Wild mammals
Tame foxes show cellular changes in brain region
Researchers examining domesticated silver foxes found fewer aggression-linked neurons in a key brain region compared with wild and hostile counterparts.
Reported by Phys.org · · 2 min read
A new neurological investigation has revealed that foxes bred for friendliness exhibit distinct cellular differences in a part of the brain linked to aggressive actions. By examining tissues from silver foxes displaying contrasting behavioral traits, researchers discovered alterations within the ventromedial hypothalamus, a structure located near the base of the brain that influences social behavior, maternal drives, and energy choices.
The findings, published in the scientific journal Current Biology, draw from a famous breeding project launched in Siberia during the late 1950s. At that time, Russian geneticists began pairing foxes that showed gentle responses toward their human handlers. Within merely six generations, the selective breeding yielded pups willing to socialize with people, alongside physical shifts typical of tamed species, including shortened snouts and drooping ears.
Senior author Eirene Markenscoff-Papadimitriou, an assistant professor at Cornell University, explained that the team sought to understand the neural mechanisms driving such swift behavioral transformations. She noted that their discoveries also shed light on how varied environmental pressures can modify brain architecture over remarkably short spans of time.
To inspect the underlying neurology, investigators analyzed nine preserved fox brains provided by researchers managing the Russian colonies. The sample included three specimens from docile animals, three from lineages bred for hostile temperament, and three from wild canids. Using fluorescent RNA imaging across fine brain slices, the scientists mapped specific cell populations within the ventromedial hypothalamus.
Previous studies involving laboratory mice demonstrated that stimulating neurons carrying estrogen receptor alpha in this hypothalamic zone prompted animals to attack one another without hesitation. Testing whether these cells varied in foxes, the researchers detected significantly fewer of these specific receptor-bearing cells in the brains of gentle foxes compared to their aggressive and untamed peers.
Co-author Anna Kukekova from the University of Illinois Urbana-Champaign plans to investigate how genomic variations might guide the formation of these specialized brain cells. The research team intends to explore why selective pressures during domestication specifically reshape this historically understudied hypothalamic region.
