Ancient DNA Reveals How American Bison Survived Near-Extinction and Were Managed by Indigenous Peoples

Introduction: Unraveling the Bison's Genetic Past

The American bison, an iconic symbol of the Great Plains, has a history far more complex than previously understood. A new paleogenomic study, published in the journal Science, provides unprecedented insights into the species' collapse, recovery, and long-standing relationship with Indigenous peoples. By analyzing ancient DNA from bison remains, researchers have reconstructed a detailed genetic timeline that challenges conventional narratives and highlights the role of human management in bison survival.

The Genetic Collapse: A Near-Extinction Event

The study reveals that American bison experienced a severe population bottleneck approximately 30,000 years ago, during the Pleistocene. This collapse, likely driven by climate change and habitat shifts, reduced the genetic diversity of bison to a fraction of what it once was. The genomic data shows a sharp decline in effective population size, followed by a slow recovery that spanned millennia. This finding underscores the resilience of bison, but also their vulnerability to environmental pressures.

Evidence from Ancient Genomes

Researchers sequenced mitochondrial and nuclear genomes from bison fossils dating back to the last glacial maximum. The data indicate that the bottleneck was more severe than previously estimated, with a loss of up to 90% of genetic diversity. This genetic erosion had lasting impacts on the species, affecting their adaptability to subsequent environmental changes.

Recovery and Expansion: A Slow Rebound

Following the bottleneck, bison populations gradually rebounded, expanding across North America. The genomic evidence shows a steady increase in population size starting around 15,000 years ago, coinciding with the retreat of glaciers and the expansion of grasslands. However, the recovery was not uniform, with distinct genetic lineages emerging in different regions. This regional differentiation suggests that bison populations were isolated at times, leading to local adaptations.

Human Influence on Recovery

Intriguingly, the study suggests that Indigenous peoples played a significant role in bison recovery and management. Archaeological and genetic evidence indicate that bison were not merely hunted but actively managed through practices such as controlled burns to maintain grasslands and selective hunting to preserve breeding populations. This management may have facilitated the genetic recovery of bison by preventing further bottlenecks and promoting gene flow between populations.

Indigenous Management: A Co-Evolutionary Story

The relationship between bison and Indigenous peoples is one of the oldest and most enduring human-animal partnerships in North America. The new genomic data provides a molecular basis for this co-evolution. By comparing ancient bison genomes with modern ones, researchers identified signatures of selection that may be linked to human management. For example, genes associated with docility and herd behavior show signs of positive selection in bison populations that were intensively managed by humans.

Cultural and Ecological Significance

This research challenges the notion that bison were purely wild animals until European colonization. Instead, it suggests that Indigenous peoples were active stewards of bison populations, shaping their genetics and ecology for thousands of years. This has profound implications for modern conservation efforts, which often aim to restore bison to their 'natural' state. The study argues that conservation strategies should recognize the historical role of Indigenous management and incorporate traditional ecological knowledge.

Implications for Modern Conservation

The findings have immediate relevance for bison conservation and management. Many modern bison herds are descended from a small number of individuals that survived the 19th-century slaughter, leading to low genetic diversity and health issues. The paleogenomic data offers a roadmap for restoring genetic diversity by identifying source populations that harbor unique alleles lost in modern herds. Additionally, the study emphasizes the importance of maintaining connectivity between herds to promote gene flow, a strategy that aligns with Indigenous land management practices.

Integrating Traditional Knowledge

Conservationists are increasingly recognizing the value of Indigenous knowledge in wildlife management. This study provides a scientific basis for such integration, showing that bison and humans have a shared history of mutual dependence. By partnering with Indigenous communities, conservation programs can enhance bison resilience while also respecting cultural traditions.

Conclusion: A New Perspective on Bison History

The paleogenomic analysis of American bison offers a compelling narrative of collapse, recovery, and human partnership. It reveals a species that has endured dramatic genetic losses but also demonstrates remarkable resilience, aided by human stewardship. As we face current biodiversity crises, this study serves as a reminder that conservation is not just about preserving species in isolation, but about understanding and restoring the intricate relationships between humans and the natural world. The bison's story is a testament to the power of genomic research to illuminate the past and guide the future.

This article is based on reporting by Science (AAAS). Read the original article.