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owiseone23 t1_jac0yw0 wrote

it's not uncommon for traits to evolve across "fitness valleys". That is, a trait with positive fitness that requires multiple generations to evolve with intermediate generations having negative fitness.

With a large population and a lot of time, random variation makes it possible to evolve across fitness valleys.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2711507/

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