How did climate change affect Pleistocene megafauna?

Submitted by Sammy Smith (sammy@thesga.org)

Did people kill off Pleistocene megafauna in North America, or were those species done in by climate shifts? Or…?

This question is still not answered unambiguously.

However, research by Jacquelyn Gill of the University of Wisconsin—Madison shows that neither scenarios is probable based on fossil pollen, charcoal and dung fungus spores that date to just after the ice retreated. Neither the mass extinction model, based on heavy hunting, nor simple climate and thus habitat change matches the data she and colleagues Stephen T. Jackson (University of Wyoming), Katherine B. Lininger (University of Wisconsin—Madison), and Guy S. Robinson (Fordham University) have marshalled.

According to Terry Devitt’s story (19 November 2009) on the University of Wisconsin—Madison website:

The decline of North America’s signature ice age mammals was a gradual process, the Wisconsin researchers explain, taking about 1,000 years. The decline in the huge numbers of ice age animals is preserved in the fossil record when the fungal spores disappear from the record altogether: “About 13.8 thousand years ago, the number of spores drops dramatically. They’re barely in the record anymore,” Gill explains.

Devitt continues:

While both the extinction of North America’s ice age megafauna and the sweeping change to the landscape are well-documented phenomena, there was, until now, no detailed chronology of the events that remade the continent’s biological communities beginning about 14.8 thousand years ago. Establishing that the disappearance of mammoths, giant beavers, ground sloths and other large animals preceded the massive change in plant communities, promises scientists critical new insight into the dynamics of extinction and its pervasive influence on a given landscape.

Archaeologists are often confronted with this situation: how do we get data on human behavior or the human situation, when we don’t have it directly from the archaeological record of human occupations? This research by Gill and her colleagues shows one solution developed to help understand the ecological situation in interior North America early in human occupation of the continent.

Stand by for more data….