Apennine Bears Show Remarkable Genetic Adaptation After Centuries of Human Interaction
A groundbreaking study published in the journal Molecular Biology and Evolution reveals that Italy's Marsican brown bears have evolved to become significantly less aggressive through centuries of close coexistence with humans. Researchers from Italian universities, in collaboration with international institutions, have discovered that this isolated population in the Apennine Mountains has undergone genetic changes resembling accidental domestication over 2,000-3,000 years of human interaction.
The Science Behind the Behavioral Shift
The research team, led by scientists from the University of Ferrara, conducted comprehensive genomic analyses comparing the Marsican brown bears with populations from Central Europe and North America. What they found was striking: the Italian bears possess distinctive genetic variants at 17 genes linked to brain development and behavior, with patterns remarkably similar to those seen in domesticated animals like dogs and foxes.
'Interactions between humans and animals are often dangerous for the survival of a species, but can also promote the evolution of traits that reduce conflicts,' says Giorgio Bertorelle, one of the lead researchers from the University of Ferrara. 'Our findings show that centuries of human pressure have unintentionally selected for calmer temperaments in these bears.'
A Population on the Brink
The Marsican brown bear, also known as the Apennine brown bear, represents one of Europe's most critically endangered mammal populations. With only about 60 individuals remaining in the wild, according to conservation estimates, these bears have been isolated in central Italy's mountainous regions since Roman times. Their habitat has shrunk dramatically due to deforestation, agricultural expansion, and human development, creating what researchers describe as a 'genomic bottleneck.'
The study reveals alarming genetic consequences of this isolation: approximately 66% of the bears' genome consists of identical DNA due to extreme inbreeding. They also carry harmful mutations that could threaten their long-term survival. Yet paradoxically, their reduced aggression toward humans may be the very trait that has allowed their continued existence in such close proximity to human settlements.
Human Selection Pressure: Unintentional Domestication
Researchers propose two possible mechanisms for this evolutionary change. The first suggests that over centuries, humans systematically eliminated more aggressive bears that posed threats to livestock or human safety, leaving only the calmer individuals to reproduce. The second possibility is that the bears themselves adapted behaviorally to survive in their shrinking habitat, developing less confrontational approaches to human encounters.
'What we're seeing is essentially accidental domestication,' explains Bertorelle. 'Centuries of humans killing aggressive bears likely selected for calmer temperaments, with genetic evidence suggesting this behavioral shift is hereditary rather than learned.'
Conservation Dilemmas and Future Implications
The findings present complex challenges for conservationists. While the bears' reduced aggression makes coexistence easier and potentially safer for both humans and bears, their genetic health is severely compromised. The study raises difficult questions about whether to preserve these genetically unique but compromised bears or introduce bolder individuals from other populations that might disperse better but could increase human-wildlife conflicts.
According to the research published on EurekAlert, the bears have also developed distinct physical characteristics, including smaller size and unique facial features compared to other brown bear populations. These physical changes may be linked to their behavioral adaptations and the specific environmental pressures of their isolated mountain habitat.
Broader Implications for Human-Wildlife Coexistence
This research comes at a critical time as communities across Europe and North America grapple with rebounding bear populations resulting from successful conservation efforts. In many regions, increasing human-bear encounters have led to tragic incidents, making the Italian case particularly instructive.
The study suggests that even heavily impacted populations may harbor valuable genetic variants that should be preserved in conservation efforts. 'We need to carefully consider these genetic adaptations when protecting and supplementing animal populations in areas severely threatened by human activity,' emphasizes Bertorelle. 'These bears show us that human-wildlife interactions can drive evolutionary changes that benefit both species.'
As reported by Euronews Green, the Marsican brown bears now serve as a living laboratory for understanding how human activities shape wildlife evolution. Their story offers both hope and caution for conservation efforts worldwide, demonstrating how species can adapt to human presence while highlighting the genetic costs of such adaptation.