7 ms·

All life is equally ancient and the pressure of evolution has molded all life for equal amounts of time. (But not necessarily to equal extents as the ability t

by enkid 3y ago

All life is equally ancient and the pressure of evolution has molded all life for equal amounts of time. (But not necessarily to equal extents as the ability to adapt is itself an evolutionary process.) What we may find is an ancient branch, with some features preserved we don't know about, but also some features adapted for the extreme environment.

not_alexb 3y ago
This seems like such a huge reductive statement to make. Suppose: on some planet untouched by man, there was a species identical to a species on earth, would you say they share the same ancestor? Suppose: I generated an organism (that already exists) starting from raw chemistry, would that share the same ancestor as the one that already exists?
- AlbertCory 3y ago
  The original question was about ancient life still existing on Earth, not hypotheticals.
  - not_alexb 3y ago
    And the answer gave such certainty to what ancient life would be like that my hypotheticals should be able to be answered (in the same context) with just as much certainty. It's trivial to apply my hypotheticals to models in which life didn't all descend from a common ancestor.
    - _a_a_a_ 3y ago
      > It's trivial to apply my hypotheticals to models in which life didn't all descend from a common ancestor We don't have such a thing to our knowledge so it's not trivial. If you still feel it is, do the application yourself - it's trivial after all.
      - not_alexb 3y ago
        I don't think you understand what I'm saying. You can arbitrarily create models of earth life that didn't have a common ancestor via "my" hypotheticals which are just as valid as univeral common ancestor (which predominantly features: there is something common in all life, so all life must have came from the same place; obviously this is a gross oversimplification but that's what we're dealing with in the answer)
        _a_a_a_ 3y ago
        > You can arbitrarily create models of earth life that didn't have a common ancestor I'm finding it very difficult to understand what you mean by "models of life". Actually I have no idea. What does this phrase even mean?
    - anonymouskimmer 3y ago
      You're invoking god and magic (i.e. sufficiently implausible coincidence and sufficiently advanced technology). Yes, god and magic can render most descriptions of how the universe operates inadequate.
      - not_alexb 3y ago
        I am absolutely not. There are lines I didn't draw for the sake of time. Re: think about how you could translate my hypotheticals into how nature could do that on its own (obviously over a much longer course of time and fortuitous conditions).
        anonymouskimmer 3y ago
        1) I presumed that the person you originally replied to was speaking of terrestrial life when they wrote "all life". 2) There are thoughts that life on Earth, presuming it started on Earth and wasn't seeded from meteorites, may have started from multiple populations. But it's presumed that if it did so those multiple populations were either out-competed by one population, or sufficiently alike that they effectively merged in their descendants. At any rate, at this point, all life that we have so far detected shares similar enough features to presume a common origin. This includes incredibly separate lineages such as the bacteria and archaea. Would you consider modern computers to be descended from IBM mainframes? Someone building a duplicate lifeform from parts based on existing knowledge and existing lifeforms does not negate that those existing lifeforms evolved into form since the beginning of terrestrial life. Your work is standing on preexisting evolutionary knowledge, processes, and a chain of life, even if it technically replaces biological reproduction with a human engineer. From a dialectical point of view you're effectively invoking god to nitpick. If you believe you aren't you're going to have to spell it out for me.
