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A new study led by researchers at the University of Oulu, Finland has uncovered striking changes in the skull shape of wolves in Finland, Sweden and Norway, reflecting a major population turnover during the 20th century.

, published in the journal Royal Society Open Science, shows that modern wolves in Fennoscandia differ significantly in cranial morphology from their historical counterparts. These changes align with known genetic replacements among wolves following extinction in Norway and Sweden and near-extinction in Finland.

Using advanced 3D imaging and geometric morphometrics, the team analyzed 84 wolf skulls collected over the past 200 years. They found that modern Scandinavian wolves in Norway and Sweden have wider frontal bones, higher cheekbones, and more downward-sloping snouts compared to wolves that lived before the population collapse in the 1960s. In Finland, similar but less pronounced changes were observed.

"These morphological shifts mirror the genetic changes that occurred when wolf populations were decimated by hunting and later re-established by a small number of immigrants," says lead author, Doctoral Researcher Dominika Bujnáková from the Ecology and Genetics Research Unit at the University of Oulu.

The study also suggests that changes in prey availability—particularly the recovery of moose populations—may have influenced skull shape, as wolves transitioned from hunting smaller prey to hunting moose. Additionally, the researchers found that zoo-born wolves and undated museum specimens showed distinct cranial features, highlighting the importance of context in interpreting morphological data.

This research provides new insights into how environmental and genetic factors interact to shape animal morphology over time. "The results serve as a reminder that both direct and indirect human activities can leave lasting marks on wildlife— not only in their genes, but also in how they look and live," Bujnáková concludes. The study also underscores the value of museum collections and modern imaging techniques in tracking long-term changes in wildlife populations.