A Demographic Study of Crosthwaite Parish: Some Genetic Implications
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Durham E-Theses A demographic study of Crosthwaite parish: some genetic implications Challands, Hazel How to cite: Challands, Hazel (1978) A demographic study of Crosthwaite parish: some genetic implications, Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/8260/ 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 ABSTRACT This thesis studies the demographic history of Crosthwaite Parish, Cumberland (Cumbria) during the period 1560-1800, and attempts to assess the factors affecting population change in the region over that period. It uses the demographic material to assess the influence of some of the population changes on the genetic structure of the population. The study starts with a general introduction to the geography and population history of the region. The second chapter describes the methods used to record and cross-reference the Anglican parish registers which were the main source of material for this research. This is followed by an outline of the types of analysis used to obtain demographic information, and by a description of some attempts to assess pre-census population sizes in England and Wales. The main section of the work involves the use of 'cohorts' to study changes in the size of the breeding population, family size, age at marriage, migration rates and the sex ratio of migrants. Indices of genetic isolation are calculated to indicate the likelihood of genetic drift occurring at any point during the period studied. A study of isonymy is used to calculate inbreeding coefficients. The conclusion discusses the results obtained, and assesses the limitations and potential of historical population studies. A Demographic Study of Crosthwaite Parish some Genetic Implications by Hazel Challands A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY 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. Department of Anthropology University of Durham i CONTENTS page number List of tables iii List of figures v Acknowledgements vi Introduction vii Notes on some historical population studies x CHAPTER 1 Geographical and historical background ... 1 Geology ... ... ... ... ... ... ... ... 1 CHiHcitc ••• • • • • • • • • • 2 Vegetation ... ... ... ... ... ... ... 3 Geography of Crosthwaite Parish 5 Communications ... ... ... ... ... ... ... 8 General background history 9 CHAPTER 2 Materials and methods 20 The contents of the Crosthwaite registers 20 (i) Baptisms 20 (ii) Marriages 24 (iii) Burials 24 Method of analysis of the Crosthwaite registers ... 25 Pre-census population size estimates 30 CHAPTER 3 An outline of the population change in Crosthwaite parish 1560-1970 34 1562—1800 ... ... ... ... ... ... ... ... 34 1801 onwards ... ... ... ... ... ... ... 43 CHAPTER 4 Breeding population and effective breeding population 49 The calculation of the breeding population 49 Factors affecting changes in cohort sizes 54 Effective breeding cohorts 66 ii page number (i) Inbreeding 67 (ii) Variation in family size 67 (iii) Sex ratio 69 Effective breeding population sizes and genetic drift ... 70 Index of isolation 71 CHAPTER 5 Migration 76 (a) Migration rates 76 (i) Parish exogamy 77 (ii) Dummy marriages 84 (iii) Name data: 86 from marriage records 87 from baptism records 89 (b) Immigrant sex ratio 91 (c) Marriage distance and orientation ... 97 (i) Marriage distance 97 (ii) Orientation of movement 102 CHAPTER 6 Isonymy 108 114 CHAPTER 7 Conclusion Appendix - A brief history of parish registers. Deficiencies in the registration system 118 Registration deficiencies 119 Bibliography 122 iii LIST OF TABLES page number 3.1 Population of Keswick urban district (UD), Cumberland administrative county (AC), and county borough (CB), and England and Wales 46 4.1 Breeding cohort sizes 52 4.2 Mean age at first marriage of women 57 4.3 Mean family size 57 4.4 Proportion of childless marriages 61 4.5 Effective breeding cohort size (Ne) adjusted for inbreeding (F) 68 4.6 Effective breeding cohort size (Ne) adjusted for 2 variance in family size (k ) - all families 68 4.7 Index of isolation (Nem) based on dummy marriages ... 73 4.8 Index of isolation (Nem) based on the proportion of new names ... ... ... ... ... ... ... 73 5.1 Marital movement - proportions of parish-exogamous IQSUTIT icl^GS a a • a • a a a a ••• • a a a a • 79 5.2 Parish exogamy. Shropshire parishes combined ... 80 Durham parishes ... ... ... ... ... ... 