- fikama 3y ago
  it may not share common ancestor, but from your comment I assume it could reproduce with earth based counterpart. Thus it would be considered by the most popular definition to be the same species.
- sharpneli 3y ago
  1) Probability of that is so miniscule as to be nonexistent. I’d suspect foul play at that point. As in someone just transporting the animal there. You can’t really get identical DNA on earth. It’s to be expected that it would be even harder if there are no common ancestors. 2) Yes. In order to make that you need to basically fully understand the organism in question. All of it’s properties are the same and product of the same evolutionary history by the virtue of you just looking at the existing creature and making an 1:1 copy
  - dryrun 3y ago
    Funnily enough, I have the opposite view: given the amount of stars and of earth like planets in the universe, probabilistically speaking there is bound to be a random chance where two instances of life have the same DNA without ever being in contact. Disclaimer: I'm bad at maths and good at dreaming.
    - anonymouskimmer 3y ago
      :D Yes, you are. :) The bare simplest genomes are viral genomes about 1000 bases long. These can only operate in environments created by more complex genomes. But even taking them, the theoretical diversity in a genome 1000 bases long, using the 4 canonical nucleic acids, is 4^1000. The number of atoms in the entire universe is around 10^80 (https://educationblog.oup.com/secondary/maths/numbers-of-atoms-in-the-universe https://educationblog.oup.com/secondary/maths/numbers-of-ato... ). There's a lot of complexity here: other life may use other nucleotides; those atoms and bases are constantly being rearranged; many base changes are relatively silent - they don't materially matter; etcetera. I don't know how to calculate all of the rest of these factors, but I think the odds are more than astronomical.
      - _Microft 3y ago
        > I don't know how to calculate all of the rest of these factors, but I think the odds are more than astronomical. OK, let's do this then. Here we will approximate the ratio 4^1000/10^80: x = 4^1000 / 10^80 ln(x) = 1000 * ln(4) - 80 * ln(10) // You know your logarithm calculation rules, right? Right?! ln(x) = 1386 - 184 // Who needs decimal places anyways? ;) ln(x) = 1202 x = 10^522
- enkid 3y ago
  If it was truly identical, i.e. same anatomical and biological features, it would be proof that something had transported them there, and would therefore be a branch of life from Earth.
  - not_alexb 3y ago
    If it was truly an identical species and it was the simplest form of life possible, you're saying that it could only be transported from earth? That seems a bit shaky. You don't think the same factors that created the first lifeform on earth couldn't naturally be reproduced anywhere else to create that same lifeform?
    - retrac 3y ago
      Taking the premise rather literally, it would mean, for example, that the DNA of the organism would be typical for a member of its species on Earth. The odds of hundreds of millions of bits of genetic information coincidentally being the same are, if you'll pardon the expression, astronomical.
      - Retric 3y ago
        Astronomical is if anything understating how unlikely that would be.
      - NalNezumi 3y ago
        This seems like a silly premise though. It's like saying a standard opener move in a boardgame is unlikely because there's a lot of other moves available. It's standard move because the game have an optimal set of opener move to achieve victory. So if another planet with similar environment exist, the range of solutions for self preservation goal might be a tiny subset out of the hundreds of millions of bits of genetic information.

