Milk of ruminants in ceramic baby bottles from prehistoric child graves

[NNadir]

The paper I'll discuss in this post is this one: Milk of ruminants in ceramic baby bottles from prehistoric child graves (J Dunne et al Nature 574, 246–248 (2019)).

It is, I think, a good thing that we found out that the most modern approach to infant nutrition is breast feeding. Chemical analysis of human breast milk has shown - aside from chemical toxins associated with our modern life style, for example the common presence of brominated diphenylether flame retardants in the women who recycle our electronic stuff in China - that it is unique among all animal species. One of the major differences concerns lipids; human breast milk contains for example certain polyunsaturated lipids such as EPA, eicosapentenoic acid, and the related DHA and aracadonic acid which is thought to offer certain developmental neurological advantages owing to their propensity to undergo cycloadditions to make important molecules such as prostaglandins and certain hydroxylated species. I'm not sure that I know the precise mechanisms of the neurological effects, but I do know they are real.

I used to joke with my wife that I hoped that my sons would wean before they went to college; I'm sure both of them breast fed at least past their third birthday, although they ate other foods before their first birthday. They're men now, and it's possible, I think, it all worked out for the better. They're pretty smart guys.

Anyway, it appears that the problem of feeding children nonhuman animal milk has a very long history according to this paper. From the abstract which is open sourced:

The study of childhood diet, including breastfeeding and weaning, has important implications for our understanding of infant mortality and fertility in past societies1. Stable isotope analyses of nitrogen from bone collagen and dentine samples of infants have provided information on the timing of weaning2; however, little is known about which foods were consumed by infants in prehistory. The earliest known clay vessels that were possibly used for feeding infants appear in Neolithic Europe, and become more common throughout the Bronze and Iron Ages. However, these vessels—which include a spout through which liquid could be poured—have also been suggested to be feeding vessels for the sick or infirm3,4. Here we report evidence for the foods that were contained in such vessels, based on analyses of the lipid ‘fingerprints’ and the compound-specific ?13C and ?13C values of the major fatty acids of residues from three small, spouted vessels that were found in Bronze and Iron Age graves of infants in Bavaria. The results suggest that the vessels were used to feed infants with milk products derived from ruminants. This evidence of the foodstuffs that were used to either feed or wean prehistoric infants confirms the importance of milk from domesticated animals for these early communities, and provides information on the infant-feeding behaviours that were practised by prehistoric human groups.

From the introduction to the paper, which is probably not open sourced:

The study of past infancy—including infant care, breastfeeding and weaning practices—provides valuable information on population demographics and health, reproduction rates, mortality patterns and fertility of individuals of past societies. Today, feeding practices for babies can be attributed to various ecological and socioeconomic constraints and cultural factors, such as health beliefs and food taboos1,5,6. Prehistoric humans probably practised a range of infant-feeding behaviours2,3,4,6,7, which had profound consequences for the biological and social wellbeing of the infants. Ethnographic, historical and social studies have shown differences across the breastfeeding phase, the nature of the addition of supplementary foods (during weaning) and the timing of cessation of breastfeeding1,5,6,8.

Breastfeeding is integral to infant care in all human groups and fundamental to the mother–infant relationship4. Breast milk provides an infant with all of the macro- and micronutrients that are required to sustain growth for the first six months of life9, together with bioactive components, which protect the infant from pathogenic organisms and facilitate the development and maturation of the immune system10. The introduction of energy and nutrient-rich, easily digestible, supplementary foods in infant feeding (that is, during weaning) is unique to humans11,12. Supplementary foods are generally introduced at around six months of age, when the metabolic requirements of an infant exceed the energy yield that the mother can provide through milk, contributing to the infant diet as chewing, tasting and digestive competencies develop1,12,13.

Apparently vessels that are believed to have been ceramic "baby bottles" were placed in the graves of children buried in prehistoric Germany:

he widespread use of animal milk, either to feed babies or as a supplementary weaning food source, became possible with the domestication of dairy animals during the European Neolithic14, during which time generally improved nutrition contributed to an increased birth rate, with shorter inter-birth intervals, that resulted in considerable growth of the human population: the so-called Neolithic demographic transition15. Broad trends identified from the Neolithic to Iron Age in Central Europe suggest that supplementary foods were given to babies at around six months of age and weaning was complete by two to three years of age3.

Possible infant-feeding vessels that are made from clay first appear in Neolithic Europe. One of the earliest of such finds is a Linear Pottery Culture feeding vessel from Steigra, Germany, that has been dated16 to around 5500–4800 BC. These unique vessels, which have a small spout through which liquid could be poured or suckled, come in many forms and sizes and occasionally have a zoomorphic design (Extended Data Fig. 1). They become more common in Central Europe during the late Bronze and early Iron Age4 and are found in settlements, as stray finds, and in graves (particularly those of children), which strongly suggests that they were feeding or weaning vessels for infants.

The precious nature and often small openings of these vessels makes their sampling for organic residue analysis extremely challenging. However, infant-feeding vessels that have an open, bowl form, found in graves from cemeteries of Dietfurt-Tankstelle and Dietfurt-Tennisplatz in Germany, have recently become available for chemical analysis. The graves are part of a large early Iron Age cemetery complex (dating to approximately 800–450 BC) found in the lower Altmühl valley in Bavaria, Germany, with Dietfurt-Tankstelle encompassing 99 burials in 72 graves17 and Dietfurt-Tennisplatz containing 126 burials18. Child grave 80 at Dietfurt-Tennisplatz contained an east–west-oriented inhumation of a young child (0–6 years old), who had a bronze bracelet on the left arm, and in which feeding vessel 1 (Fig. 1a) was placed at the child’s feet18.

