Post-reproductive Longevity in a Natural Fertility Population

Fertility patterns may be useful markers for rates of biological aging. Based on evolutionary and socio-demographic approaches to historical data from the population of Québec (taken from the Registre de population du Québec ancien at the University of Montreal), we examine the effects of reproduction on longevity. Using Cox hazard models on about 2,000 couples married in the colony before 1740, we show that women bearing their last child late in life had longer post-reproductive lives, suggesting that late menopause is associated with an overall slower rate of aging. Increased parity had an opposite, detrimental effect on women’s post-reproductive survival. On the other hand, husband’s longevity was less sensitive to parity and reproductive history. For husbands increased effective family size (EFS; the number of children who survived up to age 18) in a “compressed” reproductive time-span meant higher chances for survival past age 60. Children may serve as strong economical assets on farmstead during colonization, which would mostly benefit fathers. In a collaborative effort to unveil post-reproductive aging patterns in historical populations, the results are compared to previous analyses conducted on the Utah population database and evolutionary and socio-demographic theories addressed in light of the results

Is There a Trade-off between Fertility and Longevity? A Comparative Study of Three Large Historical Demographic Databases Accounting for Mortality Selection

Frontier populations provide exceptional opportunities to test the hypothesis of a trade‐off between fertility and longevity. In such populations, mechanisms favoring reproduction usually find fertile ground, and if these mechanisms reduce the chances for survival in old age, demographers should observe higher post‐reproductive mortality rates among highly fertile women. We test this hypothesis using complete female reproductive histories from three large demographic databases: the Registre de la population du Québec ancien (Université de Montréal), which covers the first centuries of settlement in Quebec; the BALSAC database (Université du Québec à Chicoutimi), including comprehensive records for the region of Saguenay‐Lac‐St‐Jean (SLSJ) in the 19th and 20th centuries; and the Utah Population Database (University of Utah), including all individuals who experienced a vital event on the Mormon Trail since the early 1800s. From these databases, we extracted, respectively, 5447, 1610, and 11395 women who survived married to age 50. Together, the three samples allow for comparisons over time (Old Quebec versus more recent Quebec and Utah) and space (Quebec versus Utah), and represent the largest data collection used to assess the impact of female reproduction on post‐reproductive survival in a natural fertility context. Using survival analyses controlling for observed and unobserved factors we found a negative influence of parity and a positive influence of age at last child on post‐reproductive survival in the three populations, with remarkably similar effect sizes in the three samples. However, we found little evidence of early fertility effects. We used Heckman’s two‐stage procedure to assess the impact of mortality selection during reproductive years, with no appreciable alteration of the main results. We conclude our empirical investigation by discussing the needs and the advantages of collaborative and comparative approaches

Familial Aggregation of Survival and Late Female Reproduction

Abstract not availabl

Is there a trade-off between fertility and longevity? A comparative study of women from three large historical databases accounting for mortality selection

Frontier populations provide exceptional opportunities to test the hypothesis of a trade-off between fertility and longevity. In such populations, mechanisms favoring reproduction usually find fertile ground, and if these mechanisms reduce longevity, demographers should observe higher postreproductive mortality among highly fertile women. We test this hypothesis using complete female reproductive histories from three large demographic databases: the Registre de la population du Québec ancien (Université de Montréal), which covers the first centuries of settlement in Quebec; the BALSAC database (Université du Québec à Chicoutimi), including comprehensive records for the Saguenay-Lac-St-Jean (SLSJ) in Quebec in the nineteenth and twentieth centuries; and the Utah Population Database (University of Utah), including all individuals who experienced a vital event on the Mormon Trail and their descendants. Together, the three samples allow for comparisons over time and space, and represent one of the largest set of natural fertility cohorts used to simultaneously assess reproduction and longevity. Using survival analyses, we found a negative influence of parity and a positive influence of age at last child on postreproductive survival in the three populations, as well as a significant interaction between these two variables. The effect sizes of all these parameters were remarkably similar in the three samples. However, we found little evidence that early fertility affects postreproductive survival. The use of Heckman's procedure assessing the impact of mortality selection during reproductive ages did not appreciably alter these results. We conclude our empirical investigation by discussing the advantages of comparative approaches

Did grandmothers enhance reproductive success in historic populations? : Testing evolutionary theories on historical demographic data in Scandinavia and North America

Human reproductive success requires both producing children and making investments in the development of offspring. To a large extent these investments are made by the parents of the child, but researchers are now looking beyond the nuclear family to understand how extended kin, notably grandmothers, enhance reproductive success by making transfers to progeny of different kinds. The extent to which kin influence fertility and mortality outcomes may vary across different socio-economic and geographic contexts; as a result, an international comparative framework is used here to sharpen our understanding of the role of kin in reproduction. This chapter assesses the role of grandmothers in fertility outcomes in a comparative historical demographic study based on data from Scandinavia and North America. The individual-level data used are all longitudinal and multigenerational, allowing us to address the impact of maternal and paternal grandmothers on the fertility of their daughters and daughters-in-law, while attending to heterogeneous effects across space and time as well as within-family differences via the use of fixed effects models. We discover broader associations of the paternal grandmother with higher fertility across the four regions. We also find a general fertility advantage associated with the post-reproductive availability or recent death of the maternal grandmother in the four populations. Important variations across regions nevertheless exist in terms of the strength of the association, the importance of the grandmother’s proximity, and the results derived by using fixed effects models. Our interpretation is that grandmothers were generally associated with high-fertility outcomes, but that the mechanism for this effect was co-determined by family configurations, resource allocation and the advent of fertility control

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements