Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Ancient herders enriched and restructured African grasslands

Abstract

Grasslands are one of the world’s most extensive terrestrial biomes and are central to the survival of herders, their livestock and diverse communities of large wild mammals1,2,3. In Africa, tropical soils are predominantly nutrient-limited4,5,6 but productive grassy patches in wooded grassland savannah ecosystems2,4 grow on fertile soils created by geologic and edaphic factors, megafauna, fire and termites4,5,6. Mobile pastoralists also create soil-fertility hotspots by penning their herds at night, which concentrates excrement—and thus nutrients—from grazing of the surrounding savannahs7,8,9,10,11. Historical anthropogenic hotspots produce high-quality forage, attract wildlife and increase spatial heterogeneity in African savannahs4,12,13,14,15. Archaeological research suggests this effect extends back at least 1,000 years16,17,18,19 but little is known about nutrient persistence at millennial scales. Here we use chemical, isotopic and sedimentary analyses to show high nutrient and 15N enrichment in on-site degraded dung deposits relative to off-site soils at five Pastoral Neolithic20 sites (radiocarbon dated to between 3,700 and 1,550 calibrated years before present (cal. bp)). This study demonstrates the longevity of nutrient hotspots and the long-term legacy of ancient herders, whose settlements enriched and diversified African savannah landscapes over three millennia.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Study areas and sampled sites.
Fig. 2: Elemental nitrogen and phosphorous concentrations in sediment from on- and off-site stratigraphic sections.
Fig. 3: δ13C and δ15N values measured in on-site and off-site sediment samples from five archaeological sites in East Africa.

References

  1. Reynolds, S. G. in Grasslands of the World (eds Suttle, J. M. et al.) 1–17 (Food and Agriculture Organization of the United Nations, Rome, 2005).

  2. Sankaran, M. et al. Determinants of woody cover in African savannas. Nature 438, 846–849 (2005).

    CAS  Google Scholar 

  3. Reid, R. S. Savannas of our Birth (Univ. California Press, Berkeley, 2012).

  4. Scholes, R. J. & Walker, B. H. An African Savanna. Synthesis of the Nylsvley study (Cambridge Univ. Press, Cambridge, 1993).

    Google Scholar 

  5. Bell, R. H. V. in Ecology of Tropical Savannas (eds Huntley, B. J. & Walker, B. H.) 193–216 (Springer, Berlin, 1982).

  6. Cech, P., Kuster, T., Edwards, P. J. & Venterink, H. O. Effects of herbivory, fire and N2-fixation on nutrient limitation in a humid African savanna. Ecosystems 11, 991–1004 (2008).

    CAS  Google Scholar 

  7. Augustine, D. J., McNaughton, S. J. & Frank, D. A. Feedbacks between soil nutrients and large herbivores in a managed savanna ecosystem. Ecol. Appl. 13, 1325–1337 (2003).

    Google Scholar 

  8. Porensky, L. M. & Veblen, K. E. Generation of ecosystem hotspots using short-term cattle corrals in an African savanna. Rangeland Ecol. Manag. 68, 131–141 (2015).

    Google Scholar 

  9. Shahack-Gross, R., Marshall, F. & Weiner, S. Geo-ethnoarchaeology of pastoral sites: the identification of livestock enclosures in abandoned Maasai settlements. J. Archaeol. Sci. 30, 439–459 (2003).

    Google Scholar 

  10. Turner, M. Long term effects of daily grazing orbits on nutrient availability in Sahelian West Africa: I. Gradients in the chemical composition of rangeland soils and vegetation. J. Biogeogr. 25, 669–682 (1998).

    Google Scholar 

  11. Georgiadis, N. J. & McNaughton, S. J. Elemental and fibre contents of savanna grasses: variation with grazing, soil type, season and species. J. Appl. Ecol. 27, 623–634 (1990).

    CAS  Google Scholar 

  12. Muchiru, A. N., Western, D. J. & Reid, R. S. The impact of abandoned pastoral settlements on plant and nutrient succession in an African savanna ecosystem. J. Arid Environ. 73, 322–331 (2009).

    Google Scholar 

  13. van der Waal, C. et al. Large herbivores may alter vegetation structure of semi-arid savannas through soil nutrient mediation. Oecologia 165, 1095–1107 (2011).

