Background and some things to consider
In bioarchaeology, the traditional term used for any individual under the age of 18 to 20 (the age at which growth in height mostly ceases for both males and females) is subadult. More recently, there has been a shift to rename the encompassing category as nonadult (see Lewis 2006: 2) to avoid the negative connotation of “sub” in subadult. The smallness and fragility of newborn and infant bones make them much more difficult to excavate and to retrieve for analysis (Baker et al. 2005: 16). At the Libben site in northwestern Ohio, Lovejoy and his colleagues (1977) used fine mesh screens to make sure that small bones from preterm and term infants were recovered from a large ossuary site and, in doing so, were able to retrieve an unheard of high number of infant and children’s bones (discussed later in this chapter).
Methods for the assignment of sex for nonadult human remains exist but there are not yet any standards that can be applied to most populations to assign sex. As Lewis (2007: 48) summarizes it, “sex estimations from nonadult skeletons are notoriously difficult, making associated anthropological techniques unreliable, or forcing us to add greater error ranges to our results in order to account for unknown sex.” She goes on to say that sex estimations in full skeletons from adults can reach as high as a 95% accuracy rate, whereas current methods for estimating sex from infant dentition, skull, or pelvis reaches only 70%. Sex is typically not estimated for subadults for these reasons.
Estimating of age at death is a crucial starting point for the analysis of human remains, and there are many methods to do so (see Chapter 2). Age is largely based on assumed biological characteristics associated with growth and development. Certain biological features appear at particular phases of growth associated with stages such as infancy, childhood, and adult categories (Baker et al. 2005; Scheuer and Black 2000). Changes in growth can be very dramatic during certain ages but these changes in growth can be altered by poor nutrition and disease. Providing an exact biological (or chronological) age is very difficult, but bioarchaeologists are fairly accurate at providing developmental age, allowing us to examine some of the problems with growth and development that might have been experienced by infants.
Paleodemography is the study of the structure of ancient populations based on age and sex to reconstruct what kinds of stressors might have caused early death in different age and sex categories. Bioarchaeologists work with populations of human remains that can essentially provide a death profile, that is, how many individuals died in each age category. This kind of information is useful in knowing how many individuals died at what age. The challenge in using the age distribution of nonadults for a given population revolves around the problems of understanding all the ways that the sample may be biased. From a living population that experiences deaths over time, to the ways that those dead are buried, to the natural alterations that may destroy bone and teeth over time, to which archaeological sites are excavated and how thoroughly they are done so, and finally to what is actually found, retrieved, and analyzed is a “torturous” path (Milner et al. 2008: 571). These kinds of loss of information are important to try to account for. In general, the larger the skeletal population, the more likely it is that the dead are somewhat representing the pattern as it was experienced in real time by the original culture.
Infant mortality rate is the number or percentage of infants who die before their first birthday. One pattern that holds across many different ancient cultures in the New World is that infant mortality was relatively high, estimated to be around 25% (Storey 1985: 520) compared with overall rates in the U.S. today that are around 6% (Haelle 2014). Life expectancy at birth is a function of the distribution of deaths across various age categories for cultures. Life expectancy at birth is based on the mean age at death or the construction of survivorship for all age categories (Milner et al. 2008). Roksandic and Armstrong (2011) provide an easy-to-understand methodology for constructing mean age at death and other aspects of survivorship and chances of making it to old age in any given age group. They rely on developmental stages to divide the age categories for nonadults. As discussed earlier, these include infancy, early childhood, late childhood, adolescence, young, full and mature adulthood, and senile adulthood. This chapter focuses on two related age categories: infancy (birth to about 2 years of age) and young adult females.
A variety of other things likely affected infant survival in the past. Neonates die today from a variety of causes but they are all preventable and include such things as diarrhea, pneumonia, and birth complications (Figure 3.2). Infants are vulnerable to the maternal uterine environment as well as to the environment into which they are born. Infant abuse or child maltreatment may have happened in the past as it does today, but this is very difficult to identify for past populations (Gaither 2012).
FIGURE 3.2 Distribution of deaths for neonates in the first 28 days of life assessed on a global level for the year 2000. From Joy E. Lawn, Simon Cousens, and Jelka Zupan, “4 Million Neonatal Deaths: When? Where? Why?” The Lancet 365, no. 9462 (2005): pp. 891—900. Reprinted with permission.
Definitions of child maltreatment varies from culture to culture, but physical abuse can sometimes by established by the appearance of depression fractures on the cranium or broken ribs or long bones (Martin and Harrod 2015). Infanticide (the intentional killing of infants) and abortion (the intentional killing of the fetus) also may have played a role in past societies but that information is difficult (but not impossible) to reconstruct from bioarchaeological data (Lewis 2007: 92—93). Here one would rely on the finding of preterm infant human remains and the context within which they are located.
What are some issues related to pregnancy, birthing, and maternal health that bioarchaeologists can grapple with? There are a few things beyond the assessment of the health of adult females that provide some clues to the pregnancy and birth experience that include examination of the birth canal size and changes in the pelvis brought on by pregnancy. While bioarchaeologists use the pelvis to distinguish between males and females, it has also revealed important obstetrical information that sheds light on pregnancy and birth. The male pelvis architecture generally creates a smaller inner space (the aspects of the birth canal in females), and the male pelvis shape is more narrow because of the size and angle of the iliac crest of the hip structure (White et al. 2011: 417). Historically, biological anthropologists and osteologists have focused primarily on the pelvic distinctions between males and females and have neglected to evaluate pelves in an obstetric light (Stone In Press).
