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Marshall professor’s research demonstrates cause of ice age extinction

Dr. Robin O'Keefe
Marshall University’s Dr. Robin O’Keefe has led research that was published today on the cover of the prestigious journal Science and demonstrates that the extinction of ice age mammals — dire wolves, sabretooth cats, horses and other species — was driven by a series of catastrophic fires in Southern California.

O’Keefe, a professor of Biological Sciences at Marshall, and his team used a large sample of new radiocarbon dates on extinct species from the tar pits at Rancho La Brea in Los Angeles. The data show that most species disappeared during a massive fire event that peaked about 13,000 years ago and was caused by humans and climate change.

Having research published on the cover of Science is a tremendous achievement, said Dean Wesley Stites of Marshall’s College of Science.

“To put this in context for non-scientists, Science magazine is arguably the most prestigious place in the world to place peer-reviewed research,” Stites said. “So just getting your work into Science is a lifetime ambition for many scientists. To get into Science means that the paper is thought by the editors to be very influential, of interest to the broad scientific community, and novel. And Robin O’Keefe is the lead author. And the article was selected for the cover of the magazine. It just doesn’t get better than that in scientific publishing. The work of Robin and his team is a scientific home run. Marshall and the College of Science could not be prouder of this gifted researcher.”

O’Keefe’s team’s complex research presents evidence to answer a long-standing question of scientists.

“Humans co-existed with megafauna for thousands of years before the extinction event,” O’Keefe noted. “Why did this event happen when it did?”

The study, funded by a National Science Foundation grant, used rich pollen records and detailed climate proxies to show that the climate in Southern California warmed and dried significantly as the ice age ended. Econometric modeling was then used to analyze causal factors and strongly implicates humans as the primary cause of the fires, both directly through ignition, and indirectly through the elimination of herbivores. However, the fires were also promoted by the warming and drying climate, O’Keefe said. Together, the confluence of human and other factors enabled an ecological state shift, from one ecological regime (megafaunal woodland) to another (human chaparral).

This state shift entailed a major floral reorganization and the elimination of megafauna, O’Keefe said.

“Humans were largely responsible for the extinction, but not through overkill. Increasing human impacts in a warming, drying climate set the stage for ecological catastrophe,” O’Keefe said. “This event is a cautionary tale for today, particularly considering our warming climate.”

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“Dr. O’Keefe’s innovative research highlights how our actions impact the environment’s delicate balance,” said Dr. Avinandan Mukherjee, senior vice president for academic affairs and provost at Marshall. “By understanding our history, we can wisely navigate modern challenges towards a sustainable future.”

O’Keefe has held a faculty position at Marshall since 2006 and has taught over 2,000 undergraduates in courses ranging from human anatomy to comparative zoology and earth history. He has successfully mentored 19 master’s degrees, with two in progress. He received his bachelor’s degree in honors Biology from Stanford University in 1992, and his Ph.D. in Evolutionary Biology from the University of Chicago in 2000.

O’Keefe has published widely in journals including Science, Nature, PNAS, Systematic Biology, and numerous others. An acknowledged expert on marine reptiles from the age of dinosaurs, O’Keefe was named Distinguished John Deaver Drinko Academy Fellow for academic year 2012-2013, and then received a Drinko Distinguished Research Fellowship Grant in 2017 for his work on plesiosaur reproduction. O’Keefe has also published on the anatomy and relationships of Permian reptiles from Africa, as well as a series of papers on the evolutionary biology of Rancho La Brea carnivores. O’Keefe has done paleontological field work in the Caribbean, Madagascar, Niger, China, Europe, and throughout the American West, with current digs in the Cretaceous of Wyoming and Montana.

“Robin O’Keefe’s cover article in Science is very exciting in several ways,” Stites said. “First, the work itself provides insight into how sweeping changes in the ecology of North America took place 13,000 years ago. All sorts of animals that we all learned about in grade school went extinct then, and a long-running question has been how and why they died off. This international team provides solid evidence for the first time that widespread wildfires and the associated changes in habitat are at least part of the answer. And they raise the possibility that humans may have been part of the reason for the fires.

“Dr. O’Keefe’s pivotal role as the leader of a complicated project with 19 investigators across 16 institutions affirms the quality of our faculty and their ability to do cutting-edge work at Marshall,” Stites continued. “And, last but not least, this is serious research work that legitimately includes sabertooths. How impossibly cool is that?”

To learn more about the College of Science at Marshall University, visit



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  1. Dr. Robin O’Keefe