3-billion-year-old genetic fossil traced

The collective genome of all life on Earth today went through a rapid growth spurt between 3.3 billion and 2.8 billion years ago, according to scientists who used computer algorithms to reconstruct the evolutionary history of thousands of genes.

The growth spurt coincides with the advent of a biochemical pathway known as electron transport that is “integral for photosynthesis as well as for respiration,” Lawrence David, a computational biologist at the Massachusetts Institute of Technology, told me.