In 1992, his group discovered the earliest Acheulean in which the results were the cover feature in Nature.[4] He credits this major discovery in part to the EPRDF bringing stability to Ethiopia thus allowing the research group to work in remote areas.[3] The next major discovery was in 1997, when his group discovered Australopithecus garhi. The fossilized remains of Homo sapiens idaltu were discovered at Herto Bouri near the Middle Awash.[5][6] Over the years his excavations continued to find Australopithecus anamensis[7] and Homo erectus as well as discovering five new species making Ethiopia the richest site of early human ancestry.