Minks Evolve Domesticated Brains to Bigger Feral Brains in 50 Generations

A recent study demonstrates that American minks may evolve from having smaller domesticated brains to larger feral brains after 50 generations.

Smaller Domesticated Brains

Farm animals with smaller brains than their wild counterparts include sheep, pigs, and cows, demonstrating the constant domestication impact.

The American mink exhibits a distinctive domestication effect reversal, according to the Max Planck Institute. Captive-bred populations had smaller brains, but freed populations quickly recovered the size of their ancestors.

Lead author Ann-Kathrin Pohle of MPI-AB finds that domesticated animals can experience temporary brain size decrease. This knowledge improves our comprehension of how domestication affects animal brains and their reintroduction to the wild.

Bigger Feral Brains

Loss of brain volume during domestication is frequently irreversible. Even feral populations that have survived for decades in the wild rarely grow back to their ancestral brain sizes. It is made clear by MPI-AB group leader Dina Dechmann that lost bodily or mental components cannot be acquired again through evolution. Dechmann is the senior author of the paper recently published in the journal Royal Society Open Science.

American Mink

Studying the reacquisition of relative brain sizes in feral animals is difficult from a methodological standpoint. Dechmann highlights the requirement for distinct wild and feral populations that do not interbreed in order to achieve reliable results. Due to the presence of wild, domesticated, and feral populations, the American mink meets these requirements.

It was domesticated in Europe for the purpose of raising fur animals, and after some of the animals escaped, feral populations spread throughout the continent. The investigation of Dechmann and his team was aided by this distinctive natural history.

The team looked into changes in brain size using skulls as a proxy. According to Pohle, the size of a mink's braincase is a reliable predictor of that animal's brain size. Skulls from European fur farms and a museum collection from Cornell University were used to measure existing skull collections.

Measuring Brains

Dechmann and Pohle got skull collections from a feral mink eradication effort in cooperation with Andrzej Zalewski at the Polish Mammal Research Centre. It can be difficult to locate enough skull collections for investigations, but the team was lucky to collaborate with several groups.

They used the skulls to estimate relative brain size and found that captive-bred mink had a 25% smaller brain than their wild predecessors. Surprisingly, despite concerns of irreversibility, feral mink demonstrated brain regeneration, almost returning their brain size to the proportions of their wild counterparts within 50 generations.

Ancestral Brain Sizes

Dechmann has a hypothesis about how the American mink managed to do what appeared to be impossible. The Dehnel's phenomenon, which Dechmann has observed in moles, shrews, and weasels, allows small animals like this species to change their brain size in response to the seasons.

The Dehnel phenomenon is the shrew's cranium contracting in the winter and expanding again in the spring. There is also a risk for other organs like the liver and kidneys. Due to this adaptability, the need for food during the winter can be decreased, according to Futura-Sciences.

Due to their innate flexibility, mink may regain their original brain sizes, unlike other domesticated animals that do so permanently. If mink were to be reintroduced to the wild, their flexibility might be advantageous because they would need a fully working brain to deal with the obstacles in their environment. The mink's brain was flexible enough to allow for recovery, even though it had previously shrunk while in captivity.

The findings do not indicate whether feral mink brains function similarly to those of wild-type mink. The team would need to examine animal brains, which is a step for a subsequent study, to determine that, Phys Org reports.