https://community.ld4all.com/t/zeitgeist-mind-blowing-documentary/30242 (thread bump! )
Not necessarily. The conditions for fossilization are a lot rarer than most people would think, so fossil evidence is patchy. They look impressive when people can wire them together, great to illustrate/represent what life was probably like way back when, but fossils are not the basis for evolution theory-- taxonomy is the basis.
Since we’re talking about evolution, that gives a loooong lot of time. It isn’t that hard a nudge to get from cells that perform binary fission and mitosis, like you described, to ones that can perform meiosis. Protists, for example-- single celled, or in colonies with no tissue specialization, still do meiosis.
Some life forms that we can extrapolate haven’t changed as much as other evolving life forms-- like barnacles, for example-- primitive life forms, well, some are hermaphroditic. Other varieties of barnacles seem to have found it more favorable to specialize, so they do have what can roughly be considered “males” and “females”… but, the males spend their lives embedded in the females like an organ that’s also a being of its own. Not a big leap to think that the barnacles’ umpt cousins a billion times removed, would be nudged towards a form of species that had full individual beings distinctly specialized into males and females.
The rest of this will just be my fanciful keyboard-mashing. To conform to gender-binary as we understand it, the sexes must evolved together in parallel or there wouldn’t be one to define the other-- so, let’s roughly consider us a hermaphrodite that split. But, if I were to revert evolution theory into a modern creation myth, females seemed to have come first. Human embryos show not to be gender-neutral-- until/unless the sperm’s Y chromosome sparks a masculinization, the embryo follows a female template. Men have nipples. All the DNA in a zygote may be half taken from the mother and half from the father, but the cellular organelles like mitochondria are all taken from the mother.
I define proof as a series of statements used to convince another mathematician that a given statement is true. I suppose Existence Of The Universe isn’t proven, because… it’s an axiom.
At that, Computer Simulation/Dream sounds very appealing.