Phase 2: Theme A - Demographic processes and cultural change: Project A002|
Lactose tolerance and population expansion in prehistoric Europe
SUPERVISOR: - Thomas, Shennan
Adam Powell (Research Department of Genetics, Evolution and Environment, University College London)
Mark Thomas (Research Department of Genetics, Evolution and Environment, University College London)
Stephen Shennan (Institute of Archaeology, University College London)
Gene-culture co-evolution and the spread of the lactase persistence trait.
This doctoral project will address archaeological evidence for the mode and timing of the spread of pastoralism and fresh milk drinking. The ability to digest the milk sugar lactose as an adult (lactase persistence) is a variable genetic trait in human populations. It is typically very common in Europeans and some African and Middle Eastern groups, whilst being rare elsewhere. In Europeans, genetic evidence suggests that the gene associated with lactase persistence has been the target of recent natural selection forces, possibly to a greater extent than anywhere else in the genome (Bersaglieri et al. 2004, Mulcare et al. 2004).
Archaeological analysis of the evidence for subsistence change across the Neolithic transition could, if coupled to quantitative models of gene-culture co-evolution, lead to a major reassessment of the relative roles of cereal agriculture and pastoralism in the peopling of Europe. If fresh milk drinking appeared as an early part of this process (as seems increasingly plausible; Balasse & Tresset 2002, Copley et al. 2003), then the initial distribution pattern of the lactase persistence gene may have produced very significant fitness differentials. Computer modeling has demonstrated that under certain demographic scenarios (high degree of endogamy, low population density) strong natural selection could drive the expansion of a population carrying the lactase persistence gene at the expense of surrounding populations. The project will involve archaeological assessment of the evidence for the location and timing of early dairying in Europe, as a control on such demographic models.
Balasse, M. & Tresset, A. (2002) Early weaning of Neolithic domestic cattle (Bercy, France) revealed by intra-tooth variation in nitrogen isotope ratios. J. Arch. Sci. 29: 853-859
Copley M, Berstan R, Dudd S, Docherty G, Mukherjee A, Straker V, Payne S, Evershed R (2003) Direct chemical evidence for widespread dairying in prehistoric Britain. PNAS 100: 1524-1529.
Bersaglieri T, Sabeti PC, Patterson N, Vanderploeg T, Schaffner SF, Drake JA, Rhodes M, Reich DE, Hirschhorn JN (2004) Genetic signatures of strong recent positive selection at the lactase gene. Am J Hum Genet 74:1111-1120.
Mulcare, CA., Weale, ME., Abigail L . Jones, Bruce Connell, David Zeitlin, Ayele Tarekegn, Dallas M. Swallow, Neil Bradman and Mark G. Thomas (2004) The T allele located 13.9 kb upstream of the lactase gene (LCT) (C-13.9kbT) does not predict or cause the lactase persistence phenotype in Africans. American Journal of Human Genetics 74: pp1102-1110.
FINAL PROJECT REPORT:
|•||Gerbault P., Liebert A., Itan Y., Powell A., Currat M., Burger J., Swallow D.M., Thomas M.G (2011).|
Evolution of lactase persistence: an example of human niche construction. Phil. Trans. R. Soc. B. Vol 366:863-77.
|•||Powell A., Thomas M.G., Shennan S.J (2009).|
Demography and variation in the accumulation of culturally inherited skills. In: M .J. O'Brien & S.J. Shennan (eds.) (ed\s) Innovation in Cultural Systems: Contributions from Evolutionary Anthropology. Cambridge, MA: MIT Press. 137-160.
|•||J. Burger, M. Kirchner, B. Bramanti, W. Haak, and M. G. Thomas (2007).|
Absence of the lactase-persistence-associated allele in early Neolithic Europeans. Proceedings of the National Academy of Sciences (USA). Vol 104:3736-3741.