Editorial: EAA and ISGA congress Vilnius 2022

In Vilnius, Lithuania, from August 24^th to 27^th 2022, The European Anthropological Association (EAA) and the International Society for the study of human Growth and clinical Auxology (ISGA) collaborated for a joint meeting to discuss the latest research in their respective, but cognate, fields of research.

It was of some significance that the 24^th of August marked an anniversary for two important related events: the 30^th anniversary of the freedom of Lithuania from Russian occupation and being exactly six months to the day since the invasion of the Ukraine by Russia. It was not desirable for these learned societies to let these events pass unacknowledged by the wider scientific community of which they are a part. Thus the meeting was punctuated by expressions of solidarity with the Lithuanian people and of condemnation of the Russian invasion of the Ukraine.

The theme of the meeting was “Human Variation and Adaptation in a changing World” and included 200 oral and poster presentations in addition to a number of plenary lectures from invited speakers. Nine of those plenary lectures have been brought together in this special issue of the Annals of Human Biology under the title of “Current Issues in Human Biology.” Together they represent the breadth and depth of research being undertaken as anthropologists, human biologists and auxologists address pertinent topics within this remit. The order in which they are presented in this special issue of the Annals of Human Biology represents the development of analytical methods and their interpretation.

Noël Cameron, President of the EAA and Secretary General of ISGA, opens this series with a review of the relationship between human growth and armed conflict involving three European cities in World War II: London, Oslo, and Stuttgart (Cameron 2023). The outcomes were contrasted to a recent Lancet review of child health and growth in the omnipresent conflicts in many developing countries. The growth of children and adolescents in the industrial nations of the European theatre of war demonstrated an interruption to pre-war positive secular trends in height, weight and age at menarche, associated temporally to the conflict, and a resumption of the trend linked to post-war programmes of renewal and regeneration.

Babette Zemel, from the Children’s Hospital of the University of Pennsylvania, presented the ISGA promoted “James Tanner Lecture,” sponsored by the Society for the Study of Human Biology, in which she discussed the important, and often misunderstood phenomena of “optimal growth” and “tempo of growth” under the title “From growth charts to growth status – how concepts of optimal growth and tempo influence the interpretation of growth measurements.” The term optimal growth is often used to describe a pattern of growth that is only associated with an absence of factors that constrain normal growth or with the health of the individual. Optimal growth may be better defined as the pattern of growth demonstrated by children who adapt best to the prevailing environmental conditions however good or bad they may be. Babette Zemel has produced an in depth discussion of the various approaches to defining “optimal growth” and how growth charts both help and hinder its interpretation (Zemel 2023). Finally, two examples of growth monitoring of pre-term infants and those with genetic conditions are discussed.

William Johnson tackled the problem of latent class trajectory analysis. His comments on these problems involved are pertinent to multivariate analysis of human growth and obesity in children. Latent class trajectory models (LCTM) are to be found with increasing regularity in the human biological literature. These LCTMs are akin to Growth Mixture Models (GMM)), but crucially different in that whilst GMMs assume that the population distribution of individual trajectories is composed of two or more subpopulations, LCTMs do not because they do not capture individual-level growth curves. This leads to analyses of the factors associated with the different group membership and is fundamentally different from investigating how a particular variable is associated with growth per se (Johnson 2023).

Stef van Buuren from the Netherlands continued the theme of growth monitoring and evaluation through charts and individual growth trajectories in his exploration of new approaches to improve the evaluation and prediction of individual growth trajectories (van Buuren 2023). The outcome is demonstrated on a sample of 1985 children each with ten data points from 0-2 years of age. Van Buuren concludes that his “adaptive growth chart” for individual monitoring works with exact ages, corrects for regression to the mean, has a known distribution at any pair of ages and is computationally fast. The method is recommended for evaluating and predicting individual child growth.

