One thing worth mentioning is that proto-eukaryotic cells originally got the energy to focus on larger scale things by capturing other prokaryotic cells. Mitochondria and chloroplasts look a lot like simplified bacteria that specialise in producing ATP and glucose+oxygen, respectively, both of which give the cell more energy. They even have their own, specific DNA inside them.
To get really speculative, this is quite similar to how agriculture and the resulting centralisation+specialisation allowed for the explosion of civilization, where the last ~10k years have overwhelmingly more complex stuff than the preceding 100k years.
One thing worth mentioning is that proto-eukaryotic cells originally got the energy to focus on larger scale things by capturing other prokaryotic cells. Mitochondria and chloroplasts look a lot like simplified bacteria that specialise in producing ATP and glucose+oxygen, respectively, both of which give the cell more energy. They even have their own, specific DNA inside them.
To get really speculative, this is quite similar to how agriculture and the resulting centralisation+specialisation allowed for the explosion of civilization, where the last ~10k years have overwhelmingly more complex stuff than the preceding 100k years.