The stellar baby boom period of the Milky Way sparked a flowering and crashing of life here on Earth, a new study suggests. Some 2.4 billion years ago when the Milky Way started upping its star production, cosmic rays—high-speed atomic particles—started pouring onto our planet, causing instability within the living. Populations of bacteria and algae repeatedly soared and crashed in the oceans. The researchers counted the amount of carbon-13 within sedimentary rocks, the most common rocks exposed on the Earth's surface. When algae and bacteria were growing in the oceans, they took in carbon-12, so the ocean had an abundance of carbon-13. Many sea creatures use carbon-13 to make their shells. If there is a lot of carbon-13 stored in rocks, it means life, the origin of which is still unknown, was booming. Therefore, variations in carbon-13 are a good indicator of the productivity of life on Earth.
see also: Complexity - The Great Dying