science-junkie: Oxygen fluctuations stalled life on Earth One of the biggest riddles in Earth’s history is why animals did not evolve after a spike in oxygen levels approximately 2.3 billion years ago. Instead, despite what scientists had thought was

science-junkie: Oxygen fluctuations stalled life on Earth One of the biggest riddles in Earth’s history is why animals did not evolve after a spike in oxygen levels approximately 2.3 billion years ago. Instead, despite what scientists had thought was

tags: Phil's ramblings, fun,

from: https://passionategeek.tumblr.com/post/91768489580