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The African elephant, the largest terrestrial mammal alive, poses a threat to tree growth in the steppe.

The onset of the anthroposphere


12 000 years ago, humans replaced megaherbivores in terrestrial ecosystems. Megaherbivores are extremely large, terrestrial plant eaters that weigh over a ton when fully grown. While today only a handful of species remain in the tropical regions of Africa and Asia, things were different in the past 300 million years. Just consider the dinosaurs. Megaherbivores were widespread on all continents; until 12 000 years ago, mammoths, woolly rhinoceroses, and giant sloths roamed the land and played a key role in many terrestrial ecosystems.

Animals as Ecosystem Engineers

Due to their size alone, megaherbivores perform functions that cannot be met by smaller herbivores. They change the vegetation, keep landscapes open, and they carry plant seeds in their digestive tract over many kilometers, thus allowing the plants to populate new locations. Elephants,
for example, are the most significant distributers of large seeds in the forests of Central Africa. Megaherbivores alter the ecosystems’ structure and species composition. They recycle and spread nutrients and make them available for plants, which ultimately benefits the biodiversity.

Dramatic ecological shift caused by and benefiting humans

12 000 years ago, the conditions underwent a fundamental change. Humans settled down and began to produce food instead of collecting it.
They cut down forests and improved the nutrient recycling in the soil by tilling it and introducing animal excrements as fertilizer. Even the early farmers contributed to the emission of carbon dioxide due to deforestation; animal husbandry led to an increased release of methane, which eventually added to the warming of the climate. Wherever the climate conditions were not too extreme for agriculture, humans switched from hunting and gathering to farming and animal husbandry – but only after the megaherbivores that once lived there had disappeared. Thus, the exploitation of a new ecological niche by humans did not happen due to displacement. However, in some cases the extinction of megaherbivores as a prerequisite for wide-ranging ecosystem changes had been caused by humans tens of thousands of years earlier, since humans hunted these large animals that previously had practically no natural enemies.

What does this mean? Homo sapiens has altered his ecological niche. First, man as a predator significantly affected the extinction of a guild– i. e., the megaherbivores – followed by the occupation of large parts of their previous ecological niche. This process is unique in geological history and occurred at a much faster rate than the evolution of new species.

A Global ecologicak transition with locally different effects

In certain areas – such as the agriculturally unsuitable subarctic, the former home of the mammoth – the extinction of megaherbivores led to far-reaching ecosystem changes. Previously, the giant animals had restricted the growth of trees, giving other plants sufficient space and nutrients to grow – with the aforementioned beneficial effect on biodiversity. With the disappearance of the megaherbivores, the steppes transitioned into boreal coniferous forests, which in turn affected the global climate. The result was a reduction of the so-called “albedo effect:” Contrary to a white snow cover in the winter or a yellow landscape dominated by dry grass in the summer, the dark green forests absorb the solar radiation to a much higher degree, causing a warming of the climate. Moreover, the soils of the mammoth steppe were drier and emitted lower levels of methane. Could it therefore be beneficial – to increase biodiversity and curb the global warming – to reintroduce
large herbivores in certain regions of our earth? In this context, the question arises how the individual representatives of the extinct megafauna influenced the ecosystems and climate at that time, and whether these results can be applied to recent animals as well – a highly interesting research question. At any rate, the reintroduction of large herbivores could potentially revive certain ecological functions; the nutrient cycle and biomass production would receive a boost; and it might possibly mitigate climate change – although additional  paleobiological studies will be required to answer this last question.

Team HEP Bocherens
Prof. Dr.  Hervé Bocherens
Leader of the AG Biogeology in HEP
Phone +49 7071 29-76988
herve.bocherens@senckenberg.de

Main research interests
• Interaction of primates, hominins and humans with their environment through time
• Evolution of mammalian communities in interaction with their environment
• Isotopic tracking of terrestrial paleoecosystems
• Conservation paleobiology

Since 2008 Professor, Chair of Biogeology, Department of Geosciences, Univ. Tübingen (Germany)
2006 – 2007 Invited Researcher, Institut für Ur- und Frühgeschichte und Archäologie des Mittelalters, Univ. Tübingen (Germany)
2005 – 2006 Humboldt Foundation Senior Research Fellow, Institut für Ur- und Frühgeschichte und Archäologie des Mittelalters, Univ. Tübingen (Germany)
2003 – 2004 Invited Researcher, Prairie & Northern Wildlife Research Centre, Canadian Wildlife Service, Environment Canada, Saskatoon (Canada)
2001 – 2008 Associate Researcher, CNRS, Inst. Sciences de l’Evolution, Univ. Montpellier 2 (France)
1996 – 2001 Associate Researcher, CNRS, Lab. Biogéochimie Isotopique, Univ. Paris 6. (France)
1994 – 1996 Assistant Researcher, CNRS, Lab. Biogéochimie Isotopique, Univ. Paris 6. (France)
1992 – 1994 Post-Doctoral Fellow, Carnegie Institution & Smithsonian Institute, Washington D.C. (USA)

