8 ms·

There have been several bottlenecks, the worst one was pre-homosapien (~1000 individuals for 100k years): https://en.wikipedia.org/wiki/Population_bottleneck ht

There have been several bottlenecks, the worst one was pre-homosapien (~1000 individuals for 100k years): https://en.wikipedia.org/wiki/Population_bottleneck https://en.wikipedia.org/wiki/Population_bottleneck. It is remarkable to imagine that every person alive now, or that's ever been alive, is descended from this same tiny group of beings. And all of this drama occurs in a remote spec of dust orbiting and average star of an average galaxy of 100B stars, among 100B visible galaxies. Even if we had Star Trek level tech, we'd still be approximately as insignificant.

paulpauper 1y ago
The range is 100,000 to 1000 individuals. This is a factor of 100.. If you take the midpoint ,it's 50k, which is not as bad.
- cl3misch 1y ago
  I think the multiplicative midpoint (i.e geometric mean) is more sensible for such a large range, which gives 10k. Still not as bad!
- ashoeafoot 1y ago
  But what kept them hovering there for a thousand years? What besieged our ancestors until they developed something to break that siege ?
  - Retric 1y ago
    The people we descended from could be different from the entire population at that time. A beneficial mutation followed by rapidly outcompeting other populations might look similar.
  - deafpolygon 1y ago
    The theory is that it was like that for over 100 thousand years. Not just a thousand.
    - ashoeafoot 1y ago
      So solitary confinement into a bottle besieged by quasi equal predators unlocks superpowers ?
lo_zamoyski 1y ago
Why would size determine significance? And what is significance anyway? What determines whether something is significant?
- voidspark 1y ago
  Size determines significance by definition of a population bottleneck
- kbelder 1y ago
  Statistically, size or quantity is a major part of significance. But that's not really the sense in which 'significant' is being used here... it's being used as a synonym of 'important' or 'meaningful'. In those terms, you have to ask the question, 'significant to whom?' Significance doesn't exist outside of somebody to attach meaning to it. Most often, the answer is 'to me, the guy making the observation.' In that sense, that tiny speck of dust in our corner of the galaxy is very significant. At least to me.
- ashoeafoot 1y ago
  The self repair forces of the ego selecting the tale with the highest praise for me, the chosen one, living at the end of time, made in gods image.
jowea 1y ago
I mean, all of non-viral life is descended from a single organism, right? I find that even more remarkable.
- eddd-ddde 1y ago
  I think that's only true assuming no other life has appeared in any other place of the universe.
  - tehlike 1y ago
    Or multiples of organisms spawned in earth simultaneously.
    - NoMoreNicksLeft 1y ago
      Life has probably spawned abiogenically dozens of times. Lifeforms today are syncretic... they started out separately and merged into what we have now. See this with various endosymbiotes like mitochondria. There's probably also some trees of life currently on Earth that are completely separate from us hiding in plain sight (so to speak).
      - tehlike 1y ago
        Most probably! With same reasoning, it's not hard to think we are not alone in this universe, given the sheer scale of cosmos.
- kadoban 1y ago
  It seems quite likely that this isn't actually fundamentally true, because the real story was a mess. If you look at bacteria even, there's a lot of genetic transfer beyond just strict parent/child relationships either just directly or via viruses or other things I'm sure I've never heard of. The earliest life was probably more like some kind of soup of self-replicating things, closer to a chemical reaction than biological, and then it would have been kind of a sliding scale over a long period of time before we get to anything that really looks that much like "<this> organism begat <that> organism". The entire concept of organisms themselves are an abstraction over the truth, that kind of works for today's world, but probably less worked when things were new and interesting and messy.
jiggawatts 1y ago
Note that there is a big difference between "we are all descended from X individuals Y years ago" and "there was X individuals alive Y years ago"! There were many more humans alive at all points in time than the "genetic bottlenecks" suggest. It's just that their lineage ended at some point later, and wasn't passed on to modern humans.
- deepsun 1y ago
  I don't see how it follows that there were many more humans. Math says that all people eventually become descendants of every single individual (kinda "diffusion"), or die off completely. Say, there were not "many more", but just like 15% more. Like 1150 alive, and descendants of 1000 of them did not die off completely. Sounds plausible.
  - BurningFrog 1y ago
    Not everyone has children. Even more don't have any surviving grandchildren. This is true even today, but back in the original "state of nature", death for all sorts of reasons was way more common than today. Run that through a few thousand generations, with wars, genocides and epidemics, and you get big numbers.
    - deepsun 1y ago
      Yes, but people had way more children. E.g my grand-grandparents had many kids, and counting only surviving ones is still 3x more than my grandparents. Combined with much earlier parenthood, humans were "diffusing" their genes way faster than we do before dying earlier.
  - dathinab 1y ago
    Ignoring that it might be related to stations where idk. most people can't have children (or they at lest won't survive). The other options is that there can be while groups of humans in a distant place alive at the same time, but they didn't survive long term and didn't re-mix with the "bottleneck group" at lest not in a way detectable genetically (idk. how precises the methods in question are). The point here isn't that a genetic bottle neck implies the presence of other humans, but that it doesn't say that there can't have been other humans, just that other humans genes didn't carry forward until today.