The female bony pelvis serves several roles (Figure 3.3). Besides housing the birth canal, it has developed throughout human evolution to accommodate
FIGURE 3.3 Female pelvis showing the normal dimensions of the birth canal. “Gray242” by Henry Vandyke Carter — Henry Gray (1918) Anatomy of the Human Body.
bipedality. Nutritional factors, of course, play a part in the development of the pelvis (Walrath 2003).The inlet is the bony passageway through which the fetus must first descend. Often the inlet dimensions are used clinically to identify a contracted pelvis. The pelvic inlet is considered to be contracted if its shortest anteroposterior (from to back) diameter is less than 100 millimeters, or if the greatest transverse (side-to-side) diameter is less than 120 centimeters. The brim index (calculated as the anteroposterior diameter X 100/transverse) is used to describe the overall character of the pelvic inlet and to assign a pelvis to one of the “parent pelvic types” established by Caldwell and Moloy (1938) (see Walrath  for an examination of these dimensions and their implications for female labor and birth). A brim index greater than 95 is classified long oval or anthropoid in which the anteroposterior diameter is greater than the transverse. An index of 90 to 95 is classified as round or gynecoid, and this is where the anteroposterior and transverse diameters are nearly equal. A brim index of less than 90 is classified as flat transverse oval or platypelloid shape, and this is where the anteroposterior is less than the transverse diameter.
What this all means is that females who were nutritionally deprived during growth or who have had certain diseases that have rendered the pelvis contracted may have difficulties during labor (Konje and Lapido 2000). Tague (1994) provided some early studies on pelvic morphology for ancient populations and Stone (In Press) has followed this up with a broader study that clarified the ways that various cultural practices including workloads, diet, nutrition, gender roles, disease, and other factors work to sometimes make pregnancy difficult or even deadly for some females.
Childbirth, also referred to as parturition, has long been thought to leave its marks on the female pelvis. Some researchers report the finding of “parturition pits” along the ventral portion of the pelvis as proof of a female having given birth, but close scrutiny of this literature has failed to support the notion that there are these kinds of specific skeletal alterations that can be traced directly to childbirth (Ubelaker and de la Paz 2012). While things such as parturition pits are sometimes caused by childbirth, other activities also can cause the exact same thing because these pits have been found on some male pelves as well as on females who have never given birth.
Examples of death during childbirth are very rare in the bioarchaeological record. Arriaza and colleagues (1988) reported on 18 (out of 187) females from ancient Chile (dating from about 1300 bc to ad 1400) appeared to have died from the complications of childbirth. These human remains had excellent preservation with naturally mummified tissues still intact, and the unborn or partially born infants were preserved in the cavity of the adult female’s skeleton where the uterus would have been. The authors suggest that acute diseases or cultural practices relating to the birth process may have resulted in the death of both mother and fetus. This was a remarkable and rare find because of the large number of individuals retrieved from these ancient cemeteries and to the excellent preservation. Maternal deaths are often related to hemorrhage, hypertension, and sepsis, all of which are preventable problems, but they are often facilitated by prolonged and obstructed labor, poor nutrition and poor health, or the presence of disease states that compromise the mother (Say et al. 2014).
Maternal health during pregnancy can be compromised by poor nutrition and hard work. Forms of raiding among different indigenous groups in America often were done to take women and children as captives (Cameron 2013). In these cases, captive women and their children could make accommodations and be integrated into households and communities as they were for the ancestral Hodenosaunee (formerly the Iroquois) (Wilkinson and Van Wagenen 1993) or captive women could be kept as outsiders and forced to do hard physical labor as they were in some ancestral Pueblo communities (Martin et al. 2010). Gender roles and sexual division of labor (discussed in Chapter 5) also play a role in how healthy pregnant women may be given their expected roles in subsistence and food production (Larsen 1998). Pregnancy can negatively affect the oral biology ofwomen, and they can be prone to getting more caries (cavities) (Watson et al. 2010). While caries are not necessarily life threatening, they can go on to become large and abscessed, and this can lead to systemic infections.
Harris and Ross (1987: 49) provide a review of ethnographic literature on women in agricultural societies and the kinds of stresses and strains that they are under. With agricultural intensification, females in adulthood labor under the pressure to increase their economic productivity along with decreasing their spacing of births. This places a burden on women to partition their activities among a number of competing tasks. Agricultural females tend to work 7 days a week for approximately 10.8 hours a day to complete all the farming, household, food production, and child-care tasks in their domain (Harris and Ross 1987: 50). These data amassed from historic and contemporary agriculturally based groups are useful in understanding some of the constraints placed on pregnancy and birth in ancient agricultural groups.
Life-history approaches for understanding ancient patterns of maternal and infant outcomes are useful for understanding all the ways that human groups worked to offset poor health and early death. For example, Walker and Johnson (2002) have shown that agrarian societies often have reproductive cycles that are synchronized in ways that maximize mother and infant health. They found that for indigenous groups in the U.S., conception times peaked in July with a second weaker peak in February. These correspond to peak birthing seasons in late spring and fall when food is likely to be more diverse and plentiful. Often ritualized ceremonies around marriage are performed in midsummer when the crops are planted and growing and take less time to cultivate and protect. Low conception during the time of harvesting in the autumn makes good sense because there is a lot of work involved and the harvest must be completed before the first winter frost.
There are certainly many other things to consider when thinking about pregnancy and birth in the ancient world, but these are some of the more major areas that have at least been approached by bioarchaeologists, but much more work is still left to be done in this area of research. Consider this an invitation to delve more into the area by formulating new research questions that can be answered with bioarchaeological data. This is a wide-open area of study as can be surmised from this brief overview. What is known about pregnancy and birth in ancient America is unfortunately not very much, but the focus on the core areas provides some aspects of what moms and their babies were up against.