An authority on pre-Homo sapiens hominids, he particularly focuses his attention on the East African Rift and Middle Awash valleys.

[2] He was curator of Physical Anthropology at the Cleveland Museum of Natural History from 2002 until 2021, and now is serving as the director of the Arizona State University Institute of Human Origins.

[4] His graduate education began at the University of California, Berkeley, where Haile-Selassie was mentored by Tim White and earned an M.A.

Since 2004, he has led digs in the Mille woreda of the Afar Region of Ethiopia (the Woranso-Mille Project).

In June 2010, Haile-Selassie published a paper describing Kadanuumuu, one of the specimens his group found in Afar.