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Herbivore Tooth Enamel Points to Repeated Ecological Stability Along the Lebanese Coast

Male Persian fallow deer standing in Mediterranean woodland at Mount Carmel Nature Preserve
Research · Ecology

Stable isotopes preserved in fossil herbivore teeth indicate that relatively moist, productive environments repeatedly occurred along the Lebanese coast during widely separated parts of the Pleistocene. The study analysed 58 teeth from eight herbivore taxa at Naame, Nahr Ibrahim and Ras el-Kelb, with the main assemblages spanning roughly 400,000 to 100,000 years ago. Despite major climatic oscillations across the wider eastern Mediterranean, the sampled intervals repeatedly recorded C3-dominated vegetation, reliable water availability and broadly regular Mediterranean seasonality.

The authors interpret this recurrence as evidence that the Lebanese coastal zone acted as a persistent or recurrent ecological refugium. Reliable vegetation, water and herbivore prey could have supported hominins occupying or moving through the region, but the study did not directly test human population movements.

Tooth enamel recorded diet, water and seasonality

The researchers measured carbon and oxygen isotope ratios in 30 bulk enamel samples and 295 sequential bands taken along growing teeth. Carbon isotopes reflect the plants an animal ate and therefore help reconstruct vegetation structure. Oxygen isotopes are influenced by drinking water and seasonal climate. Sequential samples can preserve changes over part of an animal’s life rather than only a single average value. Preservation checks were used to remove altered material before the environmental reconstruction.

C3 vegetation supported different feeding niches

All reconstructed dietary carbon-isotope values were consistent with C3 plants — the photosynthetic group that includes trees, shrubs and most temperate vegetation — rather than landscapes dominated by warm-climate C4 grasses. The isotope ranges point to woodland, scrub and other relatively mesic habitats, with Naame showing the broadest mixture of more closed and more open vegetation.

The herbivores nevertheless used those landscapes differently. Persian fallow deer, red deer and wild goat often showed isotope patterns consistent with shaded understory resources, whereas aurochs, rhinoceros and equids were associated more strongly with open or mixed feeding environments. In wild goats and Persian fallow deer, paired carbon and oxygen profiles also suggest greater use of shaded or moisture-buffered habitats during warmer parts of the year. These are interpretations of isotope patterns rather than direct observations of seasonal habitat choice.

Regular Mediterranean seasonality recurred across the sampled intervals

Sequential oxygen-isotope profiles generally followed regular cycles consistent with cool, wet winters and warm, dry summers. Ras el-Kelb showed smaller seasonal amplitudes than Naame and Nahr Ibrahim and was interpreted as somewhat cooler and less strongly seasonal.

One much younger aurochs tooth from Naame, dating to the last glacial period, recorded markedly colder and drier conditions than the older Naame material. Because this result comes from one animal, the authors treat it cautiously. It is also an important reminder that the coast was not environmentally stable during every climatic phase.

Repeated stability does not mean an unchanging 300,000-year record

The authors propose that the nearby Mediterranean, rainfall generated as moist air rose over the mountains and steep elevational gradients helped buffer the Lebanese coastal–mountain zone against some climatic extremes elsewhere in the region. In this interpretation, ecological stability means that productive, relatively moist C3 environments repeatedly reappeared in widely separated sampled intervals.

The reconstruction has clear limits. The teeth come from legacy collections excavated roughly 60–130 years ago, contextual records are incomplete, some material may be chronologically mixed or time-averaged, and several taxa are represented by very few teeth. The study documents three principal sampled intervals rather than an uninterrupted environmental history. Even with those caveats, coherent patterns within sites and across taxa support the authors’ conclusion that the Lebanese coast repeatedly provided a comparatively buffered ecological setting.

Sources and image credit

  1. Long-term ecological stability in the Pleistocene central Levantine corridor revealed by enamel isotopes from LebanonOpen-access primary research article in Communications Earth & Environment 7, 705 (2026). DOI: 10.1038/s43247-026-03925-x.

Image: Eyal Bartov — male Persian fallow deer (Dama mesopotamica) in Mount Carmel Nature Preserve, Israel, 17 August 2007; Wikimedia Commons; representative image of one of the herbivore taxa analysed in the study, not an animal from the archaeological assemblages. · CC BY-SA 3.0 — https://creativecommons.org/licenses/by-sa/3.0/ · Source

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