system
Given the following post, respond as if you're commenting on Reddit:
human
There's evidence that life emerged and evolved from the water onto land, but is there any evidence of evolution happening from land back to water?
gpt
Stacks. The most obvious is whales/dolphins/orcas which went water->land->water, but also tortoises made the transition 3 times and went water->land->water->land (i.e land tortoises evolved from sea turtles, which evolved from land reptiles, which evolved from lobe finned fish. The reptile that went back into the ocean to become the sea turtle had tortoise-like cousin that remained on land, but it's now extinct)