Italian bears are evolving! They are becoming smaller and more docile near villages.

“Next to the Village” Changed the Bears—Genomes Indicate Miniaturization and "Taming"

When we think of coexistence with wildlife, we often imagine a narrative where "humans endure, animals adapt, and they find a way to get along." However, new research surrounding the **Apennine brown bear (Ursus arctos marsicanus)** living in the Apennine Mountains of central Italy shows that coexistence can influence even "character" and "physique," as indicated by genetic traces. The conclusion is provocative—bears living near villages may have evolved to become smaller and less aggressive. Phys.org

This population is unique in its conditions. According to research, the Apennine brown bear diverged from other European brown bear populations about 2,000 to 3,000 years ago and has been strongly isolated for a long time, at least since Roman times. It is suggested that human history, deforestation, agricultural development, and increased human density may have deepened this isolation. Phys.org

What's happening? "Smaller body," "distinctive face," "low aggression"

The Apennine brown bear is considered to be smaller in body size, with distinctive head and facial features (cranial morphology), and lower aggression compared to brown bears in other regions. Phys.org

This study goes beyond mere observation of "appearance" and delves into why this has occurred by comparing genomes.

Research Method: Creating a Reference Genome and Comparing with Other Populations

The research team first constructed a high-quality reference genome at the chromosomal level for the Apennine brown bear and resequenced the entire genome of multiple individuals. For comparison, they also used genomes from other European populations (Slovakian population) and previously reported data from North American brown bears. Phys.org

The results are "as expected, severe" in the context of conservation. The Apennine brown bear has low genetic diversity and a high degree of inbreeding. Furthermore, the abstract of the paper reports that the realized genetic load is greater than in other populations. This is a typical extinction risk faced by small, isolated populations. Phys.org

Moreover, the estimated population size is about 50 individuals, making it susceptible to genetic drift. OUP Academic

Nonetheless, traces of "selection" were observed—Genetic regions related to aggression

Here's the main point. The study picked up signals of adaptation (selection), not just mere "deterioration (loss of diversity)." The abstract of the paper mentions that in the Apennine brown bear, traces of selection were observed in genes related to reduced aggression (e.g., DCC, SLC13A5). OUP Academic

Notably, many of these mutations are located in non-coding regions rather than directly altering protein sequences (coding regions), and some are predicted to affect splice factor binding sites. This suggests that the complex trait of "aggression" may be influenced by the regulation of gene "on/off" states and "re-interpretation." OUP Academic

Why "Taming" Occurs: The Hypothesis of Human-Induced Selection Pressure

The scenario presented by the research is as follows. Over a long timeline, individuals that survive close to human settlements are more likely to possess traits that reduce conflicts with humans. Conversely, individuals prone to conflicts—those that are "more aggressive"—are more likely to be eliminated by humans. The paper and the Phys.org article suggest that more aggressive individuals being removed by humans may have led to selection towards lower aggression. Phys.org

However, it is important to note that this is not a "story of humans kindly 'taming' bears." Behind this lies population reduction and isolation (i.e., genomic erosion) due to deforestation and land use changes. The paper discusses that a strong bottleneck thousands of years ago aligns with agricultural expansion and forest reduction. OUP Academic

Even if taming occurs as a "result" of coexistence, it is often a passive adaptation for survival and simultaneously a condition that increases extinction risk.

Implications for Conservation: "Restocking" is Not a Panacea

Here, the discussion connects to reality. When population numbers are low, the idea of "introducing individuals from other regions to increase genetic diversity" tends to surface. However, the research suggests that even in populations under strong anthropogenic pressure, they may "retain genetic variants that reduce conflicts" and should not be diluted lightly. Phys.org

Thus, conservation is not just about "increasing numbers" but also about the challenging question of "how to handle the traits that have coexisted with the land."

Reactions on Social Media: Empathy, Guilt, and Criticism of "Generalization"

This topic has quietly spread on social media since its announcement. At least in the comments section of Phys.org, there are zero comments at the time of posting, but it has been posted in the evolution community on Reddit, showing several typical reactions. Phys.org

1) Emotions of "Humans Have Changed Nature Too Much"
There are voices interpreting it as a "summary of emotions" rather than factual relationships, such as "Man, we really killed nature, huh." Reddit
Even if the study indicates "taming," given the background of reduction and isolation, such reactions are natural.

2) Curiosity and Requests for Explanation on "Aggression Genes"
Questions like "What exactly do traces of selection mean?" delve into the difficulty of discussing behavioral traits from genomes. Reddit
This is a healthy reaction, and the paper also directly addresses the classic issue of whether behavior is plasticity (learning/environmental factors) or genetic. OUP Academic

3) Generalization of "Everything Will Turn Out the Same"
Comments like "All animals surviving near civilization should have the same tendency" generalize the results broadly. Reddit
However, selection pressures vary greatly by region, species, and management policy. It is reasonable to read this case as a "strong example" where conditions like long-term isolation, small population, and proximity to humans overlap.

The same Phys.org article has also been linked in the bear-loving community (r/bears), indicating that interest is spreading beyond specialized communities. Reddit

Reflecting on Japan

In Japan, whenever news of Asiatic black bears appearing or causing human injuries arises, the discussion often revolves around the binary choice of "extermination or protection." However, the research presented here challenges us with the fact that our actions can change not only **"the individual at that moment" but also, over a long period, "the nature of the population."**

Even if management to reduce conflicts is necessary, we must design it to consider which individuals survive and what traits are passed on to the next generation—otherwise, coexistence will be left to chance.

Conclusion: Coexistence Cannot Be Achieved by "Kindness" Alone

The "taming" of the Apennine brown bear is more of a warning than a hopeful story. The pressure created by human expansion has shrunk populations, reduced genetic diversity, and increased extinction risk. At the same time, it has created room for traits that avoid conflicts to be selected. Phys.org

The lesson we should take is not that "it's good that bears have become gentle," but rather—coexistence is a long-term battle involving environment, management, and evolution, and the results always come with a price.