Durham E-Theses Down to the river: marital movement and genetic structure on the Hispanic Portuguese border Eizaguirre, Maria How to cite: Eizaguirre, Maria (1994) Down to the river: marital movement and genetic structure on the Hispanic Portuguese border, Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/5821/ Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in Durham E-Theses • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full Durham E-Theses policy for further details. Academic Support Oce, Durham University, University Oce, Old Elvet, Durham DH1 3HP e-mail: [email protected] Tel: +44 0191 334 6107 http://etheses.dur.ac.uk 2 The copyright of this thesis rests with the author. No quotation from it should be published without his prior written consent and information derived from it should be acknowledged. 'own to iver: Marital Movement And Genetic Structure On The Hispanic-Portuguese Border Thesis Submitted For The Degree Of Master Of Science (M.Sc.) Department of Anthropology University of Durham Maria Eizaguirre September 1994 Para mi abuelo Paco. Este trabajo aunque humilde y ingles, se lo debo a tus genes. ABSTRACT The aim of this study was to provide preliminary evidence on the impact of the River Minho on the genetic structure of the Hispanic-Portuguese populations that occupy its valley. The study was aimed to be descriptive rather than analytical, so ethnographic material was used as background information to predict the constraints imposed by the river's dual role as a political and geographic barrier. These constraints were then examined in an analysis of marital mobility and genetic structure in the valley in an investigation which involved two stages. Firstly, information derived from dispensations and isonymy was used to understand the degree of inbreeding of the populations and underlying genetic structure. Secondly, marital migration data was used to describe the admixture of the populations in terms of extent, direction and orientation of marital movement, to provide evidence on the barriers imposed by the River Minho. Ethnographic material was used in the interpretation of results. Results obtained point to patrilocal agricultural communities with high inbreeding, low admixture rates, high endogamy and local mate exchange where short range movement predominates. These characteristics are present in both sides of the river, regardless of national affiliation or of the presence in the Portuguese area of a growing urban centre. Preliminary findings suggest that the River Minho may well be acting as a geographic rather than a political boundary to gene flow and genetic differentiation. Table of Contents Page Acknowledgements i List of Tables ii List of Figures iv Declaration v Copyright vi Chapiter 1 INTRODUCTION 1 Chapter 2 DATA COLLECTION 4 2.1 The Data Sources 4 2.2 Marriage Registers As A Data Source 5 2.3 Handling The Data 8 2.4 Contents Of The Study 10 Chapter 3 THE GEOGRAPHY AND SQCIO-CULTURAL ASPECTS OF THE MINHQ RIVER VALLEY 11 3.1 The Geography 12 3.2 Socio-Cultural Aspects 16 3.3 Summary 25 Chapter 4 INBREEDING AND ISOLATION 27 4.1 Consanguinity Analysis 29 4.2 Isonymy Analysis 46 4.3 Comparing Ft And a 59 4.4 Conclusions 62 Appendix 1: Isonymy Plots 63 Chapter 5 DISTANCE AND ORIENTATION 70 5.1 Marital Distance 70 5.2 Orientation Of Movement 90 5.3 The River Minho: A Geographic or a Political Boundary? 105 Appendix 2: Frequency Distributions (Distances Travelled) 108 Chapter 6 DISCUSSIONS AND CONCLUSIONS 113 BIBLIOGRAPHY 124 AC_I^NQW1UEPGMJEN.T§ I feel indebted to the following people for the help provided during the year for the realisation of this thesis; - Dr. Malcolm Smith, for being an excellent supervisor and friend and a constant source of encouragement and support. - The Parkes Foundation, whose Grant for Research in Biological Anthropology covered the expenses of my fieldwork in Galicia and Portugal. - Dr. Anthony Boyce, from Oxford University, who kindly allowed me to use his personal computer in the field and back in Durham. - Dr. Vicente Fuster, from the Universidad Complutense de Madrid, for his advice and suggestions. - Dn. Ernesto Iglesias, from the Archivo Diocesano in Tuy, for his help during my fieldwork. He provided the books, advice and some unpublished material. - The Arquivo Distrital at Viana do Castelo. Muito obrigada. -The Computer Centre at Durham University, and especially Ms. Cathy Thompson, Mr. Barry Cornelius, Dr. Barbara Smith and Mr. Bob Sheehan. The help with SPSS, Emacs and DOS was both needed and appreciated. -The help from the Department of Anthropology at Durham University in the past four years. -Magaly Costas Costas for her help with the subject and her