paulpauper 1y ago

The range is 100,000 to 1000 individuals. This is a factor of 100.. If you take the midpoint ,it's 50k, which is not as bad.

cl3misch 1y ago
I think the multiplicative midpoint (i.e geometric mean) is more sensible for such a large range, which gives 10k. Still not as bad!
ashoeafoot 1y ago
But what kept them hovering there for a thousand years? What besieged our ancestors until they developed something to break that siege ?
- Retric 1y ago
  The people we descended from could be different from the entire population at that time. A beneficial mutation followed by rapidly outcompeting other populations might look similar.
- deafpolygon 1y ago
  The theory is that it was like that for over 100 thousand years. Not just a thousand.
  - ashoeafoot 1y ago
    So solitary confinement into a bottle besieged by quasi equal predators unlocks superpowers ?

lo_zamoyski 1y ago

Why would size determine significance? And what is significance anyway? What determines whether something is significant?

voidspark 1y ago
Size determines significance by definition of a population bottleneck
kbelder 1y ago
Statistically, size or quantity is a major part of significance. But that's not really the sense in which 'significant' is being used here... it's being used as a synonym of 'important' or 'meaningful'. In those terms, you have to ask the question, 'significant to whom?' Significance doesn't exist outside of somebody to attach meaning to it. Most often, the answer is 'to me, the guy making the observation.' In that sense, that tiny speck of dust in our corner of the galaxy is very significant. At least to me.
ashoeafoot 1y ago
The self repair forces of the ego selecting the tale with the highest praise for me, the chosen one, living at the end of time, made in gods image.

jowea 1y ago

I mean, all of non-viral life is descended from a single organism, right? I find that even more remarkable.

eddd-ddde 1y ago
I think that's only true assuming no other life has appeared in any other place of the universe.
- tehlike 1y ago
  Or multiples of organisms spawned in earth simultaneously.
  - NoMoreNicksLeft 1y ago
    Life has probably spawned abiogenically dozens of times. Lifeforms today are syncretic... they started out separately and merged into what we have now. See this with various endosymbiotes like mitochondria. There's probably also some trees of life currently on Earth that are completely separate from us hiding in plain sight (so to speak).
    - tehlike 1y ago
      Most probably! With same reasoning, it's not hard to think we are not alone in this universe, given the sheer scale of cosmos.
kadoban 1y ago
It seems quite likely that this isn't actually fundamentally true, because the real story was a mess. If you look at bacteria even, there's a lot of genetic transfer beyond just strict parent/child relationships either just directly or via viruses or other things I'm sure I've never heard of. The earliest life was probably more like some kind of soup of self-replicating things, closer to a chemical reaction than biological, and then it would have been kind of a sliding scale over a long period of time before we get to anything that really looks that much like "<this> organism begat <that> organism". The entire concept of organisms themselves are an abstraction over the truth, that kind of works for today's world, but probably less worked when things were new and interesting and messy.

jiggawatts 1y ago

Note that there is a big difference between "we are all descended from X individuals Y years ago" and "there was X individuals alive Y years ago"! There were many more humans alive at all points in time than the "genetic bottlenecks" suggest. It's just that their lineage ended at some point later, and wasn't passed on to modern humans.

deepsun 1y ago
I don't see how it follows that there were many more humans. Math says that all people eventually become descendants of every single individual (kinda "diffusion"), or die off completely. Say, there were not "many more", but just like 15% more. Like 1150 alive, and descendants of 1000 of them did not die off completely. Sounds plausible.
- BurningFrog 1y ago
  Not everyone has children. Even more don't have any surviving grandchildren. This is true even today, but back in the original "state of nature", death for all sorts of reasons was way more common than today. Run that through a few thousand generations, with wars, genocides and epidemics, and you get big numbers.
  - deepsun 1y ago
    Yes, but people had way more children. E.g my grand-grandparents had many kids, and counting only surviving ones is still 3x more than my grandparents. Combined with much earlier parenthood, humans were "diffusing" their genes way faster than we do before dying earlier.
- dathinab 1y ago
  Ignoring that it might be related to stations where idk. most people can't have children (or they at lest won't survive). The other options is that there can be while groups of humans in a distant place alive at the same time, but they didn't survive long term and didn't re-mix with the "bottleneck group" at lest not in a way detectable genetically (idk. how precises the methods in question are). The point here isn't that a genetic bottle neck implies the presence of other humans, but that it doesn't say that there can't have been other humans, just that other humans genes didn't carry forward until today.