High-Profile Discovery

Searching for our origins—from "Lucy" to the earliest evidence of our own genus, Homo

►Fossil Record of the Earliest Human Evolution

IHO began its career focused on the early phases of human evolution (4 to 2 million years) with a field program at Hadar, Ethiopia, along with several other East African field localities. The novel long-term commitment to Hadar continues and has produced an unprecedented understanding of the biology and environment of the early biped Australopithecus afarensis. A recent expansion of this research is the paleolake drilling project to establish high-resolution ancient climate and environment information for early hominin lifeways, and several grants have been awarded/pending for this research.

Ongoing IHO fieldwork at Hadar and Woronso-Mille, Ethiopia, as well as other African sites at address the evolution and ecology of Australopithecus (3.0–3.4 million years ago) and the origin of Homo and stone-tool making (2.3 million years ago). 

Research Projects

Drimolen, South Africa

Years of painstaking excavation at the fossil-rich site of Drimolen, nestled within the Cradle of Humankind (a UNESCO World Heritage site located just 40 kilometers or around 25 miles northwest of Johannesburg in South Africa), has resulted in the recovery of several new and important fossils. The skull, attributed to Homo erectus, is securely dated to be two million years old.

Hadar, Ethiopia

Addresses the early evolution and ecological variation of Australopithecus (3.0–3.4 myr) and the origin of Homo and stone-tool making (2.3 myr). In 2007, this field project began to operate as ASU’s Hadar Field School, which has in three field seasons enrolled 46 undergraduates from ASU and other universities across the U.S. in a rigorous semester-abroad curriculum on field methods in human origins research.

Ledi-Geraru Research Project

Plio-Pleistocene hominin site in Ethiopia. Recovery of hominin fossils and preliminary identification of the time range of the deposits and evidence, and understanding the depositional environments and fossil distribution of the center of Paleolake, Hadar.


Only 30 miles north of Hadar, a research project at Woranso-Mille that began in 2005, led by IHO’s new director Yohannes Haile-Selassie, has yielded ample fossils from not only Lucy’s species, but at least two others—including one whose foot appears to be adapted to tree climbing. Some of these different species existed at the same time.

Major Funding

W.M. Keck Foundation ($1,200,000; ASU component = $497,168) “Disentangling the drivers of human evolution: Tectonics, climate, and habitat”. ASU PIs: Y. Haile-Selassie, C. Campisano, D. Feary, K. Reed, D. Su (Case Western Reserve U. as lead institution, 10 additional PIs)

National Science Foundation (BCS-ARCH) ($389,936; ASU component = $108,203) “Collaborative Research: Hominin diversity, paleobiology, and behavior at the terminal Pliocene from Ledi-Geraru (Afar, Ethiopia)”. PIs: R. Arrowsmith (lead), C. Campisano, K. Reed

National Science Foundation (BCS-Biological Anthropology) $311,206 Reconstructing the paleoecological context of major milestones in human evolution: Late Pliocene mammalian fossil assemblages from the Lower Awash Valley (Afar Region, Ethiopia), PI: Yohannes Haile-Selassie, Co-PIs: Kaye Reed, Denise Su.

National Science Foundation (BCS-Archaeology) $134,866. Collaborative Research: Hominin diversity, paleobiology, and behavior at the terminal Pliocene from Ledi Geraru (Afar, Ethiopia) PI: Ramon Arrowsmith, Co-PIs: Kaye Reed, Chris Campisano.

Notable Publications 

Mid-Pliocene hominin diversity: New insights from Woranso-Mille, Afar Region, Ethiopia. 2021. Haile-Selassie, Y.  In Y. Coppens and A. Vialet (Eds.), Un Bouquet D’Ancêtres. Proceedings of “Premières Humains: Qui Êtait Qui, Qui a Fait Quoi, Ou et Quand?” pp. 83–100. The Pontifical Academy of Sciences, Vatican, Italy.

Human burials at the Kisese II rockshelter, Tanzania. 2021. Laird, M.F., E.A. Sawchuk, A. Kwekason, A.Z.P. Mabulla, E. Ndiema, C.A. Tryon, J.E. Lewis, and K.L. Ranhorn. American Journal of Physical Anthropology.

Earliest known Oldowan artifacts at >2.58 Ma from Ledi Geraru, Ethiopia, highlight early technological diversity. 2019. Braun, D.R., Aldeias, V., Archer, W., Arrowsmith, J R., Baraki, N., Campisano, C.J., Deino, A.L., DiMaggio, E.N., Dupont-Nivet, G., Engda, B., Feary, D.A., Garello, D.I., Kerfelew, Z., McPherron, S.P., Patterson, D.B., Reeves, J.S., Thompson, J.C., Reed, K.E. Proceedings of the National Academy of Sciences 116, 11712-11717. https://doi.org/10.1073/pnas.1820177116

A 3.8-million-year-old hominin cranium from Woranso-Mille, Ethiopia. 2019. Haile-Selassie, Y., Melillo, S.M., Vazzana, A., Benazzi, S., and Ryan, T.M. ​​​​​​​Nature, 573, 214–219. https://doi.org/10.1038/s41586-019-1513-8.

Age and context of mid-Pliocene hominin cranium from Woranso-Mille, Ethiopia. 2019. ​​​​​​​Saylor, B.Z., Gibert, L., Deino, A., Alene, M., Levin, N.E., Melillo, S.M., Peaple, M.D., Feakins, S.J., Bourel, B., Barboni, D., Novello, A., Sylvestre, F., Mertzman, S.A., and Haile-Selassie, Y. ​​​​​​​ Nature, 573, 220–224. https://doi.org/10.1038/s41586-019-1514-7.

The evolutionary history of the human face. 2019. Lacruz, R.S., Stringer, C.B., Kimbel, W.H., Wood, B.A., Harvati, K., O’Higgins, P., Bromage, T.G., Arsuaga, J-L. ​​​​​​​ Nature Ecology and Evolution, 3: 726-736. https://doi.org/10.1038/s41559-019-0865-7

Related Links

Hadar Geoinformatics Project https://iho.asu.edu/research/HGP