    Google Scholar 

  14. Muchiru, A. N., Western, D. J. & Reid, R. S. The role of abandoned pastoral settlements in the dynamics of African large herbivore communities. J. Arid Environ. 72, 940–952 (2008).

    Google Scholar 

  15. Porensky, L. M. & Veblen, K. E. Grasses and browsers reinforce landscape heterogeneity by excluding trees from ecosystem hotspots. Oecologia 168, 749–759 (2012).

    Google Scholar 

  16. Denbow, J. R. Cenchrus ciliaris: an ecological indicator of Iron Age middens using aerial photography in eastern Botswana. S. Afr. J. Sci. 75, 405–408 (1979).

    Google Scholar 

  17. Huffman, T. N., Elberg, M. & Watkeys, M. Vitrified cattle dung in the Iron Age of southern Africa. J. Archaeol. Sci. 40, 3553–3560 (2013).

    CAS  Google Scholar 

  18. Shahack-Gross, R., Simons, A. & Ambrose, S. H. Identification of pastoral sites using stable nitrogen and carbon isotopes from bulk sediment samples: a case study in modern and archaeological pastoral settlements in Kenya. J. Archaeol. Sci. 35, 983–990 (2008).

    Google Scholar 

  19. Boles, O. J. C. & Lane, P. The green, green grass of home: an archaeo-ecological approach to pastoralist settlement in central Kenya. Azania 51, 507–530 (2016).

    Google Scholar 

  20. Ambrose, S. H. in Encyclopedia of Prehistory, Vol. 1, Africa (eds Peregrine, P. N. & Ember, M.) 97–109 (Kluwer/Plenum, New York, 2001).

  21. Frank, D. A., Evans, R. D. & Tracy, B. F. The role of ammonia volatilization in controlling the natural 15N abundance of a grazed grassland. Biogeochemistry 68, 169–178 (2004).

    CAS  Google Scholar 

  22. Macharia, A. N., Uno, K. T., Cerling, T. E. & Brown, F. H. Isotopically distinct modern carbonates in abandoned livestock corrals in northern Kenya. J. Archaeol. Sci. 39, 2198–2205 (2012).

    Google Scholar 

  23. Ambrose, S. H. Effects of diet, climate and physiology on nitrogen isotope abundances in terrestrial foodwebs. J. Archaeol. Sci. 18, 293–317 (1991).

    Google Scholar 

  24. Shahack-Gross, R. Herbivorous livestock dung: formation, taphonomy, methods for identification, and archaeological significance. J. Archaeol. Sci. 38, 205–218 (2011).

    Google Scholar 

  25. Shahack-Gross, R., Berna, F., Karkanas, P. & Weiner, S. Bat guano and preservation of archaeological remains in cave sites. J. Archaeol. Sci. 31, 1259–1272 (2004).

    Google Scholar 

  26. Lane, P. An outline of the later Holocene archaeology and precolonial history of the Ewaso Basin, Kenya. Smithson. Contrib. Zool. 632, 11–30 (2011).

    Google Scholar 

  27. Lamprey, R. H. & Reid, R. S. Expansion of human settlement in Kenya’s Maasai Mara: what future for pastoralism and wildlife? J. Biogeogr. 31, 997–1032 (2004).

    Google Scholar 

  28. Western, D. & Dunn, T. Environmental aspects of settlement site decisions among pastoral Maasai. Hum. Ecol. 7, 75–98 (1979).

    Google Scholar 

  29. Robertshaw, P., Pilgram, T., Siiriainen, A. & Marshall, F. in Early Pastoralists of Southwestern Kenya (ed. Robertshaw, P.) 36–51 (British Institute in Eastern Africa, Nairobi, 1990).

  30. Shahack-Gross, R. & Finkelstein, I. Subsistence practices in an arid environment: a geoarchaeological investigation in an Iron Age site, the Negev Highlands, Israel. J. Archaeol. Sci. 35, 965–982 (2008).

    Google Scholar 

  31. Frachetti, M. D. Pastoralist Landscapes and Social Interaction in Bronze Age Eurasia (Univ. of California Press, Berkeley, 2008).

