Subsistence patterns in West Central Africa during the ‘Stone to Metal Age’ transition phase: stable isotope analysis of human remains from the site of Shum Laka (North-West Cameroon )

The ‘Stone to Metal Age’ transition phase leading to subsistence shifts and iron production is still poorly understood in West Central Africa . In order to elucidate these phenomena in the Grassfields, a key-region in Cameroon possibly related to the expansion of Bantu-speaking populations, samples of ancient human and animal remains were selected for carbon and nitrogen isotope analysis. Our results indicate that the food resources consumed by the inhabitants of Shum Laka originated essentially from C3 plants, either directly in the form of C3 tuber roots such as wild manioc, or indirectly through the consumption of C3 eaters such as wild species of suidae and possibly chimpanzee, although the consumption of savanna buffalo cannot be excluded. The trophic position of the ancient humans is better estimated by the δ15N values, and indicates that their protein source was primarily from herbivore meat. Therefore, all data seem to agree with both, the environmental context (forest/savana transition area) and more specifically, the hunter-gatherer subsistence strategy based mainly on resources found in light forest undergrowth. Although dietary variations (protein content, types of plants consumed) will be further explored in relation to both chronological phase and age-at-death, preliminary results (higher δ15N values below 2-4 years) suggest weaning process occurring in youngest individuals.