, leading to an accumulation of information and transcription. So they need to remake all the enzyme steroisomers. That alone is interesting, but you can take it further to the limit and produce reverse biology that synthesizes reverse sugars that can't be metabolized by much of extant life [2]. Suddenly a lab-escaped reverse autotroph can out-compete all of us right-handed lifeforms because nothing can eat them. Bacteria, plankton, the entire food web collapses. When we have nothing left to fish or farm, we die too. Never thought nanotech's grey goo was plausible. Now I see something that rhymes with it, and I could see it happening within our lifetimes. It'd make a crazy MAD bioweapon on par with or potentially worse than nukes. Wild tangent, sorry. [1] https://twitter.com/eigenrobot/status/1420952351968432130 https://twitter.com/eigenrobot/status/1420952351968432130 [2] https://twitter.com/prawncis/status/1420982623048925187 https://twitter.com/prawncis/status/1420982623048925187
- wizzwizz4 5y ago
  > because nothing can eat them But I assume they're not immune-invulnerable.
  - echelon 5y ago
    Where did the reverse viruses that can bind to their cellular receptors and co-opt their reverse cellular metabolism evolve? To be clear, evolution of viruses is probably inevitable. But on what time scale does it take for them to arrive ex nihilo? Millennia? Longer?
- radicaldreamer 5y ago
  I'm getting similar vibes to out of control gene drives created with crispr...
- 5y ago
imglorp 5y ago
Yes and there are two types of panspermia. The first type is incidental: we've already encountered meteorites from Mars and the Moon, for example, so it's not hard to imagine life bearing material arriving that way. The second would be intentional: either ET seeds planets or merely visits them with contaminated boots or probes. Either way, we would pick up some DNA from offworld.

This is assuming independent genesis. Panspermia has a lot of merit.

machiaweliczny 5y ago

I think terdigrades might already be alien. How they evolved on earth?

superduperycomb 5y ago
I believe if you look at their genetics they fit snugly within the tree of life
- andruby 5y ago
  What would be the odds that other planets/habitats have a similar "tree of life"? I don't know. Given the huge number of similarities in DNA, I'd say it's extremely small.
- bumby 5y ago
  I don’t want to speak for the OP but I read their comment as “why did they evolve certain features that wouldn’t have be reasonable given the evolutionary pressures of earth?” E.g., their ability to survive high levels of radiation or vacuum. There’s some speculation that a large amount of their genetics were transferred from other animals.[1] I wonder how much this muddles the tracing through the evolutionary tree. [1] https://www.pnas.org/content/112/52/15976.abstract https://www.pnas.org/content/112/52/15976.abstract
  - someguyorother 5y ago
    > E.g., their ability to survive high levels of radiation or vacuum. If I recall correctly, the tardigrades (and extremophiles like D. radiodurans) have evolved to handle damage brought on by desiccation. As a fortunate side-effect, this general robustness also protects against radiation.
- rozab 5y ago
  This is one of my favourite websites, and I share it all the time: https://www.onezoom.org/life.html/@=111445?img=best_any&anim=flight#x-954,y34,w6.8520 https://www.onezoom.org/life.html/@=111445?img=best_any&anim... (hopefully that links to the right place)
stefs 5y ago
tardigrades might have some very cool properties, but nothing out of the ordinary.

echelon 5y ago

Panspermia is fascinating conjecture. The preferred chirality of organic molecules could absolutely have arisen by chance, but it's an interesting to see this in meteorites. On the unrelated subject of handedness, I saw an interesting thread on Twitter today [1] speaking about how we're starting to synthesize reverse chirality polymers and enzymes, most notably DNA and replication enzymes. There are a lot of interesting implications. You can't get rid of L-DNA without reverse DNase, leading to an accumulation of information and transcription. So they need to remake all the enzyme steroisomers. That alone is interesting, but you can take it further to the limit and produce reverse biology that synthesizes reverse sugars that can't be metabolized by much of extant life [2]. Suddenly a lab-escaped reverse autotroph can out-compete all of us right-handed lifeforms because nothing can eat them. Bacteria, plankton, the entire food web collapses. When we have nothing left to fish or farm, we die too. Never thought nanotech's grey goo was plausible. Now I see something that rhymes with it, and I could see it happening within our lifetimes. It'd make a crazy MAD bioweapon on par with or potentially worse than nukes. Wild tangent, sorry. [1] https://twitter.com/eigenrobot/status/1420952351968432130 https://twitter.com/eigenrobot/status/1420952351968432130 [2] https://twitter.com/prawncis/status/1420982623048925187 https://twitter.com/prawncis/status/1420982623048925187

wizzwizz4 5y ago
> because nothing can eat them But I assume they're not immune-invulnerable.
- echelon 5y ago
  Where did the reverse viruses that can bind to their cellular receptors and co-opt their reverse cellular metabolism evolve? To be clear, evolution of viruses is probably inevitable. But on what time scale does it take for them to arrive ex nihilo? Millennia? Longer?
radicaldreamer 5y ago
I'm getting similar vibes to out of control gene drives created with crispr...
5y ago

imglorp 5y ago

Yes and there are two types of panspermia. The first type is incidental: we've already encountered meteorites from Mars and the Moon, for example, so it's not hard to imagine life bearing material arriving that way. The second would be intentional: either ET seeds planets or merely visits them with contaminated boots or probes. Either way, we would pick up some DNA from offworld.