New Prospects for Investigating Early Life-Course Experiences and Health in Archaeological Fetal, Perinatal and Infant Individuals

ABSTRACT Children have become firmly embedded within multidisciplinary investigations of young lives, yet within these studies, the youngest members of past populations persist in lingering on the margins of discussion. Fetal, perinatal and infant lives are tangential; unable to articulate their thoughts and feelings, with their position and role in society typically a product of parental or wider social vectors, these individuals, their experiences, and their roles are complex to decipher. Yet as keepers of both biological and social data – regarding themselves, their mothers and wider community dynamics – these individuals are central in developing comprehensive narratives of infanthood in the past. However, a lack of methodologies for investigating these young lives has been a constant limitation. With recent advancements able to further our understanding of these early life courses, it is now pertinent to focus on fetal, perinatal and infant lives further.

archaeology, where there has been a marked effort over the last two decades to afford and include the voices of those that were once relegated to a brief paragraph of a site report, if indeed included at all (e.g . Lillehammer 1989;Baxter 2005;Finlay 2013;Kamp 2015). This is no more apparent than for fetal, perinatal and infant individuals who were often listed only by skeleton number, with no analysis seemingly conducted. Shifts in praxis have resulted in increasingly inclusive and nuanced interpretations of childhood and infanthood in the past. However, despite the changing landscape of this discipline it is still widely regarded that non-adults receive limited attention in archaeological discourse. Though this may still be true when compared broadly against the number of bioarchaeological studies of adult individuals, there are now thousands of studies focussing on non-adults, with novel research and new developments bringing everincreasing awareness, recognition, and understanding of these young lives. As such, I question whether it is time for us to move away from this general reflection, instead re-focussing our efforts to ensure that all non-adultswhether fetus, infant, child, or adolescentreceive similar attention and consideration.

The earliest life courses
Fetal, perinatal and infant individuals have been identified and recovered from archaeological sites across the world, yet their presence, though often accepted (and expected) has historically not been widely understood. The role and agency of the fetus and infant are now being investigated and questioned more thoroughly from both an anthropological and archaeological perspective (see the edited volume by Han, Betsinger, and Scott (2018) for further discussion) with studies examining the material culture of infancy, epigraphic and literary references, and interpretations of the funerary treatment afford in death to these individuals, all aiding our ability to comprehend these past lives (e.g. Carroll 2011;Harper 2018;Dunne et al. 2019;Cootes et al. 2021;Maltin et al. 2021). However, though we know that older children maintain their own agency, the agency and physical impact that fetal and infant individuals exerted on past populations is substantially more limited. This makes their lives and experiences ever more ephemeral and complex to decipher. Consequently, an advantage of archaeological investigations is our ability to analyze the skeletal remains of the individuals themselves, looking beyond material culture and funerary treatment, which often reflects adult perceptions, tributes, and demands of the infant, to investigate the physiological impacts of their brief but important experiences. The bioarchaeology of infanthood has thus seen exponential growth over the last decade (e.g. Lewis 2007;Halcrow and Ward 2017;Halcrow, Tayles, and Elliot 2018), with a greater understanding of these early beginnings a result of fetal-infant individuals being increasingly recognized and valued as members of past communities.
As such, within bioarchaeology, investigations into the fetal-infant individual, and the nexus between mother and child, are increasing as our interest in the complex relationship between biological and sociocultural variables rises (Adair 2004;Barker 2012;Gowland 2015;Gowland and Halcrow 2020). Bioarchaeological investigations are paramount as the skeleton provides the most direct insight into life course experiences. With it established that both pre-and post-natal life is highly influential in determining later childhood and adult health (Gluckman and Hanson 2006;Barker 2012), there is an increasing need for the study of fetal-infant individuals to investigate the dynamics influencing their life courses, and the development of appropriate methodologies to investigate these. However, despite skeletal remains providing the greatest evidence of these social, cultural, and physical experiences, fetal-infant individuals are still commonly overlooked in our investigations and narratives of 'childhood' the past. Much has been written about these limitations (see Lewis 2007 for discussion) but those typically identified include: (1) Issues with historic archaeological practice and the misidentification (or lack of identification) of these young individuals which rendered them 'absent' from the archaeological record. Where they were identified, they were typically considered to be of limited value.
(2) Lack of experience and understanding of fetal and infant anatomy, and few specialists investigating this age-group specifically.
(3) Methodological limitations which persist, relating to establishing accurate age-atdeath estimations, biological sex estimation, and the identification and interpretation of pathological lesions.
It is these issues that have undoubtedly resulted in the relative lack of studies of fetalinfant individuals when compared to those regarding older children. Indeed, it is disingenuous to assume that all 'children' have received equal attention to date, and just a brief search of the literature will support this. Even within this journal, Childhood in the Past, a search of articles that include 'fetal' in the title will return only one result (though of course, other articles will include fetal individuals within their discussions). Thus, there undoubtedly continues to be deficiencies in our knowledge and methodologies to examine, analyze and interpret these younger life courses. Of course, that is not to say that valuable studies into infanthood do not existthey doand there have been immeasurable advancements in our understandings, not least the fundamental principle of comprehending their distinct, and ever-changing anatomy (e.g. Baker, Dupras, and Tocheris 2005;Scheuer and Black 2000;Blake 2018). However, it is still true that there are simply fewer fetal-infant studies in comparison to those focussing on older age groupings, and major issues regarding the construction of biological profiles, and understanding aspects of these brief lives, prevail. Despite this, it is encouraging to see that both the number of investigations, and investigators, focussing on fetal-infant individuals is ever increasing (Figure 1).

