4 ms·

Does the fact we can find objects from others systems increases the likelihood of panspermia ?

by seren 8y ago

kekebo 8y ago
Can't find a sound source right now[1] but reportedly some mushroom spores are able to make it into space and withstand its conditions. Edit: thus the more extraterrestrial material makes it to earth the higher the chances that biological material able to withstand the transport conditions makes it here as well. [1] https://www.dopemagazine.com/spores-in-space/ https://www.dopemagazine.com/spores-in-space/
- mmjaa 8y ago
  Tardigrades have been demonstrated capable of surviving in space for extended periods and withstanding extreme conditions. http://www.bbc.co.uk/nature/12855775 http://www.bbc.co.uk/nature/12855775 Then there is the whole recent "Octopus RNA too weird for Earth" thing, which is setting alight the panspermia theses .. myself, personally, I'm tending to think its more and more likely. In my head, in 10 years time, we'll all have this gigantic "there is life in space, and its just like here on Earth only .. hardier .." discussion again and again. Or, maybe we'll still be wondering .. either way, my mind is made up: Octopus are galaxy-wide species, tardigrades too, and we monkeys better be careful we don't join the rest of whatever bipedal species are out there, and step on too many of our little tardigrade/octopus buddies. And, so on. (BTW, don't eat octopus! If the aliens invade, they'll probably massacre you eaters first!)
jcims 8y ago
I think so. Four billion years doesn't seem like enough time to evolve the the sophisticated encoding mechanism of DNA and the level of complexity in individual organisms and the interdependencies they have on each other. I really wish I could find a sort of statistical breakdown of the odds of this all working purely by chance (I'm definitely a fan of evolution and i'm not necessarily invoking woo or God here, just thinking that there are mechanisms at play we don't understand, and a head start would explain a lot for me) This is how my hopelessly naive mind thinks about the problem: Let's round up to say there is 10^15kg of biomass on the planet[1], and there are 10^12 cells per kg[2]. Let's assume that those cells have reproduced every hour for the last 4 billion years (or 35x10^12 hours). That's ~35x10^39 opportunities to pass evolved genetic material to the next generation of cell. One of the organisms with the simplest known genome is mycoplasma genitalium[3], with ~588 genes expressed over 580,070 base pairs. Each base pair has four possible configurations (A,C,G or T). I don't know much of anything, and I definitely don't know the rules around how the base pairs come together. I'm going to naively assume that these base pairs can come together any way they like, and that mutations in DNA express themselves as changes in these sequences. This leaves the DNA of mycoplasma gentalium with 4^580070 or 8.7*10^349236 possible configurations of their DNA. Obviously only a small portion of those are viable. But how do you get from nothing to something of the complexity required to reproduce, and then how do you get from something of that level of simplicity to the genetic diversity that we have on the planet. How many generations from the first living organism are there to current people. Let's say it's a trillion generations. How does random mutation bring you from say a half a million base pairs at the beginning to 3 billion finely tuned base pairs[3] at the end? It just doesn't seem like enough time to me. 1. https://en.wikipedia.org/wiki/Biomass_(ecology) https://en.wikipedia.org/wiki/Biomass_(ecology) 2. https://en.wikipedia.org/wiki/Cell_(biology) https://en.wikipedia.org/wiki/Cell_(biology) 3. https://www.saylor.org/content/BIO_Kimball/users.rcn.com/jkimball.ma.ultranet/BiologyPages/G/GenomeSizes.html https://www.saylor.org/content/BIO_Kimball/users.rcn.com/jki...
- auntienomen 8y ago
  Nature doesn't use arbitrary random sequences of base pairs, any more than we use random sequences of English letters. We can make them, of course, but that's as meaningful as 'bthdkekd'. I am not sure we know enough about the correlation structure of the DNA code to do the calculation you propose.
  - jcims 8y ago
    In a way it is arbitrary, because anything else would imply meaning or intent. Mutations are, as far as we know, arbitrary. Your last point is the thing that has stymied me to date. What is the range of mutation that would allow for a successful offspring and convey (mal)adaptive changes.
    - auntienomen 8y ago
      I use 'arbitrary' in the sense of uniformly random. The point is it's not uniformly random. You can think of reproduction as a random walk in the space of DNA combinations, but it's not a uniform random walk. It has a structure that comes from the biochemical processes which perform the recombinations of DNA. Focusing on mutations ignores this point. (Also, as an aside, it's not settled that mutations occur at random positions. That may be a reasonable starting point, but it's likely that the way DNA folds into nucleosomes/chromatine/chromosomes biases the location of mutations.)
- plopilop 8y ago
  I'm not a biologist, but I'd be surprised that genetic reproduction would be as stable 3 billion years ago than now. I would not be surprised that monocellular beings, which don't need DNA replication to survive, had a more defective cloning system, thus more subject to whichever DNA replication bug. Plus, life took about 1 billion years to emerge. This is huge. The solar system took about the same time to form. Also, life may be extremely slow to appear, but once it's there, progression is quicker. Since the beginning of phanerozoic eon (and Cambrian explosion), a geologic period (Pleistocene, Jurassic, Cambrian...) only lasts a few tens of millions years. I find it very plausible that at the beginning of Cambrian era, a critical step in evolution was reached, allowing a better and faster evolution.