    Google Scholar 

  32. Bruno, M. C. & Hastorf, C. A. in An Archaeology of Andean Pastoralism (eds Capriles, J. M. & Tripcevich, N.) 55–65 (Univ. New Mexico Press, Albuquerque, 2016).

  33. Wickham, H. ggplot2: Elegant Graphics for Data (Springer, New York, 2009).

    Google Scholar 

  34. Bronk Ramsey, C. Bayesian analysis of radiocarbon dates. Radiocarbon 51, 227–260 (2009).

    Google Scholar 

  35. Hogg, A. G. et al. SHCal13 Southern Hemisphere calibration, 0–50,000 years cal. bp. Radiocarbon 55, 1889–1903 (2013).

    CAS  Google Scholar 

  36. Simons, A. The Development of Early Pastoral Societies in South-Western Kenya: A Study of the Faunal Assemblage from Sugenya and Oldorotua 1. PhD thesis, La Trobe Univ. (2004).

  37. Nelson, C. M. & Kimengich, J. in Origin and Early Development of Food-Producing Cultures in Northeast Africa (ed. Krzyzaniak, L.) 481–487 (Polish Academy of Sciences, Poznan, 1984).

  38. Bower, J. R. F., Nelson, C. M., Waibel, A. F. & Wandibba, S. The University of Massachusetts’ Later Stone Age/Pastoral Neolithic comparative study in central Kenya: an overview. Azania 12, 119–146 (1977).

    Google Scholar 

Download references

Acknowledgements

We thank the Kenya Ministry of Science and Technology for permission to conduct research (MOST 13/001/38C234, NCST RRI/12/BS011/38) and National Museums of Kenya for research affiliation, excavation licence and support. We are grateful to J. K. Mulwa and M. Mulwa, for site access at Lukenya and to A. Kabiru, J. M. Munyiri, N. Ole Simpai, H. Ole Saitabau and J. K. Ole Tumpuya for research assistance. Funding was received from Washington University in St Louis I-CARES and support from the Liu and the Kidder laboratories, the Nano Research Facility at Washington University, NSF Grant No. ECS-0335765 and the University of Illinois Environmental Isotope Paleobiogeochemistry Laboratory.

Reviewer information

Nature thanks N. Boivin, R. Conant, J. Lee-Thorp and the other anonymous reviewer(s) for their contribution to the peer review of this work.

Author information

Authors and Affiliations

Authors

Contributions

F.M. and S.H.A. designed the study; F.M., S.H.A., A.W. and S.G. collected field data, R.E.B.R., R.S.-G., S.G., M.S., S.A. and L.H. performed analyses. All authors discussed data and wrote the paper.

Corresponding authors

Correspondence to Fiona Marshall or Stanley H. Ambrose.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data figures and tables

Extended Data Fig. 1 On-site versus off-site sediment profiles for sampled locales.

a, On-site and off-site stratigraphy at Indapi Dapo. a1 depicts on-site stratigraphy: (1) modern topsoil, (2) light grey cultural horizon, (3) light yellow–brown cultural and dung horizon, (4) discontinuous harder trampled surface and (5) dark yellow–brown sterile sediments. a2 depicts off-site stratigraphy: (1) loamy modern topsoil, (2) brown silts with carbonate nodules and (3) rocky bedrock-derived sediment. b, On-site and off-site stratigraphy at Oloika 1. b1 depicts on-site stratigraphy: (1) modern topsoil, (2) pale grey cultural and dung horizon, (3) compacted cultural horizon with hard undulating calcium carbonate crust and (4) sterile oxidized palaeosol with manganese nodules. b2 depicts off-site stratigraphy: (1) light brown modern topsoil, (2) grey–brown sediment with carbonate nodules, (3) oxidized subsoil. c, On-site and off-site stratigraphy at Oloika 2. c1 depicts on-site stratigraphy: (1) modern topsoil, (2) pale grey cultural and dung horizon, (3) compacted calcium carbonate lens, (4) oxidized subsoil, (5) recent animal burrow and (6) oxidized subsoil pisolithic formation with manganese nodules. c2 depicts off-site stratigraphy: (1) light brown modern topsoil, (2) grey–brown sediment with carbonate nodules and (3) consolidated lighter grey soil with increasing carbonate nodules. d, On-site road-cut (GvJm48) and step-trench (GvJm44) stratigraphy, and off-site stratigraphy at GvJm44. d1 depicts the GvJm48 road-cut stratigraphy: (1) modern topsoil, (2) grey–brown silty loam, (3a, 3b, 3c) top, middle and bottom, respectively, of pale grey silty loam cultural and dung horizon, (4) pre-cultural loam palaeosol and (5) bedrock-derived weathered sediments. d2 depicts the GvJm44 step-trench stratigraphy: (1) modern topsoil, (2) dark yellow–brown clay grading to silty loam cultural horizon and (3) lower dark brown silty loam cultural horizon. d3 depicts off-site stratigraphy at GvJm44: (1) modern topsoil, (2) dark brown to red brown sandy loam (3) sandy loam.