New developments and continuing challenges
Fundamental limitations of physiological analysis of fetal-infant individuals continue to endure, resulting frequently in vague understandings of these early points of life; where we aim to generate results with higher resolution, interpretations are inevitably littered with caveats of potential population variation and methodological inaccuracies, limitations, and errors. Yet, despite these lingering challenges, there have been several exceptional developments within the broader discipline of bioarchaeology within the last few years, which will undoubtedly lead to changes in the way we approach and conduct fetal-infant studies. These investigations have furthered our understanding of, and helped address issues related to: biological sex estimation (e.g. Gowland et al.  Helfrecht et al. 2020). Such methods are improving and increasing our ability to distinguish between and specify exact moments of the early life course, and the events experienced, both pre-and post-natally.
Indeed, it is well established that prenatal life is as critical as any early post-natal experience to offspring cognitive, physical, and health success. Consequently, the fetal and early infantile period is the most sensitive to a range of biological, social, and environmental factors. This means that these young individuals act as both barometers for overall population health, as well as providing unrivalled insights into individual experiences of health, birth, and death in archaeological and historical societies. Yet, there continue to be challenges in fetal-infant investigations attempting to explore these aspects of early life. As such, I propose that there are four key limitations and research areas where we should focus our attentions to enable further insights into the pre-and post-natal life course. These are age estimation methodologies, the identification of growth disruption, continued exploration of birth experiences, and the identification of pathological from physiological new bone formation.

Age estimation methodologies
Concerns around the applicability and comparability of ageing methodologies, the use of dental and skeletal techniques to assess/measure development, and the correlation of these developmental stages with age prevails. Given intrinsic and extrinsic variables, the applicability of methods to geographically, temporally, and culturally diverse populations is questioned. Furthermore, some existing methods traditionally applied to age fetal-infant individuals have intersecting age categories, limited sample sizes, and include individuals within their data of unknown age, leading to fundamental questions around the accuracy and suitability of these methods. New aging techniques are continuing to be developed, but more investigations interrogating the estimation of age, using a range of skeletal elements and individuals are required.

The identification of growth disruption
The identification of growth disruption is problematic, relying on the accurate metric assessment of fetal-infant skeletal remains, and comparison of results against an established age-estimate, the limitations of which I discuss previously. Where large differences between skeletal growth and age can be identified, growth disruption can be insinuated, but we are potentially missing those who have experienced acute or limited growth disruption. These investigations are important as growth, and the disruption of normal growth, are indicative of both pre-and post-natal experiences, and can contribute to discussions of physiological stress, poor health, maternal wellbeing, and birth experiences and outcomes (such as prematurity and small for gestational age (SGA)). Consequently, evidence of growth disruption, even in these very young individuals, is essential to identify if we are to truly develop comprehensive interpretations of fetal-infant lives.

Exploration of birth experiences
Subsequently, questions surrounding birth experiences and outcomes, and the identification of these (e.g. SGA, intrauterine growth restriction (IUGR), still birth or prematurity) deserve increasing recognition and attention. Stillbirth, prematurity, SGA and IUGR are central concerns surrounding pregnancy today, but these vital early life experiences are seldom considered in an historical context. These birth outcomes are associated with a multitude of health conditions and are important aspects to consider in relation to both fetal-infant and maternal health. Despite infant mortality rates known to be much higher in the past than those today, the cause of these inflated levels, and the relationship between birth experiences and mortality rates, remains unknown. Methodological developments (e.g. histological analysis of bioerosion (Booth, Redfern, and Gowland 2016)) are aiding these discussions, but further investigation is required.

Identification of pathological new bone formation
Finally, the identification of pathological new bone formation, and distinguishing this from physiological new bone formation as a result of rapid growth, continues to be a major limitation. Bioarchaeological studies infer poor health from the presence of pathological lesions on skeletal remains. Subsequently, pathological changes are considered to represent physiological responses to detrimental onslaughts. Despite this established association, little attention has been afforded to the identification and interpretation of pathological lesions in fetal-infant individuals. This is a result of methodological challenges with the distinction between pathological and normal changes in those younger than 4 years old, highly problematic (Lewis 2007). Currently, macroscopic methodologies for assessing and identifying pathological lesions are inadequate. Identifying and interpreting evidence of pathological changes in fetal-infant individuals is thus, both subjective and variable, with little standardization or comparability between investigations. Comprehension of pathological changes is important to aid discussion of intra-and extrauterine health disruption, as well as providing proxies for maternal and community health.

