Angélique Janssens

Were Women Present at the Demographic Transition? A Question Revisited

In this contribution I argue that the future of historical demography has much to gain from the incorporation of women and gender into research on the (first) fertility decline in the Western world. Gender, as an explanatory concept, can help construct more complex models for fertility decline in which economic, social and cultural explanations can be connected and which are more sensitive to diversity, to historical context, and to contingency. By perceiving men and women as gendered identities who may have different interests in reproductive outcomes, we will not only restore the necessary agency to historical actors, but we will also see more clearly how many important questions on the fertility decline still remain unanswered.

Faulty genes or faulty parents? Gender, family and survival in early and late childhood in the Netherlands, 1860–1900

According to the famous economist and Nobel prize winner Amartya Sen women have a significant biological advantage over men. Despite this fact women do not always live longer. In todays third world, but also in some areas in Europe at the end of the 19th and the beginning of the 20th century we find so-called excess female mortality. In this paper we examine child mortality in The Netherlands in general and gendered patterns of child mortality in particular. The focus is on differential mortality patterns by gender for infants, older children, and young adults up to age 20 in the second half of the 19th century. The analysis takes place at three levels. We start off with an exploration of sex differentials in mortality at the national level, based on the existing literature. We next examine gender differentials in mortality at the level of several Dutch communities, in the region called Twente, focussing on the differences between the city and the countryside. The final part of the analysis focuses on the micro level of the individual and his or her family in the rural community of Lonneker located in the Twente region. In this part of our study we make use of longitudinal individual level data which are analysed with event history methodologies. Our analysis clearly demonstrates that young women and girls in The Netherlands were not always in a position to fully capitalise upon their greater biological advantage and suffered instead considerable excess mortality. Especially in the rural parts of the country girls had lower survival chances. The individual level analysis confirms the importance of sex in explaining child and adolescent mortality. These gendered mortality risks can however not be attributed to social and economic household characteristics. The analysis also shows that, when death came, it literally affected the entire family. This phenomenon, better known under the label ‘death clustering’, may have been an effect of parental incompetence.

Historical demography and longevity genetics: Back to the future

Research into the genetic component of human longevity can provide important insights in mechanisms that may protect against age-related diseases and multi-morbidity. Thus far only a limited number of robust longevity loci have been detected in either candidate or genome wide association studies. One of the issues in these genetic studies is the definition of the trait being either lifespan, including any age at death or longevity, i.e. survival above a diverse series of thresholds. Likewise heritability and segregation research have conflated lifespan with longevity. The heritability of lifespan estimated across most studies has been rather low. Environmental factors have not been sufficiently investigated and the total amount of genetic variance contributing to longevity has not been estimated in sufficiently well-defined and powered studies. Up to now, genetic longevity studies lack the required insights into the nature and size of the genetic component and the optimal strategies for meta-analysis and subject selection for Next Generation Sequencing efforts. Historical demographic data containing deep genealogical information may help in estimating the best definition and heritability for longevity, its transmission patterns in multi-generational datasets and may allow relevant additive and modifying environmental factors such as socio-economic status, geographical background, exposure to environmental effects, birth order, and number of children to be included. In this light historical demographic data may be very useful for identifying lineages in human populations that are worth investigating further by geneticists.

Clustering of Deaths in Families: Infant and Child Mortality in Historical Perspective

This introduction surveys the field of family clustering of deaths and discusses the contributions in this special issue. The main focus is on mortality in historical contexts. Clustering of deaths in families has been found both in historical and contemporary populations, and we argue that the ‘family approach’ to infant and child mortality yields important and interesting insights for our understanding of different mortality patterns and the mortality transition. The articles in this issue, representing different but complementary approaches to the problem of death clustering, demonstrate that we should be aware of the strong family effects on child health, but also that we need to develop adequate methods for the analysis of this complex phenomenon. Here we discuss several explanations for death clustering, such as different biodemographic factors and those focusing on socioeconomic and cultural variables. We also discuss some of the methodological challenges in studying family clustering, and emphasize the need for comparison and the adoption of common measures.

Longevity defined as top 10% survivors is transmitted as a quantitative genetic trait: results from large three-generation datasets

Survival to extreme ages clusters within families. However, identifying genetic loci conferring longevity and low morbidity in such longevous families is challenging. There is debate concerning the survival percentile that best isolates the genetic component in longevity. Here, we use three-generational mortality data from two large datasets, UPDB (US) and LINKS (Netherlands). We studied 21,046 unselected families containing index persons, their parents, siblings, spouses, and children, comprising 321,687 individuals. Our analyses provide strong evidence that longevity is transmitted as a quantitative genetic trait among survivors up to the top 10% of their birth cohort. We subsequently showed a survival advantage, mounting to 31%, for individuals with top 10% surviving first and second-degree relatives in both databases and across generations, even in the presence of non-longevous parents. To guide future genetic studies, we suggest to base case selection on top 10% survivors of their birth cohort with equally long-lived family members.