Press Release- A study of weanning age in fossil elephants gives hints about the cause of their extinction

October 21, 2015
DALLAS, TX (October, 2015) – The extinctions of many giant mammals, like mammoths, at the end of the Ice Ages is a story that most people know about.  The causes of these extinctions have long been debated in the scientific literature.  Climate change and over-hunting by humans, as well as a combination of these, have all been argued.  New techniques for interpreting life-history data from fossil tusks may help tease these causes apart.
At the 2015 Society of Vertebrate Paleontology meetings, researcher Michael Cherney of the University of Michigan, presented findings about weaning age (i.e. when a calf stops nursing) in fossil mammoths.  By studying modern African elephants at the Toledo Zoo, Cherney was able to characterize the isotopic effects of weaning in a close relative of mammoths.  Decreased nursing causes predictable changes in the isotopic composition of elephant tail hairs sampled over time.
The key to Cherney’s research is that these same nitrogen isotopes are preserved in fossil mammoth tusks, which grew throughout life.  Records of early life history in tusks from juvenile mammoths can be used to determine the age at which individuals were weaned.  He combined this with the knowledge that climate stress has been associated with delayed weaning in modern elephants, while overhunting of can lead to accelerated maturation in populations.  His results suggest that weaning age in Siberian woolly mammoths decreased leading up to extinction. This is inconsistent with climate change being the cause of extinction and provides evidence for overhunting shortly before they went extinct.
“I think analysis of life-history data from fossil proboscidean tusks is a tool that could resolve questions concerning the late Pleistocene extinctions of various fossil elephant species. These insights also give context for understanding other contemporaneous extinctions and the impact of past human populations on their environments,” said Cherney.
About the Society of Vertebrate Paleontology
Founded in 1940 by thirty-four paleontologists, the Society now has more than 2,300 members representing professionals, students, artists, preparators, and others interested in VP. It is organized exclusively for educational and scientific purposes, with the object of advancing the science of vertebrate paleontology.
Society of Vertebrate Paleontology website:
Journal of Vertebrate Paleontology
The Journal of Vertebrate Paleontology (JVP) is the leading journal of professional vertebrate paleontology and the flagship publication of the Society. It was founded in 1980 by Dr. Jiri Zidek and publishes contributions on all aspects of vertebrate paleontology.
Journal Web site:

Michael Cherney
University of Michigan
Ann Arbor, MI, USA