Female adolescence and reproductive life history of women in the past:
why of this project
Age-at-menarche (i.e., first menstruation) and age-at-first-childbirth are key life history milestones for women.
The age at which menarche and first childbirth occur varies from one woman to the next. Age-based differences are a measure of general health and success in adapting to environmental constraints; while the gap between menarche onset and first childbirth provides insights into perceptions of adolescence, reproductive behaviours, and the way societies are structured.
Secular trends and population variations in the timing of first menstruation and childbirth in contemporary and modern women – from industrialised countries to traditional subsistence-based societies – are matters of interest in many fields, including demography, economics, health, and political sciences. Yet, how the reproductive trajectories differ in women during recent human evolution is a long-standing, but still a largely unexplored issue.
Between the 6th and the 1st millennium BCE, pivotal transformations in the economic and social aspects of human cultures impacted the life histories of ancient populations, shaping the way we live today.
The adoption of an agriculture-based economy and the rise of the first urban centres produced changes in human biology as an adaptative response to new external factors and lifestyles.
The GIRLS Bioarchaeological Project will reconstruct the evolution of age-at-menarche and female reproductive trajectories during these critical transformations, from the emergence of the first sedentary communities –during the Early Neolithic – to the urban societies, until the Roman Imperial Age in Italy.
GIRLS will combine dental histology and histomorphometry with micro-chemistry (via laser-ablation ICPMS) from a novel perspective involving the study of ancient human dental remains. This project will provide unprecedented information on variations in age at the occurrence of menarche and first childbirth in women across six millennia of Mediterranean history.
The identification of dental biomarkers for reconstructing past female reproductive life histories will impact several fields such as biology and life history, tooth histology and biochemistry, archaeology and bioarchaeology, anthropology, and physiology.
GIRLS Bioarchaeological Project’s Research Objectives
research objective #1
Reconstruct the age-at-menarche and age-at-first childbirth in ancient skeletal populations
research objective #2
Propose a cutting-edge model for reconstructing girls’ adolescence in ancient skeletal populations
research objective #3
Reconstructing female adolescence and reproductive life history in ancient Mediterranean societies
GIRLS Bioarchaeological Project’s Work Packages
Work Package #1
identifying new specific biomarkers of menarche and childbirth in wisdom teeth from modern women
Physiological changes occurring in women at menarche and childbirth events are well-established and so are their effects on metabolism, endocrine and hormonal systems, and mineral homeostasis. Similarly, metallome variations indicated substantial changes across menstruation and parturition events. In teeth, such events are recorded and visible as fluctuations in isotope profiles and trace elemental concentrations.
Work Package #1 aims to deeply explore the correlation between variation in dental tissues and trace elemental concentrations at menarche and childbirth events. The PI will characterise menarche and childbirth events through high-resolution odontochronologies of the elemental profiles through laser-ablation inductively-coupled-plasma mass spectrometry (LA-ICPMS) in extracted wisdom teeth (N = 20) from a modern collection with known life history. This first step will allow the research team to create a spatially-resolved model of teeth biochemical markers as a proxy of female menarche onset and childbirth.
applying menarche and childbirth biomarkers to reconstruct reproductive life history in archaeological women’s wisdom teeth
Traditional approaches to the study of adolescence and childbirth in archaeological populations rely upon skeletal developmental stages and markers. Menarche has been tentatively sough in female human remains from the fusion of a few skeletal elements. Yet, this approach does not fully consider the limitations imposed by the Osteological Paradox, whereby the not survivor adolescents are perhaps more likely to have experienced some of the early life stressors that might have caused early or delayed menarche. Childbirth has been tentatively inferred in female skeletal remains from changes in pelvic bones, such as the development of grooves in the preauricular area of the ileum and/or the presence of pits along the dorsum of the pubis. Yet, these pelvic traits might not be specific to parturition events. No less importantly, the age at which a woman had her first child cannot be inferred through the macroscopic analysis of skeletal remains.
Work Package #2 aims to overcome the current methodological limitations of the bioarchaeological research on female reproductive life history by using menarche and childbirth biomarkers on archaeological wisdom teeth. Statistic advanced histo-biogeochemical models built in Work Package #1 will be applied to ancient women (N = 60) – from the Early Neolithic to the Roman Imperial age in Italy – through a histologically-guided high-resolution (LA-ICPMS) analysis of dental tissues.
Work Package #2
Work Package #3
exploring the variation in tempo of female adolescence: modeling the age-at-menarche and age-at-first reproductive event across six millennia of Mediterranean history
Our knowledge of female adolescence and the reproductive life history in the ancient Mediterranean is missing. Most of our understanding of the role and identity of women in Italian prehistory until the Roman Empire comes from material culture – e.g., iconography, funerary practices, artefacts, and, for historical times, funerary epigraphy and historiography.
Work Package #3 aims to model trends of variability of the age at which women experienced menarche and first childbirth in the past. Furthermore, biochemical profiles obtained from archaeological samples will be analysed by using a multi-proxy data set. The data set will include different variables such as (i) osteological evidence (demographic profiles; evidence of health; diet and mobility); (ii) archaeological evidence (chronology; economy; archaeological facies/culture); (iii) funerary and taphonomic evidence (i.e., type of burial; grave goods). For the Iron Age and the Roman Age, (iv) information from historiographical/medical and epigraphic funerary evidence will be included in the data set.
Work Package #3 will bring new light on the differences in resilience, the timing of adolescence, womanhood, motherhood, health, reproduction, fertility, and social roles among diverse archaeological populations in the Italian Peninsula, considering the impact of social, economic, cultural, and ecological systems.