Many [[Human evolution|human fossils]] have been found, but chimpanzee fossils were not described until 2005. Existing chimpanzee populations in West and Central Africa do not overlap with the major human fossil sites in East Africa. However, chimpanzee fossils have now been reported from [[Kenya]]. This would indicate that both humans and members of the ''Pan'' [[clade]] were present in the East African [[Rift Valley]] during the Middle [[Pleistocene]].<ref name=firstfossil>{{cite journal | title = First fossil chimpanzee | last = McBrearty | first = S. | coauthors = N. G. Jablonski | journal = [[Nature (journal)|Nature]] | date = 2005-09-01 | volume = 437 | pages = 105-108 | id = {{Entrez Pubmed|16136135}}}}</ref> | Many [[Human evolution|human fossils]] have been found, but chimpanzee fossils were not described until 2005. Existing chimpanzee populations in West and Central Africa do not overlap with the major human fossil sites in East Africa. However, chimpanzee fossils have now been reported from [[Kenya]]. This would indicate that both humans and members of the ''Pan'' [[clade]] were present in the East African [[Rift Valley]] during the Middle [[Pleistocene]].<ref name=firstfossil>{{cite journal | title = First fossil chimpanzee | last = McBrearty | first = S. | coauthors = N. G. Jablonski | journal = [[Nature (journal)|Nature]] | date = 2005-09-01 | volume = 437 | pages = 105-108 | id = {{Entrez Pubmed|16136135}}}}</ref> |