Barmaz tomb chamblandes

Chamblandes tomb being excavated at the Barmaz site (Valais / Switzerland). Excavated by Marc-Rodolphe Sauter of the University of Geneva in the 1950s. © Université de Genève

GENEVA, Switzerland — Nestled in the heart of the Alps, the Valais region of Switzerland has a long and complex history of human settlement. Now, a new study is shedding light on the diet and mobility of some of the area’s earliest inhabitants – Neolithic agropastoral societies that called the region home over 5,000 years ago. By analyzing chemical traces in ancient bones, researchers have pieced together a fascinating picture of how these early farmers lived, ate, and moved across the landscape.

The study, led by Déborah Rosselet-Christ at the University of Geneva and published in the Journal of Archaeological Science: Reports, focused on human remains from two Middle Neolithic burial sites located just 200 meters apart in Collombey-Muraz, Switzerland. Known as Barmaz I and II, the necropolises date back to between 4500 and 3800 BCE and contain a total of 60 graves.

Using advanced techniques, the researchers measured the ratios of different isotopes of carbon, nitrogen, and sulfur in bone collagen, as well as strontium in tooth enamel. These chemical signatures can reveal clues about an individual’s diet and place of origin. Carbon and nitrogen isotopes, for instance, vary based on the types of plants and animals consumed, while strontium isotopes in teeth reflect the geology of the landscape where a person grew up.

The results paint an intriguing picture of life and death in Neolithic Valais. Individuals from both Barmaz I and II had a diet heavy in animal protein, likely from cattle, sheep, goats, and pigs. However, those buried at Barmaz II showed signs of having consumed a unique nitrogen-rich food source that was not part of the diet at Barmaz I. The researchers suggest this could be freshwater fish from nearby Lake Geneva and the Rhone River or meat from unweaned young animals.

Interestingly, while the two burial grounds are contemporaneous and close in proximity, they seem to tell different stories. Strontium analysis revealed that several individuals interred at Barmaz I spent their childhoods in a different geological region before moving to the area as adults. In contrast, everyone sampled from Barmaz II grew up locally. This suggests that the communities using the two necropolises, while living side-by-side, may have had distinct origins and social structures.

Barmaz archaeological site
Location of the Barmaz archaeological site. Computer graphics taken from the article Rosselet-Christ et al. 2024.

Paper Summary

Methodology

Understanding the findings with clarity requires a dip into the science. The researchers analyzed a total of 49 humans and 12 animal remains dated to the Middle Neolithic. From each human, they sampled bone fragments (mostly from the humerus) for dietary isotopes and dental enamel (primarily from second molars) for strontium. The human data was compared to isotopic values from local contemporary cattle, pigs, goats, and deer to establish an environmental baseline.

Dietary isotopes were measured through mass spectrometry on extracted bone collagen, an abundant protein that preserves well. The researchers looked at carbon-13 (δ13C), nitrogen-15 (δ15N), and sulphur-34 (δ34S). Strontium-87/86 ratios were measured on a Thermo-ionization Mass Spectrometer from dental enamel, which forms during childhood and reflects the geology of where an individual grew up.

Results

The human isotope data clustered in a way indicative of a primarily terrestrial, temperate C3-plant-based food web, consistent with early European farmers. The δ13C values were quite uniform, while δ15N and δ34S showed more variability.

When comparing the two burial sites, some striking differences emerged. Barmaz II individuals had significantly higher δ13C, δ15N, and δ34S values on average than those from Barmaz I. This points to them either having greater access to animal protein overall, or supplementing their diet with a distinctive 15N-enriched food source not consumed at Barmaz I.

The strontium results were even more telling. At Barmaz I, 7 of the 32 individuals (22%) had 87Sr/86Sr values outside the locally defined range, indicating they immigrated to the area after childhood. Remarkably, these non-locals were all adults; no Barmaz I children showed signs of being born elsewhere. In stark contrast, every individual tested from Barmaz II had local strontium signatures.

Limitations

As with any study of the ancient past, there are limitations to what can be said definitively. The researchers openly acknowledge the challenges of drawing broad conclusions from a single site and a relatively small sample size. For the dietary study especially, having a more robust isotopic baseline of local plants and animals from the period would allow for firmer interpretations.

Another inherent issue is that isotopes, while informative, do not give a full picture of ancient diets. They cannot distinguish between specific food sources with similar signatures, nor can they reveal the myriad of other factors – from food preparation to social norms – that shape how people eat. Integrating the isotopic findings with other archaeological evidence will be key to fleshing out the full story.

Takeaways

Limitations aside, this research offers valuable new insights into the lives of Switzerland’s earliest alpine farmers. It suggests that Neolithic communities, even those living in close proximity, could have distinct subsistence practices and mobility patterns.

The evidence that some people buried at Barmaz I grew up in a different region is particularly intriguing. It demonstrates that Neolithic populations were not necessarily static; some degree of mobility and migration was clearly part of life. However, the fact that the non-locals were exclusively adults raises further questions. Did they move to the area for marriage? Were they part of a special social class?

As for diet, the isotopic differences between the burial groups are subtle but meaningful. They hint at Barmaz II potentially having a special status or unique role that gave them access to different foods. The authors float the idea of Barmaz II engaging in specialized activities to explain both their distinct diet and the higher rate of healed injuries found in previous studies.

While much remains uncertain, this study demonstrates the power of isotopic analysis to reveal hidden aspects of prehistoric life. By unlocking the chemical echoes in ancient bones, archaeologists are slowly but surely piecing together the puzzle of how humans adapted to and thrived in the alpine landscape thousands of years ago. As the research continues, it promises to yield an ever-more detailed picture of Switzerland’s first farming communities.

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