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by simonh 1467 days ago
It’s relatively easy once you have evolved the biochemical infrastructure to support it, but on Earth that took several billions of years to achieve. There’s no way around it, no amount of hand waving how easy it is negates the fact it took billion years of evolution to do it.

Also most of those forms of multicellularity are extremely basic, little more than tangles or sheets of cells, even after hundreds of millions of years of further evolution. That’s not likely to get to intelligent life.
2 comments
gus_massa 1466 days ago
I think we agree. One you have prokaryote it's probably easy to get multi cellular prokaryotes.

My guess is that the transition form eukaryotes to prokaryotes in the hard step.

Also, photosynthesis seams to be more complicated than what I expected. Perhaps that is the hardest step. (It's an indirect step to intelligent life, but perhaps a lot of free oxygen to burn food efficiently is necessary for intelligent life.)

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sterlind 1467 days ago
it took at most a billion years. there may have been predecessors that were lost - the only evidence we have from that era is what made it into the DNA of surviving ancestors.

I guess I still feel like abiogenesis should be the bigger filter. we have ideas and suggestive experiments about how it happened, but nothing's come close to convincingly demonstrating how fully self-replicating life can evolve through simple steps. whereas endosymbiosis just seems to require two prokaryotes from different trees surviving in the same membrane, and it's not difficult for me to imagine a plasmid slipping in and making copies of enough enzymes to get by.

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simonh 1466 days ago
As I pointed out though, endosymbiosis isn’t by itself enough. It can provide many benefits, one of which might be the ability to develop complex sophisticated multicellular organisms, but it doesn’t guarantee that capability.

This sub thread is specifically about developing intelligent life, and of all the branches of multicellular life on earth only one has achieved that capacity, animals. None of the others seem to be anywhere close, or ever likely to be, for all their fancy biochemical tricks. So it seems like the vast majority of endosymbiotic events really don’t help much towards that outcome.

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