This graph shows a possible evolution of the genus homo, adapted from notes by Bernard Wood and Jennifer Baker, both of the Department of Anthropology at George Washington University. To the left is the scale, going from zero to eight million years ago. In bold are the taxa that are conventionally included in the genus. This data (from first appearance to last appearance) is based on fossils, but the span of existence may have been longer.
As new clues about the disappearance of Neanderthals appear, read more about the Evolution in the Genus Homo in the 2011 Annual Review of Ecology, Evolution, and Systematics.