Luminescence characteristics and dose distributions for quartz and feldspar grains from Mumba rockshelter,Tanzania

Mumba rockshelter is a key archaeological site for the Middle and Later Stone Age occupation of East Africa, but its chronology has remained unresolved. We report the results of a dating study, focussing on the characterisation of the optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) properties of quartz- and potassium-rich feldspar grains. Quartz has previously proven troublesome for dating in East Africa. We identified five general types of quartz grain behaviour, based on the shapes of their OSL decay and dose–response curves. Dose recovery experiments and measurement of the natural samples revealed particular problems with quartz grains that had hyperbolic dose–response curves, low characteristic saturation doses and anomalously large changes in sensitivity between regenerative-dose cycles. The use of pulsed irradiation during measurement and standard and additional quality-assurance criteria during data analysis reduced the number of grains that suffered from these problems. We applied these procedures to individual grains of quartz from eight samples and, using appropriate statistical models, identified post-depositional mixing in three samples. The remaining samples had scattered equivalent-dose distributions typical of quartz grains that had received variable beta dose rates during burial. Stratigraphically consistent OSL ages were obtained for all but the deepest sample. Feldspar ages were estimated for the latter sample and three other samples, using the elevated temperature IRSL signal that exhibited low rates of anomalous fading. Fading-corrected feldspar ages for the latter three samples are consistent with their single-grain quartz ages, but single-grain dating is needed to address problems of post-depositional mixing.     

Ethnogenesis in Africa: Some models of unity and diversity

Asante, Molefi Kete, and Kariamu Welsh Asante, eds. African Cultures: the Rhythms of Unity. Westport, Connecticut: Greenwood Press, 1985/x + 270 pp. including references and index. $35.00 cloth.

Ismagilova, R. N. Ethnic Problems of the Tropical Africa: Can They Be Solved? Moscow: Progress Publishers, 1978. 302 pp. including references, selected bibliography, and index. $5.45 cloth.

Zwernemann, Jurgen. Culture History and African Anthropology. A Century of Research in Germany and Austria. Stockholm: Almqvist, 1983. 170 pp. including bibliography and index. SEK 95.00.     

New ways of organizing complex data: Multidimensional scaling

A. Kimball Romney, Roger N. Shepard and Sara Beth Nerlove, eds. Multidimensional Scaling: Theory and Applications in the Behavioral Sciences. New York: Seminar Press, 1972. Volume One: xvi + 261 pp. Figures and index. $12.95. Volume Two: xvi + 323 pp. Tables, figures and index. $14.75.     

RECENT POPULATION TRENDS IN THE USSR

Pending the publication of new Soviet population data based on the 1979 census, to be hald next January, the author reviews population trends in the 1970's. After a steady decline through much of the Soviet period, birth rates and death rates have stabilized for the country as a whole, although marked regional differences continue. An unexplained rise in infant mortality and an apparent reduction of life expectancy have led to the suppression of data in these areas. No ready explanation is found for a recent increase in female fertility and age-specific death rates. Abnormalities in the age-sex structure, resulting from past population catastrophes, continue to persist and indicate future labor shortages. Geographical differences in population growth rates, resulting from differential rates of natural increase and migration, are analyzed. Urbanization, a typical phenomenon of the Soviet period, continues apace, with the biggest increases in large cities despite a policy designed to discourage big-city growth. A crucial question is the optimal disposition of the growing labor pool in the Central Asian region-whether to foster local employment or encourage migration from Central Asia to labor deficit areas elsewhere in the Soviet Union.     

Still Bay and serrated points from Umhlatuzana Rock Shelter,Kwazulu-Natal,South Africa

Umhlatuzana Rock Shelter is a long-sequence Middle and Later Stone Age site in KwaZulu-Natal, South Africa. Jonathan Kaplan excavated the site and analysed the material in the 1980s as a rescue project. For many years thereafter the collection remained untouched, partly because of doubts raised about the stratigraphic integrity of the site. Using single-grain OSL dating we show that post-depositional mixing of sediment was restricted to time-specific, small-scale events. The OSL ages obtained for the Howiesons Poort and pre-Howiesons Poort are comparable to those of other southern African sites with unambiguous Howiesons Poort and Still Bay Industries. Based on morphological and other characteristics, we reason that the Still Bay is represented at Umhlatuzana, and announce the presence of a serrated point assemblage closely associated in time with the Still Bay points.     

The whistleblower and the canary: rhetorical constructions of climate change

This paper is concerned with the historical dimension of the current debates on climate change, and argues that the history of the understanding of climate change has itself become part of the rhetorical account. Key historic moments of disclosure and revelation have become central to the ways in which climate change is presented as a persuasive narrative today. This paper takes a discursive approach to exploring the background of these signal moments in climate change history, and aims to show how they have helped to shape the terms of the current debate.