Bacterial bioerosion of bone may help identify stillborn infants from the past

New research using novel microscopic investigation of bacterial bioerosion of archaeological bone has shown that you can differentiate between stillborn and post-newborn babies. This was most exciting to me as offering a means to contribute to the debate of the interpretation of infanticide in the past, through an investigation of time of death.

Bioerosion is the removal of mineralised substrate through the action of organisms, and has been found to be the most common form of microbial attack of archaeological bone (Figure 1). The author of this new research, Tom Booth from the Natural History Museum, notes that although it was once believed that soil bacteria caused most of this bioerosion in bone, it is the gut microbia that is responsible for corpse putrification that causes this process. Based on the findings that it is the bacteria inside the body that produces this bioerosion, the author thought that this could be useful for assessing different mortuary treatments of the body.

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Figure 1: Transmitted light micrograph of a human fresh bone transverse femoral thin section (top) demonstrating perfect microstructural preservation and a typical archaeological femoral section (bottom) where the internal microstructure has been extensively altered by bacteria (from Booth et al., 2015).

To investigate if there is any relationship between bacterial bone bioerosion and funerary treatment, Booth undertook a microscopic analysis of human bones from European prehistoric (4000 B.C. – A.D. 43) and British historical (A.D. 43 – present day) sites. These two assemblages were used as they have been found to have different funerary practices, with the historic period sites practicing burial soon after death, whereas the prehistoric sites have more variable mortuary practices, sometimes including postmortem modification. E.g. Booth and colleagues’ work that found evidence for mummification in Bronze Age Britain using this microscopic method has recently received media attention.

This research shows that irrespective of burial environment, including antiquity or soil type, there was immaculate histological preservation of almost half of the neonatal samples. This is interpreted as the result of sterility of stillborn infant intestinal tracts resulting in the bones being unaffected by the process of bacterial tunneling. In addition, most (12/15) of the unbioeroded newborn samples are from historical cemeteries where most of the other samples had been extensively bioeroded. A previous experimental study by White and Booth using pigs found that bone from stillborn neonatal carcasses had immaculate histological preservation due to the intrinsic sterility of newborn infant intestinal tracts.

Booth found that the soil type had no relationship with bacterial bioerosion. There was evidence for variation in bacterial bioerosion among the later prehistoric assemblages argued to be “consistent with the knowledge that these individuals were subject to variable early post mortem treatment that exposed the bones to diverse levels of bacterial attack.” Bacterial bioerosion in the historical assemblage was high, consistent with that expected within bones of intact bodies that had been interred soon after death.

The use of this novel method to differentiate stillborn vs post-newborn infants can contribute to extending our knowledge of the cause of death during the most crucial time for mother and child in the past, and may also have useful applications for the study of cultural beliefs around stillbirth and post-neonatal death.


Booth, T. J., A. T. Chamberlain and M. P. Pearson (2015). “Mummification in Bronze Age Britain.” Antiquity 89(347): 1155-1173.

Violent deaths of children during a time of imperial decline in Ancient Peru

A new study has found that children suffered violent deaths during a turbulent time of severe social stress and drought following the “collapse” of the Wari empire in the Late Intermediate Period (1000-1400 C.E.) in the Peruvian Andes.

A research chapter by Tiffiny Tung from Vanderbilt University and colleagues has shown the locations of fractures predominantly on the left side of the posterior crania strongly suggest that these injuries were not accidental. The severity of fractures with large pieces of bone dislodged indicate that these were formed from violent blows in a standardised manner (Figure 1).

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Figure 1: Top row, Cranium 20: Perimortem trauma on the left side (left photograph) and two perimortem fractures on the posterior (right photograph). Bottom row Cranium 68: perimortem trauma on the left side (bottom left photograph is posterior view, bottom right photograph is posterior-lateral view). Both are from the Late Intermediate Period component at the Vegachayoq Moqo sector at Huari (photo from Taung et al. 2016, figure 10.4, page 207)

The prevalence of these types of trauma in the Late Intermediate Period (n=4/8) is statistically significantly higher than the preceding period where there was no evidence for perimortem trauma in the Wari-era children (N=39).

The authors state that “ … lethal trauma—or any kind of cranial trauma—on children is exceedingly rare in the Andes (except in cases of child sacrifice), so it is particularly revealing of the unstable sociopolitical conditions in the LIP [Late Intermediate Period] in the Ayacucho Basin.”

Previous work by Tung (2008) has shown that more than two thirds of the adults also experienced cranial trauma attesting to a climate of violence during the Late Intermediate Period in this region.

Carbon isotope ratios from enamel apatite and dentine collagen show that maize consumption decreased during this time, and that there was unequal access to maize between the sites, which the authors argue may have led to social tension through inequality.

The authors state that a combination of factors may have contributed to the high level of lethal trauma in the children. The Wari empire represented the first expansive empire in South America, which maintained control of the area from the northern Andes of Peru, to the central Peruvian coast, to the Moquegua Valley in the far south (Schreiber 1992). After its collapse there is evidence for a major transition in social organisation, and increase in competition for scarce resources, supported by the change in patterns of maize consumption. The pattern of trauma found does not suggest child abuse, but rather that the aggressors intended to kill them, argued by the authors to have occurred during raids in the communities.

Although there is no way to definitively tell what caused the increase in lethal trauma in the children, what is clear is that the turbulent times during the imperial collapse likely contributed to their violent deaths.



Schreiber, K. J. (1992). Wari imperialism in Middle Horizon Peru. Ann Arbor: Museum of Anthropology University of Michigan.

Tung, T. A. (2008). Violence after imperial collapse: A study of cranial trauma among Late Intermediate period burials from the former Wari capital, Ayacucho, Peru. Nawpa Pacha, 29, 101–118.