Public Lecture : Em Prof N van der Merwe, Nov 2012

Nov 05, 2012 No Comments by

Nikolaas J. van der Merwe FRSSAf , Professor Emeritus of Natural History, Dept of Archaeology, University of Cape Town will present a public lecture entitled   “West and East African monsoons in Africa: isotopic evidence for their effect on early animals”
Wednesday 14th November 2012 at 5 pm at the SAAO Auditorium, Observatory Road, Observatory

Many will be familiar with East African and Asian monsoon rainfall systems; fewer with the fact that there is also an Atlantic system. The contrasting diets of two early hominin species that were present in Tanzania at ca. 1.8 Ma (million years ago) – Homo habilis and Paranthropus boisei (Zinjanthropus) – have been determined by means of stable carbon isotope analysis of their tooth enamel.  The diet of two specimens of P. boisei from Olduvai and Peninj proved to be particularly unusual, with 80% of its carbon derived from C4 plants.  It is suggested that the diet consisted primarily of plants. This observation has been supported in an analysis by other investigators of 22 specimens of P. boisei from Kenya. The goal of the current presentation is to describe the isotopic ecology and diets of fossil fauna that were present at the same time as the fossil hominins.  The tooth enamel of 145 faunal specimens from Olduvai Gorge, Middle Bed I (ca. 1.785 – 1.83 Ma) and the Lowermost Bed II (ca. 1.75 – 1.78 Ma) were assessed by means of stable carbon and oxygen isotope (d13C and d18O) analysis. The results from the fossil fauna were compared with those of 77 modern specimens (120 measurements) from nature reserves in Tanzania, primarily from the Serengeti National Park that adjoins Olduvai. The carbon isotope ratios for both fossil and modern specimens show that the habitats in which these faunal populations lived were quite similar, i.e., a grassland or wooded grassland. They had enough bushes and trees to support a few species of browsers, but most of the animals were grazers or mixed feeders. The oxygen isotope ratios of the fossil and modern animals were very different, however, suggesting strongly that the primary source of moisture for the rain in the Olduvai region has changed during the past 1.75 million years, apparently from the Atlantic to the Indian Ocean.

About the Speaker : go to N van der Merwe


*Directions to SAAO Auditorium : Coming from the N2,turn off to the M57 – Liesbeek Parkway; turning in the direction of Cape Town and continue to the traffic lights with Hartleyvale (hockey and football) on your left. Turn right at traffic lights into Observatory Road, pass the River Club; the S A Astronomical Observatory is next on the left. Once through the security gates bear left following the SALT signs to the last building on the left (white with stoep & ramp).

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