A demographic study of Crosthwaite parish: some genetic implications

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.