by enkid 3y ago

not_alexb 3y ago

This seems like such a huge reductive statement to make. Suppose: on some planet untouched by man, there was a species identical to a species on earth, would you say they share the same ancestor? Suppose: I generated an organism (that already exists) starting from raw chemistry, would that share the same ancestor as the one that already exists?

AlbertCory 3y ago
The original question was about ancient life still existing on Earth, not hypotheticals.
- not_alexb 3y ago
  And the answer gave such certainty to what ancient life would be like that my hypotheticals should be able to be answered (in the same context) with just as much certainty. It's trivial to apply my hypotheticals to models in which life didn't all descend from a common ancestor.
  - _a_a_a_ 3y ago
    > It's trivial to apply my hypotheticals to models in which life didn't all descend from a common ancestor We don't have such a thing to our knowledge so it's not trivial. If you still feel it is, do the application yourself - it's trivial after all.
    - not_alexb 3y ago
      I don't think you understand what I'm saying. You can arbitrarily create models of earth life that didn't have a common ancestor via "my" hypotheticals which are just as valid as univeral common ancestor (which predominantly features: there is something common in all life, so all life must have came from the same place; obviously this is a gross oversimplification but that's what we're dealing with in the answer)
      - _a_a_a_ 3y ago
        > You can arbitrarily create models of earth life that didn't have a common ancestor I'm finding it very difficult to understand what you mean by "models of life". Actually I have no idea. What does this phrase even mean?
  - anonymouskimmer 3y ago
    You're invoking god and magic (i.e. sufficiently implausible coincidence and sufficiently advanced technology). Yes, god and magic can render most descriptions of how the universe operates inadequate.
    - not_alexb 3y ago
      I am absolutely not. There are lines I didn't draw for the sake of time. Re: think about how you could translate my hypotheticals into how nature could do that on its own (obviously over a much longer course of time and fortuitous conditions).
      - anonymouskimmer 3y ago
        1) I presumed that the person you originally replied to was speaking of terrestrial life when they wrote "all life". 2) There are thoughts that life on Earth, presuming it started on Earth and wasn't seeded from meteorites, may have started from multiple populations. But it's presumed that if it did so those multiple populations were either out-competed by one population, or sufficiently alike that they effectively merged in their descendants. At any rate, at this point, all life that we have so far detected shares similar enough features to presume a common origin. This includes incredibly separate lineages such as the bacteria and archaea. Would you consider modern computers to be descended from IBM mainframes? Someone building a duplicate lifeform from parts based on existing knowledge and existing lifeforms does not negate that those existing lifeforms evolved into form since the beginning of terrestrial life. Your work is standing on preexisting evolutionary knowledge, processes, and a chain of life, even if it technically replaces biological reproduction with a human engineer. From a dialectical point of view you're effectively invoking god to nitpick. If you believe you aren't you're going to have to spell it out for me.
fikama 3y ago
it may not share common ancestor, but from your comment I assume it could reproduce with earth based counterpart. Thus it would be considered by the most popular definition to be the same species.
sharpneli 3y ago
1) Probability of that is so miniscule as to be nonexistent. I’d suspect foul play at that point. As in someone just transporting the animal there. You can’t really get identical DNA on earth. It’s to be expected that it would be even harder if there are no common ancestors. 2) Yes. In order to make that you need to basically fully understand the organism in question. All of it’s properties are the same and product of the same evolutionary history by the virtue of you just looking at the existing creature and making an 1:1 copy
- dryrun 3y ago
  Funnily enough, I have the opposite view: given the amount of stars and of earth like planets in the universe, probabilistically speaking there is bound to be a random chance where two instances of life have the same DNA without ever being in contact. Disclaimer: I'm bad at maths and good at dreaming.
  - anonymouskimmer 3y ago
    :D Yes, you are. :) The bare simplest genomes are viral genomes about 1000 bases long. These can only operate in environments created by more complex genomes. But even taking them, the theoretical diversity in a genome 1000 bases long, using the 4 canonical nucleic acids, is 4^1000. The number of atoms in the entire universe is around 10^80 (https://educationblog.oup.com/secondary/maths/numbers-of-atoms-in-the-universe https://educationblog.oup.com/secondary/maths/numbers-of-ato... ). There's a lot of complexity here: other life may use other nucleotides; those atoms and bases are constantly being rearranged; many base changes are relatively silent - they don't materially matter; etcetera. I don't know how to calculate all of the rest of these factors, but I think the odds are more than astronomical.
    - _Microft 3y ago
      > I don't know how to calculate all of the rest of these factors, but I think the odds are more than astronomical. OK, let's do this then. Here we will approximate the ratio 4^1000/10^80: x = 4^1000 / 10^80 ln(x) = 1000 * ln(4) - 80 * ln(10) // You know your logarithm calculation rules, right? Right?! ln(x) = 1386 - 184 // Who needs decimal places anyways? ;) ln(x) = 1202 x = 10^522
enkid 3y ago
If it was truly identical, i.e. same anatomical and biological features, it would be proof that something had transported them there, and would therefore be a branch of life from Earth.
- not_alexb 3y ago
  If it was truly an identical species and it was the simplest form of life possible, you're saying that it could only be transported from earth? That seems a bit shaky. You don't think the same factors that created the first lifeform on earth couldn't naturally be reproduced anywhere else to create that same lifeform?
  - retrac 3y ago
    Taking the premise rather literally, it would mean, for example, that the DNA of the organism would be typical for a member of its species on Earth. The odds of hundreds of millions of bits of genetic information coincidentally being the same are, if you'll pardon the expression, astronomical.
    - Retric 3y ago
      Astronomical is if anything understating how unlikely that would be.
    - NalNezumi 3y ago
      This seems like a silly premise though. It's like saying a standard opener move in a boardgame is unlikely because there's a lot of other moves available. It's standard move because the game have an optimal set of opener move to achieve victory. So if another planet with similar environment exist, the range of solutions for self preservation goal might be a tiny subset out of the hundreds of millions of bits of genetic information.