Testing times: identifying puberty in an identified skeletal sample

Proposed complementary osteological indicators: Advancing the estimation of puberty stages in Bioarcheology

OBJECTIVES

The study of puberty is a well-established area of bioarcheological research, which greatly enhances our understanding of adolescence and growth in the past. Since the publications of Shapland and Lewis' works, which have become "standards" for estimating puberty in skeletal material, no additional osteological indicators of puberty have been proposed. Nevertheless, clinical practice constantly develops skeletal maturation markers that could be useful in bioarcheology. This study aims to assess the applicability and reliability of novel puberty indicators as a complementary tool to estimate puberty in skeletal remains.

MATERIALS AND METHODS

Four new maturation markers including spheno-occipital synchondrosis, humeral head ossification, calcaneal apophysis ossification, and mandibular premolar mineralization were selected and applied to a sample of 85 adolescents from pre-Roman southern Italy (Pontecagnano, 7th-4th BCE).

RESULTS

Despite some limits in adapting the original clinical methods to osteoarcheological material, the use of these novel skeletal indicators had moderate to excellent scoring repeatability and an overall high agreement with the puberty and menarche status previously estimated with standard methods. These results encourage us to apply these markers in bioarcheology. In some cases, minor adaptations of the original scoring systems are suggested to enhance reliability.

DISCUSSION

Including the proposed indicators in routine puberty data collection allows us to refine puberty estimation and improve the ability to identify key growth milestones in poorly preserved skeletons. Further application to osteological collections with diverse chronology and geographical differences is needed to assess how and to what extent the newly proposed maturation markers perform.

Exploring adolescence as a key life history stage in bioarchaeology

Adolescence is a unique period in the life history of an individual. It is characterized by a myriad of changes that bioarchaeologists are only just coming to appreciate, related to sexual maturation, linear growth, immunological transformation, and emotional and cognitive development. New methods allow us to measure this age of transition through the stages of the adolescent growth, as a proxy for the physical development associated with sexual maturation (puberty). This review outlines ways bioarchaeologists may draw on research developments from the fields of human biology, evolutionary theory and neurobiology to advance a more holistic approach to the study of adolescence in the past. It considers current theoretical and analytical approaches to highlight the research potential of this critical stage of life history. This synthesis integrates the most recent research in the medical sciences concerned with body and brain development, and outlines the biological processes involved with sexual and physical maturation of the adolescent. The goal of this review is to help inform potentially rewarding areas of research that bioarchaeologists can contribute to and draw from, as well as the challenges and limitations, theoretical and methodological questions, and ways in which we can develop the study of adolescence in the discipline going forward.

Reproductive life histories: can incremental dentine isotope analysis identify pubertal growth, pregnancy and lactation?

BACKGROUND

There are few reliable osteological indicators to detect parity or infer puberty in skeletal remains. Nitrogen (δ¹⁵N) and stable carbon (δ¹³C) isotope ratios in human tissues can be affected by metabolically unbalanced states engendered by pregnancy or rapid growth, offering potential biomarkers.

AIM

This pilot study explores the potential of incremental dentine-collagen isotope ratio analysis to identify puberty and gestation.

SUBJECTS AND METHODS

Incremental dentine δ¹⁵N and δ¹³C profiles were produced by analysing third molars extracted as part of dental treatment of 10 individuals living in Sudan. Demographic and anthropometric data at the time of tooth extraction was available. Medical histories were unknown.

RESULTS

Isotopic signatures potentially related to pubertal growth, with an average δ¹⁵N reduction of 0.78 ± 0.29‰, are indicated. Six isotopic signals suggestive of pregnancy, with an average δ¹⁵N decrease of 0.48 ± 0.22‰, are also observed. The timing, speed and amplitude of post-partum δ¹⁵N patterns seemingly infer infant feeding practices and maternal nutritional status.

CONCLUSION

This pilot study highlights the potential of incremental dentine isotope analysis for the reconstruction of early reproductive histories in skeletal remains. However, controlled studies with a larger human cohort are needed to validate these findings, establish isotopic signals linked to puberty and lactation, and improve chronology accuracy.

Approaches to osteoporosis in paleopathology: How did methodology shape bone loss research?

OBJECTIVE

This paper will review how different methods employed to study bone loss in the past were used to explore different questions and aspects of bone loss, how methodology has changed over time, and how these different approaches have informed our understanding of bone loss in the past.

MATERIALS AND METHODS

A review and discussion is conducted on research protocols and results of 84 paleopathology publications on bone loss in archaeological skeletal collections published between 1969 and 2021.

CONCLUSIONS

The variety in research protocols confounds accurate meta-analysis of previously published research; however, more recent publications incorporate a combination of bone mass and bone quality based methods. Biased sample selection has resulted in a predominance of European and Medieval publications, limiting more general observations on bone loss in the past. Collection of dietary or paleopathological covariables is underemployed in the effort to interpret bone loss patterns.

SIGNIFICANCE

Paleopathology publications have demonstrated differences in bone loss between distinct archaeological populations, between sex and age groups, and have suggested factors underlying observed differences. However, a lack of a gold standard has encouraged the use of a wide range of methods. Understanding how this array of methods effects results is crucial in contextualizing our knowledge of bone loss in the past.

LIMITATIONS

The development of a research protocol is also influenced by available expertise, available equipment, restrictions imposed by the curator, and site-specific taphonomic aspects. These factors will likely continue to cause (minor) biases even if a best practice can be established.

SUGGESTIONS FOR FUTURE RESEARCH

Greater effort to develop uniform terminology and operational definitions of osteoporosis in skeletal remains, as well as the expansion of time scale and geographical areas studied. The Next-Generation Sequencing revolution has also opened up the possibility of ancient DNA analyses to study genetic predisposition to bone loss in the past.

Coming of age in the Netherlands: An osteological assessment of puberty in a rural Dutch post-medieval community

OBJECTIVES

The objective of this study is to apply pubertal stage estimation methods to a sample from a rural community: the post-medieval Dutch skeletal collection from Middenbeemster. Puberty is a key developmental period involving transition to physical adulthood with broad societal relevance through its impact on fertility, morbidity, and mortality.

MATERIALS AND METHODS

Individuals (n = 55), including 27 of known sex and age-at-death, between the ages of 8 and 25 years were assessed for six skeletal markers indicative of pubertal growth spurt. Recent novel osteoarchaeological methods from Shapland and Lewis are used to reconstruct the timing and duration of pubertal stages.

RESULTS

Pubertal acceleration occurred earlier in females (10.38 years, n = 8) than males (13.30 years, n = 6), whereas maturation occurred later in males (21.36 years, n = 11) than females (19.30 years, n = 5). Onset appears earlier and completion later compared to other archaeological skeletal samples with osteoarchaeological evidence of puberty. Age shortly after menarche was reconstructed at 20.45 years, substantially later than historic records and bioarchaeological research reports suggest.

CONCLUSION

This early onset and late completion caused a "stretch" of the overall duration of puberty compared to other collections, especially of the last three stages. This prolonged development is reflected in historically known social expectations for the Netherlands, for example, that marriage and children should not occur before about 22-23 years of age. Increasing the range of past peoples with puberty stage reconstruction will permit more insightful interpretations of the biological and cultural patterns of this important life stage.