Did two of our ancestor species co-exist?

(Picture of a skull, believed to be 1.5 million years old, and part of a jawbone that’s nearly as old – by KAREL PRINSLOO / AP).

On 9 August 2007, a peer-reviewed research article was published in the scientific journal, Nature (“Implications of new early Homo fossils from Ileret, east of Lake Turkana, Kenya” by F. Spoor, M. G. Leakey, P. N. Gathogo, F. H. Brown, S. C. Antón, I. McDougall, C. Kiarie, F. K. Manthi & L. N. Leakey, Nature, 448, 688-691).