In my new paper published in Nature: Scientific Reports, I collaborated with archaeologists and scientists from the University of Haifa, the Geological Survey of Israel, the Israeli Antiquities Authority and the University of Connecticut. We analyzed faunal material from three archaeological sites in the Negev Desert, which were recently excavated by Guy Bar-Oz and his team on a European Research Council funded project “NEGEVGYZ: Crisis on the Margins of the Byzantine Empire.”
The aims of the overarching project were to tackle these long-standing conundrums:
1) Why did people build such large settlements (that housed thousands of inhabitants) in such an arid part of the southern Levantine region in the 4th century CE?
2) Why did these settlements collapse three centuries later?
In the past, historians and archaeologists have argued in favor of environmental factors or socio-political factors as a cause for the abandonment of the Byzantine settlements in the Negev. Many of these studies were related to long-term climatic trends, such as the speleothem record in the Soreq Cave. However, it was unclear what exactly what impact these long-term are regional-scale fluctuations were on the climate and rainfall patterns in the Negev Desert during periods of human occupation.
In this study, we used isotopic indicators of animal diets as a proxy to infer possible climatic shifts that may have led to the abandonment of the settlements of Shivta (Subeita), Nitzana (Nessana) and Halutza (Elusa). We took matching sequences of inorganic tooth enamel and organic tooth dentine from sheep and goat teeth dating to the Byzantine and Early Islamic periods from these sites. We measured stable carbon and oxygen isotopic values from the enamel and stable carbon and nitrogen isotopic values from the dentine.
The results provided insight into the composition of the animal diets during the wet winter season and the dry summer season. The oxygen isotopic values showed that the animals grazed at various locations around the desert, reflecting values of meteoric water ingested at different altitudinal regions of the surrounding landscape. The carbon isotopic values showed that the animals consumed a higher proportion of the more arid-adapted C4 plants in the wetter season. The nitrogen isotopic values showed that the animals spent both seasons in the dry Negev Desert, excluding the possibility that they migrated into the wetter regions to the north in the summer.
Overall, a lack of difference in the seasonal patterns, as well as the composition of the diet between the Byzantine and Early Islamic periods, indicates that no dramatic climatic downturn took place in the 7th century CE. This suggests that environmental change did not force the society to abandon these settlements. Instead, we propose that other reasons, including re-routing of trade routes through the desert or restructuring of the Empire’s territories was more likely to be the cause of the Byzantine collapse.