Demic diffusion

Demic diffusion is a demographic term referring to a migratory model developed by Cavalli-Sforza, that consists of population diffusion into and across an area previously uninhabited by that group, possibly, but not necessarily, displacing, replacing, or intermixing with a pre-existing population (e.g. as has been suggested for the spread of agriculture across Neolithic Europe, and what occurred with the European colonization of the Americas).

In its original formulation, the demic diffusion model includes three phases, namely: (1) population growth, prompted by new available resources as in the case of early farmers, and/or other technological developments; (2) a dispersal into regions with lower population density; (3) a limited initial admixture^{[clarification needed]} with the people encountered in the process.

Evidence

Theoretical work by Luca Cavalli-Sforza showed that, if admixture between expanding farmers and previously resident groups of hunters and gatherers is not immediate, the process would result in the establishment of broad genetic gradients. Because broad gradients spanning much of Europe in the Southeast-Northwest direction were identified in empirical genetic studies by Cavalli-Sforza, Robert R. Sokal, Guido Barbujani, Lounès Chikhi and others, it seemed likely that the spread of agriculture into Europe occurred by the expansion and spread of agriculturists, possibly originating in the Fertile crescent of the Near East region. This is referred to as the Neolithic demic diffusion model.

Craniometric^[1][2] and archaeological^{[3][4][5][6][7]} studies have also arrived at the same conclusion.

References

1. Chicki, L; Nichols, RA; Barbujani, G; Beaumont, MA. 2002. Y genetic data support the Neolithic demic diffusion model. Proc. Nat. Acad. Sci. 99(17): 11008-11013.

1. ^ C. Loring Brace, Noriko Seguchi, Conrad B. Quintyn, Sherry C. Fox, A. Russell Nelson, Sotiris K. Manolis, and Pan Qifeng, "The questionable contribution of the Neolithic and the Bronze Age to European craniofacial form," in Proceedings of the National Academy of Sciences of the USA (Jan. 3, 2006). Vol. 103, No. 1, pp. 242-247. [1] doi: 10.1073/pnas.0509801102
2. ^ F. X. Ricaut, M. Waelkens, "Cranial Discrete Traits in a Byzantine Population and Eastern Mediterranean Population Movements," in Human Biology, Wayne State University Press (Aug. 2008). Vol. 80, Issue 5, pp. 535-564. [2] doi: 10.3378/1534-6617-80.5.535
3. ^ M. Zvelebil, in Hunters in Transition: Mesolithic Societies and the Transition to Farming, M. Zvelebil (editor), Cambridge University Press: Cambridge, UK (1986) pp. 5-15, 167–188.
4. ^ P. Bellwood, First Farmers: The Origins of Agricultural Societies, Blackwell: Malden, MA (2005).
5. ^ M. Dokládal, J. Brožek, Curr. Anthropol. 2 (1961) pp. 455–477.
6. ^ O. Bar-Yosef, Evol. Anthropol. 6 (1998) pp. 159–177.
7. ^ M. Zvelebil, Antiquity 63 (1989) pp. 379–383.

External links

• Estimating the Impact of Prehistoric Admixture on the Genome of Europeans, Dupanloup et al., 2004
• Origin, Diffusion, and Differentiation of Y-Chromosome Haplogroups E and J: Inferences on the Neolithization of Europe and Later Migratory Events in the Mediterranean Area, 2004
• Y genetic data support the Neolithic demic diffusion model, Chikhi 2002.
• Paleolithic and Neolithic lineages in the European mitochondrial gene pool, Cavalli-Sforza 1997.
• Clines of nuclear DNA markers suggest a largely Neolithic ancestry of the European gene, Chikhi 1997.

See also

Cultural diffusion: the spread of culture via interaction between individuals from one culture to another or within a culture