In a surprising revelation, new research indicates that hippos, typically associated with the warm climates of sub-Saharan Africa, managed to survive in central Europe far longer than previously believed. A comprehensive analysis of ancient bones has shown that these massive creatures lived in the Upper Rhine Graben between approximately 47,000 and 31,000 years ago, during the last ice age’s harshest periods. This groundbreaking study, conducted by an international team led by the University of Potsdam and the Reiss-Engelhorn-Museen Mannheim, was recently published in the journal Current Biology.
The announcement comes as a significant revision to the extinction timeline of the common hippopotamus (Hippopotamus amphibius) in Europe. Until now, scientists believed these animals disappeared from the region around 115,000 years ago, coinciding with the end of the last interglacial period. However, the new findings suggest that hippos persisted in the Upper Rhine Graben of southwestern Germany tens of thousands of years later, well into the middle of the last ice age.
Uncovering Ancient Climates
The Upper Rhine Graben is a critical site for understanding ancient climate conditions, with animal bones buried for millennia in layers of gravel and sand providing rare insights into the past. “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,” said Dr. Ronny Friedrich, a specialist in age determination at the Curt-Engelhorn-Zentrum Archäometrie.
Researchers employed genetic and radiocarbon dating methods to examine numerous hippopotamus fossils. Ancient DNA sequencing revealed that these Ice Age hippos were closely related to modern African populations, confirming they were part of the same species. Radiocarbon dating pinpointed their existence during a warmer phase of the middle Weichselian glaciation, when conditions temporarily allowed these animals to survive in central Europe.
Ecological Complexity of the Ice Age
Further genome-wide analysis showed that the European hippo population had extremely low genetic diversity, suggesting it was both small and geographically isolated. Fossil evidence also indicated that these warm-adapted hippos coexisted with cold-climate animals such as mammoths and woolly rhinoceroses, creating an unusual ecological mix that underscores the complexity of Ice Age environments.
“The results demonstrate that hippos did not vanish from middle Europe at the end of the last interglacial, as previously assumed,” summarized Dr. Patrick Arnold, the study’s first author. “Therefore, we should re-analyze other continental European hippo fossils traditionally attributed to the last interglacial period.”
Implications for Future Research
Prof. Dr. Wilfried Rosendahl, general director of the Reiss-Engelhorn-Museen Mannheim and project leader of “Eiszeitfenster Oberrheingraben,” emphasized the ongoing potential for ice age research: “The current study provides important new insights which impressively prove 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.”
This research was conducted as part of the “Eiszeitfenster Oberrheingraben” project, supported by the Klaus Tschira Stiftung Heidelberg. The interdisciplinary effort aims to illuminate the climate and environmental evolution in the Upper Rhine Graben and southwestern Germany over the past 400,000 years. Focusing on Ice Age bones from the Reis collection, housed at the Reiss-Engelhorn-Museen, the study continues to reveal remarkable insights into Europe’s dynamic prehistoric world.
“The study challenges long-held assumptions about the adaptability and resilience of species during the ice age, opening new avenues for understanding past ecosystems,” noted a spokesperson from the research team.
As researchers delve deeper into the mysteries of the Ice Age, these findings not only rewrite historical timelines but also prompt a reevaluation of how climate changes influenced the distribution and survival of species across ancient Europe. The next steps involve expanding the research to include other species and regions, potentially unlocking further secrets of Earth’s climatic past.
