STEFANO FIORINI GIUSEPPE TAGARELLI ALESSIO BOATTINI DONATA LUISELLI ANNA PIRO ANTONIO TAGARELLI DAVIDE PETTENER Ethnicity and Evolution of the Biodemographic Structure of Arb ¨ ereshe and Italian Populations of the Pollino Area, Southern Italy (1820–1984) ABSTRACT In the present study, we show how, through time, an ethnic mosaic and a changing social and economic context translated into intrapopulation differentiation and a change in genetic barriers between populations. Surname analysis was applied to a sample drawn from two centuries of marriage records in ten Arb¨ ereshe and nine Italian villages of southern Italy to evaluate the evolution of internal differentiation and changes in genetic relationships between populations. Marital isonymy and subdivision into subpopulations was higher in the Arb ¨ ereshe. Genetic barriers coinciding with ethnic boundaries characterized the 1800s. In the second half of the 1900s, ethnic differentiation disappeared. We hypothesize that socioeconomic changes, such as increased outmigration and regional mobility, were the forces that progressively eliminated the ethnic-related genetic differentiation in the region. This study has important implications for an understanding of the relationship between genetic evolution and the cultural milieu involving enforcement of ethnic differences. [Keywords: biocultural evolution, ethnicity, biodemography genetic boundaries, Arb¨ ereshe] T HE GENETIC EVOLUTION of human populations is influenced by evolving cultural and socioeconomic contexts and by the geographic and ecological characteris- tics of the environment. In this study, we aim to show how, through time, an ethnic mosaic and changing social and economic milieus affected intrapopulation differentiation and genetic barriers between Arb¨ ereshe (Italo-Albanian) and Italian communities living in the same geographic area. 1 The influence of geographic isolation on the genetic evolution of human populations has been widely explored using biodemographic methodologies. Surnames are equiv- alent to markers associated with the Y-chromosome with ex- tremely high allele-like variability. Therefore, surname anal- ysis is a particularly useful tool in this line of investigation. Mountain populations of Mediterranean Europe have been investigated using surname analysis: for example, in the Pyrenees (Gonz´ alez-Mart´ ın and Toja 2002), in central Spain (Blanco Villegas et al. 2004; Fuster et al. 1996), in the AMERICAN ANTHROPOLOGIST, Vol. 109, Issue 4, pp. 735–746, ISSN 0002-7294 online ISSN 1548-1433. C  2007 by the American Anthropological Association. All rights reserved. Please direct all requests for permission to photocopy or reproduce article content through the University of California Press’s Rights and Permissions website, http://www.ucpressjournals.com/reprintInfo.asp. DOI: 10.1525/AA.2007.109.4.735. Apennines (Danubio et al. 1995; Pettener 1985, 1990), and in the Italian Alps (Martuzzi-Veronesi et al. 1996; Pettener et al. 1994). The results of these investigations are partic- ularly representative because of the reduced biases of sur- name analysis in isolated contexts, in which surnames have a low polyphyletic origin and the populations have low im- migration rates. Genetic studies are increasingly recognizing the impor- tant effects of socioeconomic, historical, and cultural fac- tors on the genetic evolution of human populations. For example, the effects of religion, historical migration pat- terns, and unique historical events or crises have been doc- umented (Bittles and Smith 1994; Crawford et al. 1995; Relethford and Crawford 1998; Smith and Bittles 2002), al- though agreement on which of these elements leaves the most important mark has not been reached (see, e.g., Martin et al. 2000; North et al. 2000). Part of this difficulty is related to the complex interrelation of these factors (Smith and