Study Notes on Human Footprints and Ecology in the Arabian Interior

Human Footprints Provide Snapshot of Last Interglacial Ecology in the Arabian Interior

Authors:

  • Mathew Stewart, Richard Clark-Wilson, Paul S. Breeze, Klint Janulis, Ian Candy, Simon J. Armitage, David B. Ryves, Julien Louys, Mathieu Duval, Gilbert J. Price, Patrick Cuthbertson, Marco A. Bernal, Nick A. Drake, Abdullah M. Alsharekh, Badr Zahrani, Abdulaziz Al-Omari, Patrick Roberts, Huw S. Groucutt, Michael D. Petraglia

Introduction

  • Context: The nature of human dispersals out of Africa has been elusive due to poor paleoecological data associated with early non-African humans.

  • Findings: The report contains hominin and non-hominin mammalian tracks from an ancient lake deposit in the Arabian Peninsula, dating to the last interglacial.

    • This may represent the oldest securely dated evidence for Homo sapiens in Arabia.

    • Indicates a well-watered semi-arid grassland during human movements into the Nefud Desert of Saudi Arabia.

    • Lake visitation by late Pleistocene humans and animals was likely transient, mainly for drinking and foraging needs.

Geographical Significance

  • Southwest Asia: The biogeographical gateway between Africa and Eurasia, crucial for understanding hominin and fauna dispersal.

    • First Homo sapiens fossils recorded outside Africa around 210,000 to 180,000 years ago in Greece and the Levant respectively.

    • Evidence of human arrival in the Arabian interior by at least 85,000 years ago.

  • Alathar Lacustrine Deposit: Site in western Nefud Desert providing fossil and footprint evidence.

Footprints and Fossils Found

  • Footprint Details: Total of 376 footprints recorded with 177 able to be classified into an ichnotaxon.

    • 7 hominin footprints identified, suggesting responsible tracks belong to Homo sapiens based on fossils and archaeological evidence.

    • Human footprints (HPR001 to HPR004) suggest non-directional activities at the lake, possibly two to three individuals moving together.

  • Animal Tracks and Fossils: Various large mammals attracted to the lake, including elephants, camels, and bovid remains.

    • Tracks indicated movements towards diminishing water supplies during a dry season.

    • Elephant tracks (n = 43) and camel tracks (n = 107) indicate congregation patterns reflecting seasonality and resource availability.

Geological and Chronological Analysis

  • Sediment Analysis:

    • The Alathar deposit indicates an inverted relief feature with a sedimentary sequence comprising a 1.8m-thick sandy-silt diatomite.

    • Optically stimulated luminescence (OSL) dating of samples below and above the footprint-bearing unit gave ages of 121 ± 11 ka and 112 ± 10 ka, effectively dating the prints.

Diatom Paleoecology

  • The lake was an oligotrophic, nutrient-poor freshwater lake, consistent with other similar deposits, indicating a vital habitat for fauna.

  • The presence of these freshwater lakes provided critical resources for human and animal populations.

Observations and Interpretations

  • **Human and Animal Interactions:

    • Hominin foot traffic suggests that humans visited the lake transiently, primarily for water, as evidenced by the lack of butchery marks and stone tools.

  • Animal Behavior:

    • Elephants' movement patterns suggest Atlantic water resources aligned with seasonal rainfall changes. Presence linked to herbivores congregating around the water sources, making it a notable habitat for hominins.

Fossil Evidence

  • 233 fossils recovered, including remains of Oryx and elephants.

  • Taphonomic histories of fossils suggest complex interactions tied to seasonal migrations and resource availability.

  • Carbon isotope analysis indicates significant consumption of C4 grasses, corroborating habitat types found in modern-day savanna ecosystems.

Conclusion

  • The findings reveal a direct spatial and temporal link between late Pleistocene humans and large herbivores in Arabia.

  • Suggest transient lakeshore visits tied to water resource needs during dry periods.

    • Hominin movements in Arabia were part of larger migratory and environmental patterns.

Materials and Methods

Sedimentology and Diatom Analysis

  • Sediment samples collected for laboratory analysis using X-ray diffraction and thin section preparation.

OSL and U-series Dating

  • Methods outlined for luminescence dating including sampling, sediment analysis, and dose calculations.

Footprint Morphometric Data Analysis

  • Footprint dimensions analyzed using scaled photographic documentation and software aids.

Stable Isotope Analysis

  • Carbon and oxygen isotope analysis conducted on recovered fossil Bovid and elephant teeth to reconstruct dietary habits and environmental conditions.

References

  • Cited numerous studies regarding human dispersal, paleoecology, and isotopic analysis relevant to the context of ancient hominins and their habitats.