Panspermia, Octopuses, and Comets 4/6

Interstellar bacteria and mass extinctions

Credit: David A. Aguilar / CfA —According to the panspermia hypothesis, around 4 billion years ago, on a young Earth with an atmosphere still devoid of oxygen, frequent impacts of asteroids and comets deposited tons of biological material of extraterrestrial origin in the oceans. As soon as the environmental conditions allowed it, organisms from space managed to survive and reproduce, transforming the Earth into a place teeming with life — a life that still flourishes, despite cataclysms of all kinds and periodic mass extinctions

Bacteria from space

Regarding the incredible replication power of bacteria, in their 1999 book “Astronomical origins of life,” Hoyle and Wickramasinghe wrote (page 101):

Start with a single living cell, say a bacterium. A typical doubling time by binary-fission for…