A recent study from the University of Wisconsin shows that ancient human populations may have caused the death of large animals across the globe. It seems that man’s first accomplishment upon reaching new territory was to hunt all its large animals to death. The NY Times reports that this circumstantial evidence comes from a recently revealed fossil record.
Jacquelyn Gill is a graduate student at the University of Wisconsin who led the study. She has uncovered new evidence that suggests that whenever modern humans reached a new continent some 50,000 years ago, all the large fauna quickly disappeared. This happened in Australia, Europe and the Americas.
Climate change and asteroid impacts have long been blamed for the mass extinction of large animals from the Earth. However, Gill and her team conducted an analysis of lake deposits in New York and Wisconsin which has brought new data to this table.
Gill documented the pace of extinction in North America, which is known to have affected all animal species weighing more than about 2,200 pounds and half of those weighing more than about 70 pounds. This report measured the number of spores from large animal dung in the lake deposits, setting the steady disappearance of large animals from 14,800 years to 13,700 years ago.
Also found in the lake deposits were an abundance of broad-leaved trees like oak. The large quantity of these oaks is likely due to not being grazed by large mammals. The teams also found a layer of fine charcoal grains, the result of fires from a large buildup of foliage and wood.
Why is the sequence and dating of these discoveries important? The new data can rule out asteroid or comet impacts as the reason large animals were wiped out. One such impact occurred 12,900 years ago, and these creatures were dead long before.
It also rules out climate change as a possible cause for extinction. The extinction of large animals due to habitat change occurred before the emergence of the so-called new plant communities.
Then there is ancient man. The Clovis people are thought to have been the first people in the Americas. They crossed the land bridge that joined Siberia and Alaska during the last Ice Age, some 13,000 years ago. But butchered mammoth bones that are 14,500 years old have appeared in Wisconsin. These came from pre-Clovis people who could have hunted the large animals to death.
However, Gill and her team are not ready to make any conclusions about the fate of large animals. More plans are in the works to analyze lake bottoms before a final decision will be issued.