81 Northumberland parishes 82 Deerfield, Massachusetts 82 5.3 Post-marital movement. Immigration rates: ratio of dummy marriages and fertile parish exogamous marriages to the breeding population 85 5.4 Marital movement. Immigration rates: ratio of new names to the total number of names, and net loss/gain of names, based on marriage records 88 5.5 Post-marital movement. Immigration rates: ratio of new names to the total number of names, and net loss/ gain of names, based on baptism records 90 iv page number 5.6 Immigrant sex ratio (parish exogamous marriages) ... 93 5.7 Fertile exogamous marriages resulting in 2 or more children as proportions of total numbers of exogamous marriages 95 5.8 Fertile exogamous marriages resulting in 2 or more children as proportions of total numbers of exogamous partners of each sex 96 5.9 Marriage distances - cumulative proportions 100 5.10 Median marriage distances in miles 101 6.1 Inbreeding coefficients from isonymy data Ill 6.2 Inbreeding coefficients from isonymy data.-- Warkworth, Northumberland Ill V List of Figures page number Fig. 1.1 Crosthwaite Parish ... ... 6 Fig. 2.1a Examples of baptism and marriage record cards - cross-referenced 22 Fig. 2.1b Baptism and dummy marriage record cards - cross-referenced 23 Fig. 3.1 Baptisms and burials in Crosthwaite Parish 1562—1810 ••• ... ... ... ... 35 Fig. 3.2 Baptisms, burials and marriages. 9 year moving averages 36 Fig. 3.3 Changes in the population sizes of areas of Crosthwaite Parish 44 Fig. 3.4 Age and sex distribution of Keswick U.D. per thousand population 47 Fig. 4.1 Breeding population (N) and effective breeding population (Ne) - cohort sizes 53 Fig. 4.2 Mean age at first marriage of women 56 Fig. 4.3 Mean family size 56 Fig. 4.4 Proportion of childless marriages 60 Fig. 4.5 Index of isolation (Nem) 72 Fig. 5.1 Proportions of parish-exogamous marriages to total marriages ... ... ... ... ... 78 Fig. 5.2 Marriage distances in miles at twenty year intervals 99 Fig. 5.3 Orientation of marital movement - parish-exogamous marriages. (a) 1580-99, 1600-19, 1620-39 103 (b) 1640-59, 17O0-19, 1720-39 104 (c) 1740-59, 1760-79, 1780-99 105 Fig. 6.1 Inbreeding coefficients from isonymous marriage data. 20 years intervals from 1560 110 vi ACKNOWLEDGEMENTS I wish to thank Professor E. Sunderland of the Department of Anthropology at Durham University, and Dr R.A. Cartwright, formerly of the same department, for their help and advice during the period this work was undertaken. I would also like to thank Ruth L. Reed who typed the text, and Mr Arthur Corner of the Geography Department drawing office who prepared the figures shown in this thesis. I feel that my father deserves a special word of thanks for his encouragement. Finally, I am grateful to the Medical Research Council who financed this research. vii INTRODUCTION It is obvious to the most casual observer that the appearance of mankind varies considerably throughout the world. Variations in skin colour, hair type, and l»dy build are the most noticeable features which broadly distinguish populations from one another, but it is also recognised that such factors as blood group gene frequencies differ from population to population. Movements of large and small groups of people many thousands of years ago and consequent admixture have made it difficult for any clear classification of human types to be made. In fact, much of today's research into human population variation seems to emphasise the need to study the various factors contributing to human diversity. Controlled breeding experiments on animals such as the fruit fly have enabled the population geneticist to understand many of the mechanisms involved in population variation. It has been possible to control the environment, population sizes, sex ratios and breeding habits of these creatures to such a fine degree that many factors such as natural selection, genetic drift, and the influence of migration can clearly be seen to affect the genetic composition of the experimental populations. Such a great understanding of population genetics was obtained from studies of creatures such as the fruit fly that it was a natural step forward to apply the same kinds of principles to the mechanisms of human population variation, and gene distribution. However it is not merely sufficient to assume that all the factors involved in fruit fly variation work in the same way for man. For example, man has complex rules about marriage and mating which may affect the amount of inbreeding in any population. In very small groups, such as some South American Indian tribes, the prohibition on mating with a close relative may force a man to seize a bride from another community, thus expanding the gene pool.