when talking about evolution people seem to often dismiss animals "stuck in time"there are several animals who "did not evolve"a priapulus worms gene order have been perfectly still for 520 million years nowthis is estimated as their divergence time from arthropods, as the oldest worm fossils are a bit older than any arthropod fossil ever foundarthroposd have had massive re-structuring of their genetic order multiple times: 500 million years ago, 400 million years ago, 300 million years ago and maybe most dramatic changes were 120 million years agotoday priapulis can be barely linked to arthropods but it is. this worm is the cousin of the last common ancestor of arthropods and wormsmany other animals have "accelerated evolution" for example really shortly lived caenorhabditis worms (microscopic) seem to be evolving a lot for last 520 million years and are not even recognizable as an animal by their genes because they have gone too far from all other animals for developing fresh mutations every week for 520 million years>humans are another very stable branch but not comparable to priapulus worms because humans come from a stable, 30 million year old mammal branch and there have been unstable ancestors 120 million years ago but it does seem genetics were locked into stability mode back again, laterthis gene stability is something biologists never really talk about and have zero idea whence it came (I dont know it either)
>>17040449If the environmental pressure stays the same the creature will inevitably stay the same as well. Optimal designs don't change merely because time passes, the environment has to change for that to happen.
>>17040453but once arthropod change occured and they grew legs the first time, they have been accelerating in change ever since, their evolution is very fast compared to these ancient worms who still liveone of rare exceptions are horsheshoe crab who very well may be one of the first artrhopds and hasnt gone extinctit shows a slow rate of evolution and genes related to priapulid worms can be found from within horseshoe crabs but not really from insects in a meaningful way
>>17040449is that a penis
>>17040472Yes, there are tons of them in the ocean. You can suck as many as you like
>>17040449Good thread. It's not so much that biologists have no idea, there's a few hypotheses/mechanisms proposed, but they generally lack predictive power, probably because shit's so complex.