Extended Data Fig. 2 Archaeological landscapes and stratigraphic sections.

a, Satellite image of GvJm44 and GvJm48, Lukenya (dry season). At GvJm48, a track exposes fine-grained grey midden deposits in an open grassy area. Redder sandy clays are exposed north and south of the site. b, Landscape and stratigraphic view of GvJm44, showing dark Neolithic midden sediment in cross section. Arrows indicate midden edges. Person standing atop the centre of the midden is about 165-cm tall. c, Dung layer at GvJm48. d, Open glades visible near the Ntuka River (dry season) at Ol Owarukeri (GvJh108), a large Elmenteitan (Pastoral Neolithic tradition dating to approximately 3,500–1,500 cal. bp) site with modern pastoralist settlement and two smaller Pastoral Neolithic sites, one with modern settlement. a, d, Imagery from Google Earth Pro, Digital Globe. b, c, Photographs by S.H.A., 1977–1978.

Extended Data Fig. 3 Sediment sample micromorphology.

a, Flatbed scan of a thin section representing off-site sediments (Oloika 1). b, Flatbed scan of a thin section representing on-site sediments (Oloika 1). Both scans are 6.2-cm wide. Note the colour and structure differences between on-site and off-site sediments. The reddish rounded particles are weathered local magmatic rock. c, Microphotograph of on-site sediments (Indapi Dapo) showing granular microstructure associated with large voids, which indicates severe bioturbation. Note the modern plant root (1) within the large void on the right. Scale bar, 1 mm; plane-polarized light. d, Microphotograph of on-site sediments (Indapi Dapo) showing black manganese-oxide florets (2), which indicate periods of water saturation. Scale bar, 1 mm; plane-polarized light. e, Microphotograph of on-site sediments (Oloika 2) that have been disaggregated (‘grain mount’) to enable clear observation of phytoliths and dung spherulites. Arrows point to several phytoliths of various types. Scale bar, 0.1 mm; plane-polarized light. f, Same view as in e, but in crossed-polarized light. Arrows point to a few dung spherulites.

Extended Data Fig. 4 Ternary plot of particle size distributions for sampled archaeological and off-site contexts.

n = 8 archaeological contexts; n = 8 off-site contexts. See Supplementary Table 1 for values. Plot generated using the ggtern extension for ggplot233.

Extended Data Fig. 5 Landscape of Nkuta showing 116 modern and 5 ancient pastoral settlements (bomas) visible in the study area.

Ole Pariata (1), Ol Owarukeri (GvJh108) (2), Oloika 1 (3), Oloika 2 (4) and Indapi Dapo (5). ArcGIS model with a base 30-m-resolution digital elevation derived from the Shuttle Radar Topography Mission.

Extended Data Table 1 Archaeology
Extended Data Table 2 Radiocarbon dates

Supplementary information

Supplementary Information

This file contains Supplementary Notes Parts A-H and Supplementary References.

Life Sciences Reporting Summary

Supplementary Table 1

Particle size, loss on ignition, magnetic susceptibility, ICPMS elemental, isotope, and FTIR data for on- and off-site sediment samples.

Supplementary Table 2

Summary of data from African anthropogenic hotspots.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Marshall, F., Reid, R.E.B., Goldstein, S. et al. Ancient herders enriched and restructured African grasslands. Nature 561, 387–390 (2018). https://doi.org/10.1038/s41586-018-0456-9

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/s41586-018-0456-9

Keywords

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing