In a groundbreaking study, researchers from the Max Planck Institute of Animal Behavior (MPI-AB) have discovered a rare reversal of the domestication effect in the American mink. The study, published in the Royal Society Open Science, found that populations of mink that escaped from captivity were able to regain almost the full ancestral brain size within 50 generations.
The domestication effect refers to the smaller relative brain sizes observed in domesticated animals compared to their wild counterparts. This phenomenon has been observed in various farm animals such as sheep, pigs, and cows. However, the American mink has shown the ability to reverse this trend.
“Our results show that loss of brain size is not permanent in domesticated animals,” says Ann-Kathrin Pohle, a Master’s student at MPI-AB and first author of the study. “This finding deepens our understanding of how domestication has changed the brains of animals, and how these changes might be affecting animals when they return to the wild.”
Typically, animals that undergo domestication do not regain the relative brain sizes of their wild ancestors, even in feral populations that have been living in the wild for generations. However, the American mink has demonstrated the ability to recover its ancestral brain size.
To study this phenomenon, the researchers measured skull sizes as a proxy for brain size. They used a collection of wild American mink skulls from Cornell University, European fur farms for domesticated mink skulls, and skulls from feral mink obtained from an eradication program in Europe. The team found that the brains of captive-bred mink had shrunk by 25% compared to their wild ancestors, but the brains of feral mink grew almost back to the wild size within 50 generations.
The researchers speculate that the American mink’s ability to achieve this reversal is due to their flexibility in brain size changes. The mink belong to a family of small mammals that can seasonally change their brain size, known as Dehnel’s phenomenon. This flexibility in brain size could offer advantages to mink re-entering the wild, allowing them to navigate the challenges of living in the wild with a fully capable brain.
While the study reveals an intriguing reversal of the domestication effect, it does not provide information on whether the brains of feral mink function the same as wild-type mink. Further studies would be needed to understand the functional implications of these brain size changes.
This study sheds new light on the fascinating adaptations that occur in the brains of domesticated animals and their ability to readapt to the wild. The findings have implications for our understanding of the effects of domestication on animal cognition and behavior.