American Scientist

To the Editors:

In the Spotlight report “New Information from Ancient Genomes” by Sandra J. Ackerman (September–October), I question the statement on page 327 that Eske Willerslev’s data “constitute a strong case that climate change—not hunting—caused the last great extinction.” Others argue that the extinction of the megafauna caused changes in the vegetation, not the other way around.

Richard Gillespie, PhD
University of Wollongong
Wollongong, Australia

Editors’ Note:

We asked Dr. Willerslev to comment on this question, and he said: “In the scientific community the processes causing the extinction of the Late Quaternary megafauna of the Northern Hemisphere, such as the woolly mammoth and woolly rhinoceros, are heavily debated. The statement that these extinctions were due to climatic changes that caused shifts in vegetation is based on two recent papers from my groups: Lorenzen et al. ( Nature 2011) and Willerslev et al. ( Nature 2014). In my view the former, which is the largest scale population genetic study to date on Late Quaternary megafauna, clearly shows climate as the main driver of population size changes in these animals. The latter demonstrates that climate change during the Late Quaternary resulted in severe vegetation changes and the loss of key food sources for the megafauna.”