Determining the genetic control of height has been the holy grail of auxological research for decades. Height is the result of a combination of both environmental and genetic factors. Whilst different aspects of lifestyle such as health and nutrition are known to have a significant impact on height, some aspects of height determination are encoded in one’s DNA. Twin and family-based analyses have revealed that up to 90% of human height variation is determined by genetic factors. Given the growing body of evidence that height determination is highly polygenic, it is challenging to characterise the full repertoire of genetic contributions to height. Mitchell Conery and Struan Grant from the University of Pennsylvania discuss their polygenic analysis to characterise the full repertoire of genetic contributions to height in their presentation of “A Model Common Complex Trait” for height (Conery and Grant 2023).

The Croatian Islands Birth Study (CRIBS) aims to detect early risk factors for obesity by investigating infant size and early growth trajectories and their association with maternal lifestyle and breastfeeding in a sample of 98 mother-child dyads. The sample from the islands and mainland around Split on the Dalmatian coast are exposed to a traditional Mediterranean diet but that exposure is changing as a result of migration from island to mainland and the availability of cheaper processed food. Jelena Šarac and her team analysed factors related to risk factors for obesity concluding that infant size and early growth in Croatia is in line with WHO standards and risk factors for obesity development were detectable in the first year of life, but not highly pronounced (Šarac et al. 2023). They recommend that more effective BMI monitoring and promotion of healthy diet and lifestyle of women before and during pregnancy is needed in this rapidly changing island environment in the Adriatic.

Stunting has been a continual area of concern and interest in the area of human growth and development. Associations between stunting and poor long-term cardiometabolic and neurocognitive outcomes have been identified and described in low-and-middle-income-countries (LMIC) with the result that the identification of stunting is now recognised as a public health priority. In contrast, in high-income countries, where the prevalence of stunting is much lower, linear growth failure receives less academic and political attention. In this review Joseph Freer and colleagues (Freer et al. 2023) present recent analyses of data from the United Kingdom and outline the evidence for relationships between stunting and cardiometabolic and neurocognitive outcomes in high-income countries.

The assessment of secondary sexual development using Tanner staging methods has always been an area of ethical concerns and a variety of non-invasive approaches have been suggested. In the paper by Juliusson and colleagues (Juliusson et al. 2023), 1285 children aged 6–16 years from the Bergen growth study (BGS2) were examined using objective ultrasound assessments of breast developmental stages and testicular volume in addition to the traditional Tanner pubertal stages. Simultaneous blood samples allowed for measurements of pubertal hormones, endocrine disruptive chemicals, and genetic analyses. This novel use of ultrasound staging of breast development in girls and testicular volume in boys demonstrated a high degree of inter and intra-observer agreement. They concluded that ultrasound provides novel reference data for both breast development and testicular volume on a continuous scale. Endocrine z-scores allowed for an intuitive interpretation of changing hormonal levels during puberty on a quantitative scale, which, in turn, provides opportunities for further analysis of pubertal development using machine-learning approaches.

Lawrence M. Schell and colleagues discuss pubertal maturation and chemical exposure to PFOA, PFOS, PCBs, and DDE/DDT through two systematic reviews (Schell and West 2023). They concluded that most studies of PFOA and PFOS reported either no association or delays in the age at menarche whilst studies of DDT and DDE were more mixed. Reports on PCBs varied by PCB congener group with an equal number of them reporting delays and no association, but one reported an acceleration. Sources of variation in results include the timing of exposure assessment (prenatal vs. postnatal), level of the toxicant and sample size. No obvious pattern to the variation in results could be tied to those sources of variation. The absence of consistent evidence from multiple reports of earlier age at menarche suggests that these toxicants may not be responsible for accelerated sexual maturation in girls. However, comparison of studies is difficult because human populations naturally vary in the variety and levels of exposure and variation in research methods complicate the interpretation of outcomes.

As a series of papers forming this special issue these contributions provide an eclectic view of current human biological research. The various research fields within Human Biology raise a series of important issues covering the way in which our science can be used to record and reflect on the way in which we are facing the challenges of the twenty first century.

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