There appears to have been various virtual explosions of species, very early on. Then, most of them died out, about 95%. It's a bit like human development in the womb. Neurons develop in hyper excess. Then, those that don't hook up to organs, muscles and whatnot, die off. Same w a lot of cells; those not needed die of, commit suicide, apoptosis. Example, we had webbed hands. The cells that make up the webbing commit suicide. It sculpts our hand to what we call normal. I wonder if there may be a correlation between embrionic development and development/evolution of the species. Are similar process/forces/principles at work in both events? Questions, questions.
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