List of Publications (10 exemplary publications of the last 4 years – out of 180 peer-reviewed articles since 1988)

  • Bocherens, H., 2018. The rise of the anthroposphere since 50,000 years: an ecological replacement of megaherbivores by humans in terrestrial ecoystems? Frontiers in Ecology and Evolution 6:3. https://doi.org/10.3389/fevo.2018.00003

  • Bocherens, H. 2019. Isotopic insights on cave bear palaeodiet. Historical Biology 31: 410-421. https://doi.org/10.1080/08912963.2018.14465419

  • Bocherens, H., Díaz-Zorita Bonilla, M., Moncel, M.-H., Daujeard, C., Raynal, J.-P., 2016. Direct isotopic evidence for subsistence adaptability in middle Pleistocene Neandertals (Payre, southeastern France). Quaternary Science Reviews 154: 226-236. https://doi.org/10.1016/j.quascirev.2016.11.004

  • Bocherens, H., Cotte, M., Bonini, R., Straccia, P., Scian, D., Soibelzon, L., Prevosti, F.,J., 2017. Isotopic insight on paleodiet of extinct Pleistocene megafaunal xenarthrans from Argentina. Gondwana Research 48: 7-14, https://doi.org/10.1016/j.gr.2017.04.003

  • Drucker, D.G., Naito, Y.I., Péan, S.C., Prat, S., Crépin, L., Patou-Mathis, M., Chikaraishi, Y., Ohkouchi, N., Puaud, S., Lázničková-Galetova, M., Yanevich, A., Bocherens, H., 2017. Isotopic analyses suggest mammoth and plant in the diet of the oldest anatomically modern humans from far southeast Europe. Scientific Reports 7: 6833. https://doi.org/10.1038/s41598-017-07065-3

  • Hofman-Kaminska, E., Bocherens, H., Borowik, T., Drucker, D.G., Kowalczyk, R., 2018. Stable isotope signatures of large herbivore foraging habits across Europe. PLoS ONE 13(1): e0190723. https://doi.org/10.1371/journal.pone.0190723

  • Ma, J., Wang, Y., Jin, C., Hu, Y., Bocherens, H., 2019. Ecological flexibility and differential survival of Pleistocene Stegodon orientalis and Elephas maximus in mainland southeast Asia revealed by stable isotope (C, O) analysis. Quaternary Science Reviews 212 : 33-44. https://doi.org/10.1016/ j.quascirev.2019.03.021

  • Owocki, K., Kremer, B., Cotte, M., Bocherens, H., 2019. Diet preferences and climate inferred from Oxygen and Carbon isotopes of tooth enamel of Tarbosaurus baatar (Nemegt Formation, Mongolia) Palaeogeography, Palaeoclimatology, Palaeoecology in press. https://doi.org/10.1016/j.palaeo.2019.05.012

  • Posth, C., Wißing, C., Kitagawa, K., Pagani, L., Racimo, F., van Holstein, L., Wehrberger, K., Conard, N.J., Kind, C.J., Bocherens, H., Krause, J., 2017. Deeply divergent archaic mitochondrial genome provides lower time boundary for African gene flow into Neandertals. Nature Communications 8: 16046. https://doi.org/ 10.1038/ncomms16046

  • Wißing, C., Rougier, H., Baumann, C., Comeyne, A., Crevecoeur, I., Drucker, D.G., Gaudzinski-Windheuser, S., Germonpré, M., Gómez-Olivencia, A., Krause, J., Matthies, T., Naito, Y.I., Posth, C., Semal, P., Street, M., Bocherens, H., 2019. Stable isotopes reveal patterns of diet and mobility in last Neandertals and first modern humans in Europe. Scientific Reports 9:4433. https://doi.org/10.1038/s41598-019-41033-3

 

see also Research-ID (F-3580-2011) and ORCID-ID (0000-0002-0494-0126)

pdfs of (almost) all publications can be downloaded at:

Researchgate (https://www.researchgate.net/profile/Herve_Bocherens/research)

Academia (https://uni-tuebingen.academia.edu/HerveBocherens/Papers)