The synthesis of simple organic molecules such as formaldehyde (H₂CO), methanol (CH₃OH), and simple hydrocarbons in the dense molecular clouds of the interstellar medium occured once sufficient carbon was present. This process has been ongoing for billions of years but became more prevalent as the universe aged and more carbon became available.

Big History Thresholds: 1=Big Bang | 2=Stars&Galaxies | 3=Chemicals | 4=Solar System | 5=First Life | 6=TI | 7=Agrarian | 8=Science

New Chemical Elements: With threshold 3, the Periodic Table expands. While Big History dates this to the expansion of elements about 13.5 billion years ago, I’m showing it in my timelines a bit later at 10 BYA, when those heavier elements started forming molecules. This helps bridge the gap from elements to life.