Rise and fall of the Beringian steppe bison

Area of Science:

• Paleogenomics
• Quaternary Paleontology
• Mammalian Evolutionary Biology

Background:

• Late Pleistocene megafauna extinctions are often attributed to human overhunting.
• The role of environmental change versus human impact remains debated.
• Bison populations in Beringia are key to understanding these extinction dynamics.

Purpose of the Study:

• To investigate the drivers of population decline in late Pleistocene bison using ancient DNA.
• To reconstruct the genetic history of bison in Beringia throughout the Pleistocene and Holocene epochs.
• To test the hypothesis that human activity caused the extinction of large mammals.

Main Methods:

• Analysis of ancient DNA from bison remains.
• Application of Bayesian statistical methods for phylogenetic reconstruction.
• Correlation of genetic data with paleoclimatic and archaeological records.

Main Results:

• Bison populations in Beringia were genetically diverse until approximately 37,000 years before present.
• A significant decline in genetic diversity began around 37,000 years ago.
• This decline coincided with the onset of the last glacial cycle's environmental shifts.
• Archaeological evidence indicates sparse human populations in Eastern Beringia until over 15,000 years later.

Conclusions:

• Environmental changes during the last glacial cycle, not human predation, likely caused the decline in bison genetic diversity.
• The findings question the prevailing theory of human-driven megafaunal extinctions at the end of the Pleistocene.
• Paleogenomic studies are crucial for re-evaluating the impact of climate versus humans on past ecosystems.