A quarter of all gene families existing today came into being between 3.3 billion and 2.8 billion years ago, two MIT scientists have reported in Nature. Related research may show how early organisms responded to and helped alter the planet’s chemistry. While the genetic predictions match geochemical data for many of the elements, a few appear to contradict ideas about Earth’s early history. For instance, the new data predict that genes for using nickel were increasing at a time when geochemists say nickel concentrations in the ocean were crashing. “Somebody’s wrong, and that’s what’s really exciting to me,” says geochemist Timothy Lyons.