A graphic:



The caption:

a, b, Drawings of child graves from Dietfurt (left) and images of the feeding vessels found in each grave (right). Photographs of vessels were taken by A.F. (a) and K.R.-S. (b). Drawings of the graves were reproduced from a previously published plan17 (a) and drawing18 (b).

In the labs where I work, we analyze fatty acids by LC/MS/MS which is generally more sensitive than GC-MS single quads with derivatization to FAMES (fatty acid methyl esters), but the authors here have used the latter, and apparently it got the job done, utilizing the NIST databases. (I'd personally be reluctant to do this with samples this precious, but it worked out apparently; the paper is published in Nature.)

Their results:



The caption:

n = 3 vessels. a–c, Partial gas chromatograms of transmethylated trimethylsilylated extracts from infant-feeding vessels 1–3. Red circles, n-alkanoic acids (fatty acids); blue triangles, n-alkanes; IS, internal standard, C34 n-tetratriacontane. d, ?13C values for the C16:0 and C18:0 fatty acids for archaeological fats extracted from infant-feeding vessels 1–3. The three fields correspond to the P = 0.684 confidence ellipses for animals raised on a strict C3 diet in Britain20. Each data point represents an individual vessel. e, The ?13C (?13C18:0 – ?13C16:0) values are from the same vessels as in d. The ranges shown here represent the mean ± 1 s.d. of the ?13C values from a global database comprising modern reference animal fats, which have been published previously24. f, Partial high-temperature gas chromatogram of trimethylsilylated total lipid extract of infant-feeding vessel 2, showing degraded animal fat. Red circles indicate short- and long-chain n-alkanoic acids with the indicated number of carbon atoms; monoacylglycerols (M) containing 16 and 18 acyl carbon atoms; diacylglycerols (D) containing 28, 30, 32 and 34 acyl carbon atoms; triacylglycerols (T), containing 40, 42, 44, 46, 48, 50, 52 and 54 acyl carbon atoms; the plasticizer is indicated by an asterisk. IS, internal standard n-tetratriacontane (n-C34). Replication was not possible owing to the unique and irreplaceable nature of the archaeological artefacts sampled, although the objects were analysed using two different extraction methods.

Here's some explanation of the different lipid profiles of cow's milk and human milk:

As the ?13C values are found to be at the top of the range for dairy fats, the vessels were also analysed by solvent extraction20 using high-temperature gas chromatography and high-temperature gas chromatography–mass spectrometry for diagnostic intact acyl lipids22. Figure 2f shows that triacylglycerols (TAGs) and their degradation products, di- and monoacylglycerols, were present in vessel 2, with TAGs comprising C40–C54 acyl carbon atoms with C48 being the most abundant homologue. The latter TAGs were not detectable in vessels 1 and 3, indicating complete diagenetic hydrolysis of the acyl lipids in these vessels. Fresh adipose fats are characterized by TAGs that contain 48–54 acyl carbon atoms, whereas dairy fats are distinguished by TAGs that contain 24–54 acyl carbon atoms23. Whereas shorter-chain TAGs (24–38 acyl carbon atoms) are rarely seen in degraded archaeological fats, owing to diagenetic loss (which has been demonstrated experimentally20), C40–C46 TAGs are highly diagnostic of dairy fats20,22. In summary, our findings provide unequivocal evidence that all three vessels were predominantly used to process dairy fats.

Nutritional differences:

Milks are species-specific and there are key differences in the composition of human and ruminant milk. Animal milk could have been used as a supplementary food, but it would not have been a full replacement for human milk, which contains similar amounts of lipid but more carbohydrates (in the form of lactose) and considerably less protein. These differences might affect an infant in various ways. For instance, cow’s milk is more difficult for an infant to absorb as it contains higher quantities of saturated fatty acids and much larger fat globules than human milk25, causing a reduced energetic input for the infant. The processing of animal milk and the possible incorporation of meat-based gruel may have served to balance out nutritional deficiencies. However, the introduction of inappropriate supplementary foods would have provided an opportunity for infectious agents and pathogens, causing diarrhoea and other diseases, and putting the infant at greater risk of iron-deficiency anaemia14. These supplementary foods may also have been nutritionally inadequate, leading to malnutrition, which is detrimental to future development.

My sons were both with me this weekend, and we had this fascinating conversation on why European culture came to be so widely adopted across the world, which of course, is tied to imperialism, the latter being tied to a cultural propensity for violence that was not absent in other cultures, but seems to have been less intense, the Mongols, perhaps excepted. I mentioned Kurt Vonnegut's description of Europeans as "sea pirates" which other cultures refused to believe could possibly be as greedy and violent as they turned out to be. My younger son had an interesting theory related to geography to explain the warlike practices of Europeans. We were just kicking stuff around. I don't know that we were being cartoonish; I'm sure we were.

This may only be loosely tied to nutritional differences, but these nutritional differences have had an effect on culture.

It is well known for example, from genetic data, that Europeans as distinct from other ethic groups exhibit more tolerance for lactose than other ethic regions, which is why one never sees cheese sauce for example, in Chinese or Japanese food. It is also well known that, albeit, with many exceptions, that certain cancers are less prevalent in Asia, notably breast cancer.

Seemingly small things matter.

In any case, I found this interesting chemoarcheology to be very interesting, and I thought I'd share it.

Have a nice day tomorrow.