Important Building Blocks for Life Present on Earth 2.8 Billion Years Ago

One-Fourth of DNA Born by 2.8 Billion Years Ago

"About 27 percent of all gene families that exist today were born between 3.3 billion and 2.8 billion years ago, two researchers from MIT reported online Dec. 19 in Nature. The surge of gene births — which the scientists have dubbed the Archean expansion — predate some important changes in Earth’s early chemistry, including the appearance of large amounts of oxygen in the atmosphere....

"Genes for shuttling electrons burst onto the scene about 3.3 billion years ago, the researchers calculate. Those genes, known as electron-transport genes, are important for such processes as photosynthesis and respiration. By increasing the energy efficiency of some early life forms, these genes may have enabled populations to thrive.

"Genes for using oxygen appeared at the tail of the genetic expansion around 2.8 billion years ago, long before oxygen began accumulating in the atmosphere around 2.5 billion years ago. The team also found evidence for the birth of genes for processing nitrogen and for using iron, molybdenum, copper and other elements."

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