Isotopic study suggests men and women had equal access to resources 6,000 years ago

Thanks to isotope geochemistry, a team from the University of Geneva (UNIGE) discovered new information about the Barmaz necropolis in Valais (Switzerland): 14% of the people buried on this site 6000 years ago were not Locals. Furthermore, the study suggests that this Middle Neolithic agropastoral society, one of the oldest known in French-speaking Switzerland, was relatively egalitarian.

Isotopic ratios of carbon, nitrogen, and sulfur in the bones reveal that all members of the community, including people who came from elsewhere, had access to the same food resources. These results are published in the Journal of Archaeological Sciences: Reports.

The Neolithic era marks the beginning of livestock breeding and agriculture. In Switzerland, this period extends between 5500 and 2200 BC. Early agropastoral communities gradually moved from a predatory economy – in which hunting and gathering provided the nutrients essential to their survival – to a production economy.

This radically changed the eating habits and functioning dynamics of Neolithic populations. The bones and teeth of individuals retain chemical traces that scientists are now able to detect and interpret.

The objective of the study carried out by Déborah Rosselet-Christ, doctoral student at the Laboratory of African Archeology and Anthropology of the Faculty of Sciences of UNIGE, is to apply isotopic analysis to human remains. dating from the Neolithic to learn more about their diet and mobility.

The levels of certain isotopes of carbon, nitrogen, sulfur and strontium depend on the environment in which each individual lives and feeds. Isotopes are atoms that have the same number of electrons and protons but different numbers of neutrons. This very precise and delicate technique is applied for the first time to alpine agropastoral populations from the Middle Neolithic of western Switzerland.

Mobility according to the second molar

Excavated in the 1950s and 1990s, the Barmaz site in Collombey-Muraz, in the Valais Chablais, is one of the oldest vestiges of agropastoral societies in French-speaking Switzerland to have preserved human remains. It includes two necropolises containing the bones of approximately seventy individuals. For her master’s degree, Déborah Rosselet-Christ, the first author of the study, selected 49 (as many women as men) from whom she systematically took samples of collagen from certain bones, as well as fragments of enamel of their second molars.

“The second molar is a tooth whose crown forms between three and eight years of age,” explains the researcher.

“Once formed, dental enamel is not renewed for the rest of its life. Its chemical composition therefore reflects the environment in which its owner lived during his childhood. Strontium (Sr) is a good marker of mobility. The abundance ratio between two of its Isotopes, that is to say their proportion, varies greatly depending on the age of the surrounding rocks. These chemical elements are found in the enamel via the food chain, leaving a. indelible signature specific to each environment.

Analysis of strontium isotope ratios in the 49 individuals from Barmaz reveals a high degree of homogeneity in most of them and markedly different values ​​in only 14% of the samples, indicating a different origin.

“The technique makes it possible to determine that these are individuals who did not live the first years of their life in the place where they were buried, but it is more difficult to determine where they came from” , specifies Jocelyne Desideri, lecturer at the Laboratory of African Archeology and Anthropology of the Faculty of Sciences of UNIGE, last author of the article.

“Our results show that people were on the move at this time. This is not surprising since several studies have highlighted the same phenomenon in other places and at other times during the Neolithic period.”

Diet recorded in collagen

Collagen is used to determine the isotope ratios of carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S). Each measurement provides information on specific aspects of the diet, such as categories of plants according to the type of photosynthesis they use, the quantity of animal proteins or even the contribution of aquatic animals.

Since bones are constantly renewing themselves, the results only concern the last years of an individual’s life. That said, scientists were able to deduce that these ancient inhabitants of the Barmaz region had a diet based on terrestrial (and not aquatic) resources, with a very high consumption of animal proteins.

“What is more interesting is that we measured no difference between men and women,” notes Déborah Rosselet-Christ.

“Nor even between locals and non-locals. These results therefore suggest equality of access to food resources between the different members of the group, regardless of their origin or gender. However, this is not always the case. It exists for example dietary differences between the sexes in the Neolithic populations of southern France.

A clearer image of agropastoral societies

However, scientists were able to show that non-local populations were only buried in one of the necropolises (Barmaz I) and that higher levels of the nitrogen isotope were measured in the other (Barmaz II). . Given that the two necropolises were contemporaneous (and only 150 meters apart), this latter observation raises the question of whether there was a difference in social status between the two groups of deceased.

“Our isotopic measurements constitute an interesting complement to other approaches used in archaeology,” explains Jocelyne Desideri. “They help to clarify the picture that we are trying to paint of the life of these first Alpine agropastoral societies, of the relationships between individuals and their mobility.”

Déborah Rosselet-Christ is currently continuing this work as part of her doctoral thesis, co-directed by Jocelyne Desideri and Massimo Chiaradia (lecturer, Department of Earth Sciences).

Alongside a multidisciplinary team specializing in genetics, paleopathology, dental calculus and morphology, she is broadening her field of study by including other sites in Valais and Val d’Aosta in Italy, covering a wider Neolithic period and using other isotopes, such as neodymium, potentially interesting in a prehistoric archaeological context.