Hippos, today restricted to sub-Saharan Africa, survived in central Europe far longer than previously assumed. Analyses of bone finds demonstrate that hippos inhabited the Upper Rhine Graben sometime between approximately 47,000 and 31,000 years ago, well into the last ice age, as an international research team with the contribution of researchers from the University of Fribourg now reported.

Until now, it was believed that common hippos (Hippopotamus amphibius) became extinct in central Europe around 115,000 years ago, with the end of the last interglacial period. Together with colleagues from the University of Potsdam, the Reiss-Engelhorn-Museen Mannheim, the Curt-Engelhorn-Zentrum Archäometrie Mannheim, the ETH Zurich and other international partners, Andreas Füglistaler and Daniel Wegmann from the Department of Biology now demonstrated that hippos inhabited the Upper Rhine Graben in southwestern Germany sometime between approximately 47,000 and 31,000 years ago, i.e. during the middle of the last ice age.

The Upper Rhine Graben is an important continental climate archive. Animal bones that have survived for thousands of years in gravel and sand deposits are a valuable source for research. “It's amazing how well the bones have been preserved. At many skeletal remains it was possible to take samples suitable for analysis – that is not a given after such a long time,” emphasizes Dr. Ronny Friedrich, expert in age determination at the Curt-Engelhorn-Zentrum Archäometrie.

Hippos roamed along mammoth and wholly rhinos

The team radiocarbon dated numerous hippopotamus finds, which confirmed their presence during a milder climatic phase in the middle Weichselian glaciation. These results and further fossil evidence show that heat-loving hippos appeared in the same time frame as species adapted to cold temperatures, such as mammoths and woolly rhinos. “The results demonstrate that hippos did not vanish from middle Europe at the end of the last interglacial, as previously assumed,” summarizes first author Dr. Patrick Arnold. “Therefore, we should re-analyze other continental European hippo fossils traditionally attributed to the last interglacial period.”

A relict population of the common Hippo

The team additionally obtained ancient DNA data of several samples, which showed that European ice age hippos are closely related to African hippos living today and belong to the same species. Using dedicated bioinformatic tools developed by Andreas Füglistaler and Daniel Wegmann, the team was able to reliably conclude that the genetic diversity of these samples was very low, suggesting that the population in the Upper Rhine Graben was likely a small and isolated relict population of the common Hippos that had a much larger range in the past.

Prof. Dr. Wilfried Rosendahl, general director of the Reiss-Engelhorn-Museen Mannheim and project leader of “Eiszeitfenster Oberrheingraben” is convinced that ice age research still holds many exciting questions: “The current study proves that the ice age was not the same everywhere, but local peculiarities taken together form a complex overall picture – similar to a puzzle. It would now be interesting and important to further examine other heat-loving animal species, attributed so far to the last interglacial.”

Publication
Arnold, Patrick, et al. "Ancient DNA and dating evidence for the dispersal of hippos into central Europe during the last glacial." Current Biology (2025). https://doi.org/10.1016/j.cub.2025.09.035

Press release by the University of Potsdam
https://www.uni-potsdam.de/en/pressreleases/detail/2025-10-09-hippos-lived-in-europe-in-the-last-ice-age

Photo
Left mandible fragment of a female hippopotamus from Reiss-Engelhorn-Museen Mannheim, Slg. Reis Hippopotamus sp. Age dating: Between 46,000 and 48,300 years ago. Location: Bobenheim-Roxheim, Rhine-Palatinate district. Photo: Rebecca Kind