Accelerated, uplift-driven incision leading to increased sediments removal from the Ethiopian Plateau Paleo-climatological and paleo-anthropological circumstantial “evidence” (Making the case against increased

precipitation)

From Hominoids to Hominins

• Between 7 and 4 Ma there was a lineage split between Hominoids and Hominins with bipedalism (walking upright on two legs) been taken as the defining Hominins characteristic

• Hominoid fossils are widely found in Africa and Eurasia. However, all of the early (older than 3 Ma) Hominoid fossils are located along the East African Rift

Lady Lucy (3.2 Ma) also known as Dinkenesh (Beautiful in Amharic) was discovered in Afar in 1974 by Maurice Taieb (Tunisian – French) and Donald Johanson (American) of the International Afar Research Expedition (IARE)

Kikika Baby (3.3 Ma) was discovered in Afar (~10 km away from Lucy cite) in 2002 by Zeresenay Alemseged (Ethiopian) of the Max-Planck Institute for Evolutionary Anthropology

Alemseged et al (2006) – Nature

Ardi (4.4 Ma old hominin and 1.2 meters tall) was discovered in the Afar Depression in Ethiopia and her evolution and habitat are summarized in 11 articles in Science last month.

PBS – Nova will broadcast a 3-episodes series entitled “Becoming Human” Today November 3, November 10, and November 17.

Hanson (2009) – Science

The Savanna Hypothesis • Darwin (1871) summarized that “Human evolution

was a consequence of adaptive change on the African savanna”.

• A global-scale change from C3 photosynthesizing (wood-dominated) vegetation to C4 (grass-dominated) vegetation in the late Miocene (8–6 Ma) has been suggested by stable carbon isotope analysis of fossil tooth enamel (Cerling et al., 1997 – Nature).

• Compilation of paleo-climatic data by Cane and Molnar (2003 - Nature) suggests that this woodland to grassland transition, indicative of increasing aridification, took place ca. 3–4 Ma in East Africa.

Biosphere Shift and Uplift • Pickford (1990 – J Human

Evolution) argued for a strong connection between East Africa aridification and the Neogene uplift of the Roof (Wall) of Africa along the 6000 km long East African Rift System

• Atmospheric and biospheric simulation by Sepulchre et al. (2006 - Science) concluded that uplift of East African topography had a first-order impact on aridification by inhibiting a zonal circulation of moist air

Sepulchre et al. (2006 – Nature)

Sepulchre et al. (2006 – Science)

Concluding Remarks

NSF should give Missouri S&T more money to conduct more scientific research in the Nile System