Steroids discovered in 1.6 billion-year-old rock may help scientists solve a long-standing mystery about the evolution of single-celled life.
These compounds are produced by eukaryotic organisms, which are defined by having cells with nuclei and interior organelles bound by membranes. Modern eukaryotes include plants, fungi and animals. In contrast, prokaryotes — bacteria and archaea — lack these features. Based on molecular data, researchers know that single-celled eukaryotes first evolved at least 2 billion years ago, but there is very little fossil record of their earliest days.
