Czech scientist finds moles can shrink their brains in wintertime
The common European mole, immortalised as Zdeněk Miler’s beloved cartoon character in animated films, now has another Czech connection – a Czech scientist was part of the team that discovered the mole’s unusual evolutionary tactic for surviving winter.
Animals living in colder climates face an existential problem in the wintertime – their bodies require more food than is available to them during the coldest months of the year. Different species have developed various evolutionary strategies to deal with this conundrum – birds migrate to warmer climes, bears and squirrels hibernate, and humans learned how to grow their own food and store it. But moles, as Czech scientist Lucie Farková Nováková has helped to unearth, have developed an altogether different energy-saving tactic – they shrink their brains.
This phenomenon was not unknown to science before the Czech scientist’s team at the Max Planck Institute of Animal Behaviour found it in European moles – it was first described in 1949 by Polish zoologist August Dehnel when he noticed, while measuring the skulls of shrews, that they are smaller in winter than in summer. This finding ended up being named after him as the Dehnel phenomenon.
But thanks to a recently published study in the journal Royal Society Open Science by Lucie Farková Nováková, a postdoctoral researcher at the German Max Planck Institute of Animal Behaviour, and the rest of her team, we now know that moles also number among the species of animals whose brains shrink seasonally, along with shrews, weasels and stoats. These species of animal all have an extremely high metabolism due to their small size and year-round activity, meaning they burn through energy stores in a matter of hours. This puts them on a knife edge in the deep winter months, when their metabolism approaches the upper limit of what is possible for mammals.
But the study doesn’t only add another small mammal to the list of creatures employing Dehnel's phenomenon – it also tries to shed light on what specific evolutionary pressure is behind it and what triggers it. By comparing moles from different climates, the researchers found evidence to suggest that Dehnel's phenomenon is probably driven by the seasonal temperature drop rather than food shortage alone. Shrinking an energy-intensive organ such as the brain allows the animals to reduce energy consumption and thus survive the cold weather.