stasis

Horseshoe crabs are survivors by anyone’s measure; they have carried on their lives virtually unchanged, according to the standard evolutionary timeline, for 450 million years. This not only points to incredible stasis against alleged forces of evolution; it also means they have survived at least three global extinctions that evolutionary biologists and geologists say wiped out most other species. Not only that, the world has changed drastically since they allegedly evolved from who-knows-what arthropod ancestors – perhaps trilobites, that appeared in the Cambrian Explosion without ancestors. But the numerous, successful trilobites did not survive the global extinctions. Given these contradictory facts, how can the horseshoe crab possibly be an exhibit for evolution? A recent article shows how.