Great article. These parts of the cell are still mysterious.
Lynn Margulis’s work also suggests that structures like cilia and flagella, that seem like integral parts of the cell, are actually “captured” symbionts that used to be independent organisms.
Lift at that level is pretty weirds. The simple macro view thought in school (a tree with progression from roots to tips) is misleading and barely informative.
Back in the 1990s I spent a long time playing with Tierra (https://en.wikipedia.org/wiki/Tierra_(computer_simulation) ) and actually wrote my own distributed version[1] so it could run over multiple machines (computers were really slow back in 1991), and a simplified instruction set. Now I know that Tierra has a number of serious shortcomings compared to real evolution. Nevertheless it does really surprising things if you let it run long enough and then examine the cells that evolve in the system. Some cells become parasites, some become really large. I also saw really surprising optimizations happen spontaneously that I wouldn't have thought about.
Anyway given that the real thing has been running for 3 or 4 billion years, I'm not surprised that it has generated incredible complexity.
Would you expand a bit on the shortcomings? I'm under the impression artificial life was an attempt in the 90s and after some disappointments fizzled away. Why is simple copying with mutation not sufficient for real evolution? In my naivety I hoped it would lead to digital evolution finding exploits to proliferate across the internet.
One issue with 'evolving' digital life is the primary competition is human assisted digital applications as the primary competition, effectively intelligent design, which is far more powerful ran random chance.
Non-artificial life actually gets massive benefits from horizontal gene transfer which is natures way of letting someone else do all the homework for you.
>According to Thomas S. Ray and others, this may allow for more "open-ended" evolution, in which the dynamics of the feedback between evolutionary and ecological processes can itself change over time (see evolvability), although this claim has not been realized – like other digital evolution systems, it eventually reaches a point where novelty ceases to be created, and the system at large begins either looping or ceases to 'evolve'.
But of course, evolution merely reaches equilibrium, which takes finite time and then stagnates. In real world evolution continues due to change of environment that moves the goalpost of equilibrium, extincts overoptimized species, so evolution can go further. Just add slow change to environment, like ice age or warming.
I find it fascinating how many bizarre, wide gaps we have in evolution where we are left wondering how something could have possibly come into existence at all in the first place.
And clearly, the questions are completely valid. From the most basic "how did life start" to questions like in this article (where did mitochondrion come from?) ... it is very difficult to make sense of. The timescales involved are long, any evidence of the in-between steps is long gone, and simply the odds of these random things occuring would seem to be astronomical.
Taking even just the first premise in this article, that mitochondrion came about due to a cell ingesting another cell, I can see that occuring. Given enough cells, and enough time, I can see it happening repeatedly. I mean, putting a cell in a cell doesn't get you mitochondrion, but you can start with the idea. But how do all these separate isolated occurances, which have no impact on each other in the vast ocean or wherever it is assumed this was taking place, move to the next step?
One single one of those events, then somehow needs not only confer an advantage, but also have the ability then to recreate that "cell within a cell", and then over time that not only needs the survival advantage, it has to undergo further continuous refinement to where, what was a simple merger of two similar things, has become specific internal machinery doing things that confer advantages to the whole.
Just trying to imagine this occuring due to things literally bumping into each other in the ocean already makes my brain start thinking "there's no way". But it is billions of years, there's theoretically a lot of these "primative" cells everywhere, and I just accept that part as seemingly impossible, yet obviously wasn't. And this is all still to try to figure out how only the most basic stuff came about. When you start bringing in complex structures that have to orchestrate with other ones in order to function, it only becomes more difficult and confusing.
At the end of the day, it's obviously evolution. There's literally nothing else it can be. Even if you think it came in on an asteroid, it had to start somewhere. The only other option that I can think of is that none of it is real and the simulation we're living in is glossing over some important details! But I'll stick with evolution.
But it's still very mysterious, to the point it seems to border on the impossible.
Part of what makes this kind of thing difficult to really fathom is the time scales involved - e.coli can reproduce once every 20min or so, yeast can do so every 2 hours or so. 12 replications a day, 4380 replications per year, repeated over a billion years. It all seems phenomenally unlikely, but the combination of an unfathomable number of repetitions and even a small evolutionary thumb on the scale can take you an enormous distance.
The "not stranger then we suppose but stranger then we can suppose" part for me isn't the how did life start or how did that eukaryotes evolve from prokaryotes. Those are both genuinely mysterious.
The thing that gets me is why it was easier to go from no life to life.
If you said it took 2 billion years for life to emerge from inorganic molecules but 300 million years after that we had eukaryotes then I'd say, that seems about right - I wonder how it happened?
Tell me that (as I understand to be the case) life pops up a couple of hundred million years after it's possible to have life on earth - and then several billion years go by before you get eukaryotes then I'm really left scratching my head.
I'm not saying mitochondria aren't amazing but the leap seems closer to me to the evolution of warm blooded animals from cold blooded ones. Life from nothing seems fantastically more complicated.
I'm generally down on life's origins being an off-earth thin but ... sometimes I wonder.
I’d suggest the book Life Ascending. It talks about how certain major jumps in complexity occurs. It directly addresses the “bumping in the ocean” you mention — according to the book the likely explanation was these initial reactions occurred in local environments around certain types of thermal vents that were constrained by small geologic features. Interesting read.
I'm guessing at the start it was incredibly easy to stick things together, like two Lego pieces. After a few thousand years and a few interesting Lego builds, some with interchangeable brick complexes with one another, a great calamity destroys the majority of those builds, leading a sparse minority of builds which seem to have legacy interchangeable brick complexes still for reasons unknown to us
One thing I didn’t see mentioned in this article, that I thought was one of the major motivators for realizing that mitochondria originally came from outside the body, is that mitochondria have their own DNA independent of the cell’s nuclear DNA. But I wasn’t aware that any other animal organelles do (chloroplasts in plants do, and those are also assumed to have originally been an independent bacteria).
The DNA in mitochondria has a slightly different genetic code compared to DNA in the nucleus, which is evidence that mitochondria were once free living organisms, and they separated from other organisms before the genetic code was fully established. A fascinating glimpse of a lost world.
The article doesn’t mention that nuclei, mitochondria, and chloroplasts all have double membranes. If I had to guess, I would bet that those are the organelles that were formed by endosymbiosis.
I take this fact as suggesting that there may be more to the frequency illusion than just illusion.
How it feels is similar to like what you get when you run GTA on a system with finite VRAM. - The game uses the same assets over and over again, so you see the same cars and pedestrians too frequently to be random.
Can't really wrap my head around it though. It just seems unreasonable to demand that our reality has infinite capacity for complexity.
Many of them have properties of being self similar. This is also a pattern we see in biological life. Life is primarily assembled from a limited subset of all elements. Carbon, hydrogen, oxygen, nitrogen being most common by weight. There are a few common means of assembling those molecules using the least energy possible, so those will be the ones we see most, and higher energy activations should be exponentially less common.
Lynn Margulis’s work also suggests that structures like cilia and flagella, that seem like integral parts of the cell, are actually “captured” symbionts that used to be independent organisms.
Lift at that level is pretty weirds. The simple macro view thought in school (a tree with progression from roots to tips) is misleading and barely informative.