National Academy of Sciences | 150 Year Anniversary

Questions? Call 800-624-6242

| Items in cart [0]

The National Academies Press

HARDBACK
price:$54.95
add to cart

Rights & Permissions

topleft topright

Tempo and Mode in Evolution: Genetics and Paleontology 50 Years After Simpson (1995)
National Academy of Sciences (NAS)

Citation Manager

. "Molecular Genetics of Speculation and Human Origins." Tempo and Mode in Evolution: Genetics and Paleontology 50 Years After Simpson. Washington, DC: The National Academies Press, 1995.

Please select a format:

BibTeX EndNote RefMan


Page
202
bottomleft bottomright

The following HTML text is provided to enhance online readability. Many aspects of typography translate only awkwardly to HTML. Please use the page image as the authoritative form to ensure accuracy.


Figure 7 Three models of human evolution during the Pleistocene. The candelabra model proposes that the transition from H. erectus to H. sapiens occurred independently in different parts of the World. The African replacement model proposes that populations of H. erectus and archaic H. sapiens became extinct in Asia and Europe and were replaced by anatomically modern humans immigrating from Africa. The multiregional model proposes regional continuity and local selection pressures in different parts of the world, but with gene flow (indicated by the dashes connecting the vertical lines that represent different regional populations) due to occasional migrations between populations.

diverged from the lineage of African apes and humans about 13 Myr B.P.

H. erectus spread out of Africa shortly after its emergence from Homo habilis. Fossil remains of H. erectus are known from Indonesia (Java), China, and the Middle East, as well as Africa (Gibbons, 1994). H. erectus fossils from Java have been dated 1.81 ± 0.01 and 1.66 ± 0.04 Myr B.P. (Swisher et al., 1994). There are three models concerning the geographic origin of modern humans: candelabra, African replacement, and multiregional (Figure 7).

The candelabra model was proposed by Carleton S. Coon (1962), who argued that ''Homo erectus evolved into Homo sapiens not once but five times, as each subspecies, living in its own territory, passed a critical threshold from a more brutal to a more sapient state." Moreover, the threshold was crossed at different times, the Caucasoid race becoming sapiens first, whereas the Congoloids reached the sapiens condition some 200,000 years later. Coon's proposal was effectively criticized by several authors who pointed out the impossibility that the same species would

Page
202