The first of many

Half way down the west coast of Africa, in Gabon, the oldest examples of multicellular life has been discovered. The rocks date back 2.1 billion years. Looking at the growth patterns scientists deduced that these creatures exhibited cell-to-cell signalling and coordinated responses - a feature commonly associated with multicellular organization.

Two hundred million years earlier there had been a dramatic increase in the levels of oxygen in the atmosphere, a phenomenon that may well have contributed to this development.

http://www.nature.com/nature/journal/v466/n7302/full/nature09166.html