Ancient herders enriched and restructured African grasslands

Area of Science:

• Archaeology
• Soil Science
• Ecology

Background:

• Grasslands are vital biomes supporting pastoralists, livestock, and wildlife.
• African tropical soils are typically nutrient-poor, yet productive patches exist in savannahs.
• Mobile pastoralists create soil fertility hotspots through livestock management.

Observation:

• Historical human settlements are known to create nutrient hotspots.
• The persistence of these hotspots over millennial timescales is poorly understood.
• This study investigated nutrient persistence at five Pastoral Neolithic sites.

Findings:

• Chemical and isotopic analyses revealed significantly higher nutrient and 15N enrichment in on-site dung deposits compared to surrounding soils.
• These enriched deposits were found at Pastoral Neolithic sites dated between 3,700 and 1,550 calibrated years before present (cal. BP).
• The findings demonstrate the long-term persistence of nutrient hotspots created by ancient herders.

Implications:

• Ancient herders had a lasting impact on African savannah landscapes, enriching and diversifying them over millennia.
• These nutrient hotspots likely supported higher quality forage and attracted wildlife, increasing landscape heterogeneity.
• The study highlights the deep ecological legacy of pastoralism in shaping African environments.