Bringing up baby
These current discussions and developments within fetal-infant bioarchaeology are, of course, particularly pertinent to me personally. As a bioarchaeologist, dedicated to understanding the lives and experiences of the very young in the past, I am acutely aware of the limitations continuing to impede and cast doubt on fetal-infant studies. My previous research has highlighted the need for a holistic approach to the investigation of fetal-infant individuals, exploring evidence of growth disruption and pathological changes in a sample of over four hundred individuals. Yet, as the concerns mentioned above indicate, our interpretations and knowledge of these past individuals and communities can be significantly improved. Given the increasing number of fetalinfant individuals identified, excavated, and assessed, it is essential that we begin to address these questions.
Consequently, it is my aim to do this through my new research project: 'Bringing up Baby: Investigating early life course experiences and health in fetal and infant individuals from archaeological and historical populations in Britain'. The project builds on important research questions that have arisen from my continued exploration of the fetal-infant life course in the past. The project will simultaneously consider skeletal and contextual data to explore relationships between detrimental early life experiences and the sociocultural worlds in which the individuals developed and/or lived. This research is multidisciplinary in its approach, utilizing some of the new scientific methods detailed previously, to investigate socially and culturally driven enquiries and explore the lived experiences of fetal-infant individuals in past societies. In particular, my project seeks to consider evidence of detrimental birth outcomes and skeletal pathology, establishing methods by which to investigate these factors, and documenting changes in fetal-infant health over time, to explore socially and culturally regulated variables impacting the fetal-infant life course.

Fetal-infant research: privileges, problems and ethics
Though it is anthropologically, archaeologically, and clinically important to investigate the early life course, as researchers in this field we must never forget the importance of ensuring this work is conducted in an ethical, appropriate, and sensitive way. The discourse of infant morbidity and mortality is particularly emotive and regardless of whether we are working with archaeological, historical, or medical collections, the privilege of being able to investigate these individuals should always be acknowledged. Within bioarchaeology, discussions around the ethical excavation, curation, and analyses of human remains are ongoing and multifaceted, often context and resource dependant (see Squires, Errickson, and Márquez-Grant 2020 for extensive discussion). Furthermore, the nature of analyses (whether they are destructive or passive), and the ownership of data and human remains, are leading to ongoing discussions over the power dynamics of who constructs narratives of the past (e.g. Fuentes 2020; Tsosie et al. 2021). Thus, investigations of fetalinfant individuals are not only particularly emotive, given contemporary perspectives regarding the vulnerability of these individuals, but must ensure that they are cognizant of the archaeological/historical context of these collections. This is particularly pertinent for those of us who have, and continue to, work with medical collections, where in many instances targeted collection, structural violence, and racism have all been central in their formation (Gindhart 1989;Nystrom 2014;Vanderbyl, Albanese, and Cardoso 2020). This is something that is being more universally discussed within bioarchaeological dialogue, yet the acknowledgement that this has occurred for some of our collections of infants and children too is perhaps particularly distressing. This is something with which I must personally reckon with also, having previously analyzed medical collections of vague and likely violent provenance. Therefore, as we continue our investigations, and further our knowledge and understanding of these early life courses, it is essential that we acknowledge, address, and consider the implications of these practices where applicable. Subsequently, all investigations of fetal-infant individuals should be conscientious of individual experiences, emotions, and agency, critical of both the methods and contexts of future investigations. Furthermore, it is imperative that as researchers, scientists, and humans, we never forget our own privilege in having the opportunity to conduct such investigations into these brief but important lives.

Conclusion
The first 1000 days of lifefrom conception through to infancyhave been recognized as the most fundamental and influential in shaping future growth and health. Hence, the skeletal analysis of fetal-infant individuals can now provide unparalleled insights into pre-and post-natal experiences within different sociocultural, temporal, and economic milieus. Furthermore, the development of life course models (e.g. Developmental Origins of Health and Disease hypothesis) has recognized that both short-and longterm health outcomes are not a product of genetic endowment alone, but are also regulated by environmental, social, cultural and psychological factors experienced in early life. As such, assessment of the skeletal remains of these young individuals is paramount to understand temporal changes in fetal-infant health over time, as well as being critical for understanding health implications for infants today. Establishing clearer methodologies for the accurate estimation of age, growth disruption, birth outcomes and pathological identification is vital for a comprehensive insight into fetal-infant lives in the past. With an enduring legacy of under-representation and a paucity of knowledge still existing in regards to aspects of assessment of fetal-infant individuals, this is a critical and emerging area of research that requires further ethical and sensitive investigation and engagement from the bioarchaeological community.

Disclosure statement
No potential conflict of interest was reported by the author(s).

Notes on Contributor
Claire Hodson was awarded a British Academy Postdoctoral Research Fellowship in 2020 for her project 'Bringing up Baby', to be held at the Department of Archaeology, University of Reading (Grant Award: PF20\100096). Claire's research has long been focussed on the fetal, perinatal and infant life course, investigating ways in which growth and health of these individuals was disrupted in past archaeological societies. Claire is currently the membership secretary for the Society for the Study of Childhood in the Past.