From wild to mild: Friendly foxes show changes in brain region

A Cornell-led study published Nov. 2 in Current Biology found that tame silver foxes bred in a decades-long Siberian domestication experiment have fewer aggression-linked neurons expressing estrogen receptor alpha in the ventromedial hypothalamus than their aggressive and wild counterparts. The research, led by Eirene Markenscoff-Papadimitriou, an assistant professor of molecular biology and genetics at Cornell's College of Agriculture and Life Sciences, compared thinly sliced brain tissue from nine foxes—three tame, three aggressive and three wild—using fluorescent RNA scope markers to identify cell types in the brain region. The tame foxes descended from a program begun in the late 1950s, when Russian geneticists selectively bred animals that were friendlier toward caretakers and produced human-friendly litters within six generations, along with domestication traits such as floppy ears and shorter snouts. The finding matters because it links rapid behavioral change under selective breeding to a specific neural circuit, suggesting environmental pressures can reshape brain structure on short timescales. Next, the researchers aim to determine why domestication produces these changes in the ventromedial hypothalamus.