By Molly E. Hunt
When did mammoths go extinct? This question is at the forefront of a recent study conducted by Dr. Joshua Miller, a University of Cincinnati professor, and co-author Dr. Carl Simpson from the University of Colorado Boulder.
Mammoths are a type of megafauna (extinct large or giant animals from a geological period) that once inhabited North America, Africa, Europe, and Asia. These elephant-like herbivores were equipped with a proboscis or trunk (elongated nose) and long curved tusks. Several different types of species of mammoths once roamed Earth, including Mammuthus subplanifrons (South African Mammoth), Mammuthus exilis (Pygmy Mammoth), Mammuthus meridionalis (Southern Mammoth), and those found in Ohio, Mammuthus columbi (Columbian Mammoth) and Mammuthus primigenius (Woolly Mammoth).
From the popular Ice Age movie franchise to fossil skeletons in museums worldwide, mammoths play a large role in the public’s interest in paleontology. Perhaps this is because of the interaction of this mammal and early humans.
Many people associate the extinction of mammoths with the end of Earth’s most recent Ice Age approximately 11,000 years before present (BP). However, a study conducted by an international team published findings in Nature disputing this timeline. Wang and others1 concluded based on their findings that mammoths met their fate at a significantly earlier time.
The published results come from looking at eDNA (environmental deoxyribonucleic acid) found within sediments in the permafrost of Siberia. eDNA is mitochondrial DNA that is released by an organism into the environment. DNA is the hereditary material in organisms that defines biological instructions. The chemical structure of DNA is the same for all living things, but differences in the order of DNA help identify individuals, species, or populations. Sources of eDNA from a living organism include feces, mucus, skin, and hair. When an organism dies, its DNA is released through the decay of the carcass. The unique environment of Siberian permafrost has allowed the preservation of eDNA from extinct animals. The results of Wang and others suggest that mammoths survived in both North America and Eurasia until about 4,000 years BP, into the Holocene Epoch
In their rebuttal paper also published in Nature, Miller and Simpson2 critique the results from the eDNA, as an organism contributes DNA to sediments during its life and for a significant amount of time after death. Additionally, sedimentary deposits can be complex materials of different ages buried together, which causes errors in dating methods. Miller and Simpson believe that the slow decomposition of animals in the permafrost could explain for the persistence of eDNA thousands of years after the death of a particular animal.
Miller and Simpson express concerns about the lack of physical bone evidence in the original study. They note that there is a nearly continuous record of mammoth fossils in North America, Northwest, Northeast, and Central Siberia that tell a different story. Using radiocarbon dating of bones from North America and Northeast Siberia, their research indicates a mammoth extinction timeline of between 10,000–13,000 years BP. In Northwest and Central Siberia, bones indicate extinction at around 10,000–9,000 years BP. Miller and Simpson conclude that mammoths went extinct between 10,000–13,000 years BP, with a few remote island locations as an exception.
Extinction is a truly important factor in the understanding of the biological past. It is vital for us to fully understand a species timeline. Their work will continue to inform our understanding of taphonomy (the branch of paleontology that focuses on the process of decay and preservation in the fossil record) and the impact humans may have on the global extinction of mammoths.
References
1 Wang, Y., Pedersen, M.W., Alsos, I.G., and others, 2021, Late Quaternary dynamics of Arctic biota from ancient environmental genomics: Nature, v. 600, p. 86–92. https://doi.org/10.1038/s41586-021-04016-x
2 Miller, J.H., and Simpson, C., 2022, When did mammoths go extinct?: Nature, v. 612, p. E1–E3. https://doi.org/10.1038/s41586-022-05416-3