company during the months of fieldwork. -Alison Todd, for her help and criticisms of this dissertation and during the year. -My parents, Ana and James Trask, for enduring my absences in Durham and abroad and being supportive at all times. They are the reason to be. List of Tables Page Table 4.1 Total Marriages (T.M), Consanguineous Marriages (CM) and Degrees of Relationship Including Fourth Degree and Multiple Consanguinity (M.M) 34 Table 4.2 Absolute and Relative Frequencies of the Different Types of Consanguineous Matings in Ten-Year Cohorts: Galicia 35 Table 4.3 Absolute and Relative Frequencies of the Different Types of Consanguineous Matings in Ten-Year Cohorts: Portugal 35 Table 4.4 Total Marriages (T.M), Consanguineous Marriages (CM) and Degrees of Relationship up to the Third Degree 36 Table 4.5 Contribution of First and Second Cousin Marriage to Consanguinii Frequency (%) for Galicia and Portugal with (a) and without (b) Melgaco 37 Table 4.6 Total Number of Marriages (T.M), Consanguineous Marriages (CM), Consanguinity Frequency (%) and Mean Inbreeding Coefficients (a) 38 Table 4.7 Consanguinity and Pre-Marital Migration: Proportion of Consanguineous Marriages Involving Pre-Marital Movement (PMM), Range in Kilometres and Contribution to the Percentage c the Different Degrees of Relationship 40 Table 4.8 Fr Values for Each Type of Isonymy and for the Mean Isonymy Value (mean Fr) 55 Table 4.9 Fn Values for Each Type of Isonymy and for the Mean Isonymy Value (mean Fn) 56 Table 4.10 Ft Values for the Two Areas, With and Without Melgaco 57 Table 4.11 Comparison of Inbreeding Coefficients Derived from Dispensatior up to the Fourth Degree (a) and from Isonymy (Ft) 59 Table 5.1 Endogamy, Spatial Exogamy and Admixture Rate: Galicia 73 Table 5.2 Endogamy, Spatial Exogamy and Admixture Rate: Portugal 74 Table 5.3 Average (Mean) and Median BP and RP Distances Travelled: Galicia 76 ii Page Table 5.4 Average (Mean) and Median BP and RP Distances Travelled: Portugal 78 Table 5.5 Proportion of Exogamous Partners from the concello and the Archbishopric for Galician parishes 93 iii List of Figures Page Figure 1.1 Factors Which Affect the Genetic Structure of Populations 2 Figure 3.1 Map of the Area 13 Figure 4.1 Surname Transmission in the LASS system 49 Figure 4.2 Plotting Isonymy Values to Understand Residence Patterns 50 Figure 4.3 Patrilocality in the Minho River Valley 53 Figure 5.1 a) Proportion of Exogamous Males and Females: Galicia 81 b) Proportion of Exogamous Males and Females: Portugal 83 Figure 5.2 Distances Travelled Into the Region 88 a) Movement Into Galicia 88 b) Movement Into Portugal 88 Figure 5.3 The Minho River as a Political Border Between Galicia and Portugal 92 Figure 5.4 Orientation of Movement: Galicia 97 Figure 5.5 Orientation of Movement: Portugal 101 Figure 5.6 Female Orientation of Movement: Galicia 102 Figure 5.7 Male Orientation of Movement: Galicia 102 Figure 5.8 Female Orientation of Movement: Portugal 103 Figure 5.9 Male Orientation of Movement: Portugal 103 Figure 5.10 Exchange Across the Minho 105 iv Declaration I declare that material submitted for this M.Sc. thesis has not been submitted for a degree in this or any other university. Copyright © The copyright of this thesis rests with the author. No quotation from it should be published without her prior consent and information derived from it should be acknowledged. vi CJtontecJl INTRODUCTION The study of the genetic structure of a population encompasses the two main branches of anthropology, for it has very clearly defined social and biological aspects; the name biodemography (Abade, 1992) is attached to it to take account of this interdisciplinary nature. The term attempts to take into consideration the methodology characteristic of Historical Demography fitted into a framework provided by Population Genetics (Swedlund, 1980) to answer questions like: how did the genetic structure establish itself in the population? what evolutionary mechanisms will modify such a structure? with what genetic results? (Cavalli-Sforza and Bodmer, 1971). In the present study, the populations of the River Minho Valley in the border area between Spain and Portugal are studied to provide answers to the questions above. The river itself has had a prominent role in the development of the genetic structures of the populations that form its valley, and that includes not only the establishment of such structures but also their modification through time. It is important that time has seen the evolution of the river itself, from a purely geographic phenomenon to a political division separating the two countries after the birth of Portugal from Spain in the twelfth century A.D.