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. 2026 Apr 6;21(4):e0345981.
doi: 10.1371/journal.pone.0345981. eCollection 2026.

Multiproxy stable isotope analysis provides insights into diet, animal management, and residential mobility in Old Bara, a metropolitan suburb of the Oyo Empire, West Africa

Moses Oluwaseyi Akogun  1   2 , Paul Szpak  2 , Vicky M Oelze  3 , Kendra Leishman  4 , Jay Hilsden  4 , Camilla Speller  4 , Lisa Janz  1 , Jonathan O Aleru  5 , Akinwumi Ogundiran  5   6
Affiliations

Multiproxy stable isotope analysis provides insights into diet, animal management, and residential mobility in Old Bara, a metropolitan suburb of the Oyo Empire, West Africa

Moses Oluwaseyi Akogun et al. PLoS One. .

Abstract

Old Bara was a royal suburb in the metropolis of the Oyo Empire, one of the most important political entities in Africa, ca. 1600-1835. Much of what is known about this town is limited to a few written and oral accounts about its functions as a royal cemetery where the priests and priestesses of the deified kings and other dependents also resided. These limited sources suggest that as a secluded site, Old Bara depended on the palace for its provisions. Archaeological, zooarchaeological, and bioarchaeological research at Old Bara has opened the opportunity to answer new questions about Old Bara's past and to evaluate its identity as a royal site. Here, we use carbon (δ13C), nitrogen (δ15N), sulfur (δ34S), and strontium (87Sr/86Sr) isotope analysis coupled with zooarchaeology and Zooarchaeology by Mass Spectrometry (ZooMS) to investigate animal provisioning, diet, and residential mobility in Old Bara. Our data provide evidence for local management of animal resources, including the first evidence for horse breeding in the Oyo Empire. The study also challenges the historical accounts that Old Bara was home primarily to palace retirees and priests and priestesses who were required to be celibate and relied on the palace for food provisions. The cumulative evidence from the analyses indicates that the royal town was part of the empire's animal resource production and distribution network.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Map of the extent of the Oyo Empire at its height ca.
1775 showing its capital (Oyo-Ile), some selected towns under the empires and vegetation zones. Map produced by Mech E. Frazier, Geographic Information System (GIS) Specialist, Northwestern University Libraries, specifically for this study (boundary and bathymetry data were sourced from Natural Earth [2025]).
Fig 2
Fig 2. Map of the metropolitan area of the Oyo Empire showing Oyo-Ile and Old Bara (the royal suburb).
Map provided by Akinwumi Ogundiran.
Fig 3
Fig 3. Map of Old Bara with its fortifications.
The five units with materials analyzed in this study are highlighted in red circle. Map provided by Macham Mangut.
Fig 4
Fig 4. Modelled dates from Individual 1 from S1002E5, Old Bara (Top: Combined dates using a Bayesian model in OxCal; Middle: Calibrated dates from Sample 296286; Bottom: Calibrated dates from Sample 296285).
Fig 5
Fig 5. Geological Map of Nigeria.
Map produced by Mech E. Frazier, Geographic Information System (GIS) Specialist, Northwestern University Libraries, specifically for this study (boundary data were sourced from Natural Earth [2025]; geological boundary data were sourced from the United States Geological Survey [2002]).
Fig 6
Fig 6. A – 87Sr/86Sr ratios from second upper molar of Individual 1 (Homo sapiens), B – dentinal collagen from Individual 1 showing the loci of sequential samples, C – 87Sr/86Sr ratios of snail shell (Limicolaria flammea) from Oyo-Ile (MJCV), D – 87Sr/86Sr ratios of snail shell (Limicolaria flammea) from Old Bara, E – 87Sr/86Sr ratios of cane rat (Thryonomys swinderianus) from Old Bara, F – horse (Equus caballus) tooth showing the multiple sampling loci, G – an upper dP3 from a foal (Equus caballus), H – lower molar of a donkey (Equus asinus), I – vertebrae of Nile perch (Lates niloticus), and J – femur of a Chicken (Gallus gallus domesticus) with dense medullary bone.
Fig 7
Fig 7. A convex hull showing the carbon (δ13C) and nitrogen (δ15N) isotope composition of faunal and human remains analyzed.
Fig 8
Fig 8. A convex hull showing carbon (δ13C) and sulfur (δ34S) isotope composition of faunal and human remains analyzed.
Note: The cow/bull from a coastal environment is highlighted in blue circle.
Fig 9
Fig 9. Probability map of the places of origin for Horses 1, 2, 3, 4, 6, and 7 based on the range of West African Dwarf horses, highlighting the study area (Old Bara and Oyo-Ile) and two other cavalry centres, Ede-Ile and Nupe (Raba).
Fig 10
Fig 10. Probability map of the places of origin for Horse 5 based on the range of West African Dwarf horses, highlighting the study area (Old Bara and Oyo-Ile) and two other cavalry centres, Ede-Ile and Nupe (Raba).
Fig 11
Fig 11. Summary of 87Sr/86Sr ratios for horses and donkeys.
The X-axis represents sequential samples from occlusal to enamel-root junction (black circles = cementum leachates, red triangles = soil leachates, magenta triangle = cane rat, and blue pentagon = snail shell).
Fig 12
Fig 12. Probability map of the places of origin for Donkey 1 and 2 based on the range of West African Dwarf horses, highlighting the study area (Old Bara and Oyo-Ile) and two other cavalry centres, Ede-Ile and Nupe (Raba).
Fig 13
Fig 13. Carbon (δ13C), nitrogen (δ15N), and sulfur (δ34S) isotope values of the tooth from Individual 1 with significant variation in δ13C and little variation in δ15N and δ34S.
See this image and copyright information in PMC

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