https://orcid.org/0000-0003-3740-2620
![Sample our Social Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110822/TOC-Subject-Sample-2021-Social-Sciences.jpg"})
ABSTRACT
The digital age allows data collection to be done on a large scale and at low cost. This is the case of genealogy trees, which flourish on numerous digital platforms thanks to the collaboration of a mass of individuals wishing to trace their origins and share them with other users. The family trees constituted in this way contain information on the links between individuals and their ancestors, which can be used in historical demography, and more particularly to study migration phenomena. The case of 19th century France is taken as an example, using data from the family trees of 238,009 users of the Geneanet website, or 2.5 million (unique) individuals. Using the geographical coordinates of the birthplaces of 25,485 ancestors born in France between 1800 and 1804 and those of their descendants (24,516 children, 29,715 grandchildren and 62,165 great-grandchildren), we study migration between generations at several geographical scales. We start with a broad scale, that of the departments, to reach a much finer one, that of the cities. Our results are consistent with those of the literature traditionally based on the parish or civil status registers. The results show that the use of collaborative genealogy data not only makes it possible to support previous findings of the literature, but also to enrich them.
Acknowledgments
The authors would like to thank two anonymous referees and the Editor Angélique Janssens for their helpful comments. A preliminary work was presented during the ‘Science XXL’ days organized in March 2017 at the French Institute for Demographic Studies (INED). We thank Olivier Cabrignac and Jérôme Galichon for their help on data exploration, as well as the participants for the discussions we had then, which motivated some of the elements presented in this study. We also thank the members of INED’s History and Populations Unit for their comments. We benefited from fruitful discussions with the participants of the ‘UseR’ conferences (Budapest, May 2018), the ‘R meeting’ (Rennes, July 2018), the ‘XXIX International Biometric Conference’ (Barcelona, July 2018), and the ‘Eco-lunch’ seminar (Marseille, September 2018).
Disclosure statement
No potential conflict of interest was reported by the authors.
Notes
1. The labor market is used to define a migrant. Shryock and Siegel (Citation1976, p. 374) refer to the existence of increasing opportunity costs of distance from home to work, which can lead to a change of residence when it becomes too high.
3. The website’s users can choose between publicly sharing their family tree or keep it private. We do not have access to the latter, so that our analysis only uses publicly shared family trees.
4. According to Geneanet, 40% of their records relate to French data.
5. As reminded by Fleury and Henry (Citation1958), this period corresponds to the uninterrupted recovery of death, marriage and death records in the whole of France.
6. More details can be found in Appendix A.
7. There is evidence of child labor at younger ages (Fauve-Chamoux, Citation2004), which may suggest that a lower threshold could be established. Lowering the threshold to 14 years of age only changes the results at the margin and leads to the deletion of 451 observations.
8. As the objective is to observe internal migration from one generation to the next, we consider each ancestor born between 1800 and 1804 in metropolitan France and follow all his or her descendants present in the data. Thus, the child of a couple will be present twice in the data if information on their parents is available. It should be noted, however, that the numbers of 24,516 children, 29,715 grandchildren and 62,165 great-grandchildren refer to unique individuals in the database.
9. Currently, there are 101 department in France, 96 of which are located in the European territory, so-called ‘metropolitan France’.
10. As we are interested in internal migrations in France, we only focus on French territory. In addition, we are looking at the places of birth of the descendants who were born outside the department of their ancestor. So, when computing the density of births for individuals born outside a given department, we know a priori that the birthplace of these individuals cannot be found inside that department. This information should be accounted for when estimating the density of births, to avoid a border bias. The procedure is explained in Charpentier and Gallic (Citation2016).
11. See more details in Appendix B regarding the methodology used to compute distances.
12. However, the number of descendants born outside France in the data is low, with only 261 observations.
13. It should be noted that people who had no children are excluded from this analysis.
15. The analysis of migration at the level of the municipalities is in principle made possible by the individual nature of the data. It should be noted, however, that the initial restrictions in this article (intended to focus only on individuals born in the early 19th century and their descendants) only provide a glimpse of migration at the micro level. Indeed, since annual births in small villages are not very numerous, there are few movements observable on such a small scale, with the exception of Paris. Collaborative genealogical data could, however, prove to be an excellent means of observing migrations on a very fine spatial scale, provided that a larger population of ancestors is considered than that chosen in this study.
16. Again, we exclude the department of Paris for visual concerns, so that the high percentage associated with this department does not inflate the scale.
17. The distance between the regions and Paris is calculated using the distance separating the centroids from the regions.
18. Actually, Victor Hugo had more children, but they are not represented in Figure A1(a) for simplicity.
19. Since 1990, French territory is divided in administrative regions called ‘départements’. Currently, there are 101 departments, 96 of which are located in the European territory. We focus on these 96 European French departments.