Darwin sought to not only produce a new scientific truth, but also to put an end to polygenism, the current scientific discourse on human origins that gave tacit and at times explicit support for slavery: ‘... when the principle of evolution is generally accepted, as it surely will be before long, the dispute between the monogenists and polygenists will die a silent and unobserved death.’ (Charles Darwin, Descent of Man, p. 235)

Saturday, March 10, 2012

Climate and Migration in Africa, c.1000 BCE

An interesting article in Science on migrations in Africa coinciding with the savannas replacing rainforest in central Africa, c.1000 BCE.

Germain Bayon*, Bernard Dennielou, Joël Etoubleau, Emmanuel Ponzevera, Samuel Toucanne, Sylvain Bermell.  Institut Français de Recherche pour l’Exploitation de la Mer (IFREMER), Unité de Recherche Géosciences Marines, F-29280 Plouzané, France.


About 3000 years ago, a major vegetation change occurred in Central Africa, when rainforest trees were abruptly replaced by savannas. Up to this point, the consensus of the scientific community has been that the forest disturbance was caused by climate change. We show here that chemical weathering in Central Africa, reconstructed from geochemical analyses of a marine sediment core, intensified abruptly at the same period, departing substantially from the long-term weathering fluctuations related to the Late Quaternary climate. Evidence that this weathering event was also contemporaneous with the migration of Bantu-speaking farmers across Central Africa suggests that human land-use intensification at that time had already made a major impact on the rainforest.

Published Online February 9 2012
Science 9 March 2012:
Vol. 335 no. 6073 pp. 1219-1222
DOI: 10.1126/science.1215400