Does the fact we can find objects from others systems increases the likelihood of panspermia ?

by seren 8y ago

Does the fact we can find objects from others systems increases the likelihood of panspermia ?

Can't find a sound source right now[1] but reportedly some mushroom spores are able to make it into space and withstand its conditions. Edit: thus the more extraterrestrial material makes it to earth the higher the chances that biological material able to withstand the transport conditions makes it here as well. [1] https://www.dopemagazine.com/spores-in-space/ https://www.dopemagazine.com/spores-in-space/

mmjaa 8y ago
Tardigrades have been demonstrated capable of surviving in space for extended periods and withstanding extreme conditions. http://www.bbc.co.uk/nature/12855775 http://www.bbc.co.uk/nature/12855775 Then there is the whole recent "Octopus RNA too weird for Earth" thing, which is setting alight the panspermia theses .. myself, personally, I'm tending to think its more and more likely. In my head, in 10 years time, we'll all have this gigantic "there is life in space, and its just like here on Earth only .. hardier .." discussion again and again. Or, maybe we'll still be wondering .. either way, my mind is made up: Octopus are galaxy-wide species, tardigrades too, and we monkeys better be careful we don't join the rest of whatever bipedal species are out there, and step on too many of our little tardigrade/octopus buddies. And, so on. (BTW, don't eat octopus! If the aliens invade, they'll probably massacre you eaters first!)

jcims 8y ago

I think so. Four billion years doesn't seem like enough time to evolve the the sophisticated encoding mechanism of DNA and the level of complexity in individual organisms and the interdependencies they have on each other. I really wish I could find a sort of statistical breakdown of the odds of this all working purely by chance (I'm definitely a fan of evolution and i'm not necessarily invoking woo or God here, just thinking that there are mechanisms at play we don't understand, and a head start would explain a lot for me) This is how my hopelessly naive mind thinks about the problem: Let's round up to say there is 10^15kg of biomass on the planet[1], and there are 10^12 cells per kg[2]. Let's assume that those cells have reproduced every hour for the last 4 billion years (or 35x10^12 hours). That's ~35x10^39 opportunities to pass evolved genetic material to the next generation of cell. One of the organisms with the simplest known genome is mycoplasma genitalium[3], with ~588 genes expressed over 580,070 base pairs. Each base pair has four possible configurations (A,C,G or T). I don't know much of anything, and I definitely don't know the rules around how the base pairs come together. I'm going to naively assume that these base pairs can come together any way they like, and that mutations in DNA express themselves as changes in these sequences. This leaves the DNA of mycoplasma gentalium with 4^580070 or 8.7*10^349236 possible configurations of their DNA. Obviously only a small portion of those are viable. But how do you get from nothing to something of the complexity required to reproduce, and then how do you get from something of that level of simplicity to the genetic diversity that we have on the planet. How many generations from the first living organism are there to current people. Let's say it's a trillion generations. How does random mutation bring you from say a half a million base pairs at the beginning to 3 billion finely tuned base pairs[3] at the end? It just doesn't seem like enough time to me. 1. https://en.wikipedia.org/wiki/Biomass_(ecology) https://en.wikipedia.org/wiki/Biomass_(ecology) 2. https://en.wikipedia.org/wiki/Cell_(biology) https://en.wikipedia.org/wiki/Cell_(biology) 3. https://www.saylor.org/content/BIO_Kimball/users.rcn.com/jkimball.ma.ultranet/BiologyPages/G/GenomeSizes.html https://www.saylor.org/content/BIO_Kimball/users.rcn.com/jki...

auntienomen 8y ago
Nature doesn't use arbitrary random sequences of base pairs, any more than we use random sequences of English letters. We can make them, of course, but that's as meaningful as 'bthdkekd'. I am not sure we know enough about the correlation structure of the DNA code to do the calculation you propose.
- jcims 8y ago
  In a way it is arbitrary, because anything else would imply meaning or intent. Mutations are, as far as we know, arbitrary. Your last point is the thing that has stymied me to date. What is the range of mutation that would allow for a successful offspring and convey (mal)adaptive changes.
  - auntienomen 8y ago
    I use 'arbitrary' in the sense of uniformly random. The point is it's not uniformly random. You can think of reproduction as a random walk in the space of DNA combinations, but it's not a uniform random walk. It has a structure that comes from the biochemical processes which perform the recombinations of DNA. Focusing on mutations ignores this point. (Also, as an aside, it's not settled that mutations occur at random positions. That may be a reasonable starting point, but it's likely that the way DNA folds into nucleosomes/chromatine/chromosomes biases the location of mutations.)
plopilop 8y ago
I'm not a biologist, but I'd be surprised that genetic reproduction would be as stable 3 billion years ago than now. I would not be surprised that monocellular beings, which don't need DNA replication to survive, had a more defective cloning system, thus more subject to whichever DNA replication bug. Plus, life took about 1 billion years to emerge. This is huge. The solar system took about the same time to form. Also, life may be extremely slow to appear, but once it's there, progression is quicker. Since the beginning of phanerozoic eon (and Cambrian explosion), a geologic period (Pleistocene, Jurassic, Cambrian...) only lasts a few tens of millions years. I find it very plausible that at the beginning of Cambrian era, a critical step in evolution was reached, allowing a better and faster evolution.