Meet the mammals that eat away their own brains - The Washington Post

To rapidly lick the puzzle successful Dina Dechmann’s lab, the shrew didn’t conscionable request to larn wherever its repast was hidden. Something other astounding happened successful its head. It had to regrow its ain brain.

“It’s a brainsick animal,” said Dechmann, a behavioral ecologist astatine the Max Planck Institute of Animal Behavior successful Germany. “We tin larn a batch from the shrews.”

To hole for the depths of wintertime erstwhile nutrient is scarce, galore animals dilatory down, slumber done the acold oregon migrate to warmer locales.

Not the communal shrew. To past the colder months, the carnal eats distant astatine its ain brain, reducing the organ by arsenic overmuch arsenic a fourth, lone to regrow overmuch of encephalon substance successful the spring.

The process of shrinking and expanding the encephalon and different organs with seasons — dubbed Dehnel’s improvement — allows animals to trim calorie-consuming insubstantial erstwhile temperatures drop. Researchers person discovered seasonal shrinkage successful the skulls of different small, high-metabolism mammals, including weasels and, most recently, moles.

The shrew’s unthinkable shrinking encephalon is much than conscionable a biologic curiosity. Understanding however these animals are capable to reconstruct their encephalon powerfulness whitethorn assistance doctors dainty Alzheimer’s, aggregate sclerosis and different neurodegenerative diseases successful humans.

“In the beginning, I couldn’t rather grasp it,” said John Dirk Nieland, an subordinate prof of wellness subject and exertion who is present researching drugs designed to mimic shrews’ brain-altering chemistry successful humans.

“It’s truly astonishing the mode they respond and the mode they respond,” helium added.

For decades, fewer scientists grasped the implications of August Dehnel’s 1949 discovery.

Born successful Warsaw, Dehnel spent his aboriginal vocation studying vertebrate eggs earlier the Nazi penetration of Poland interrupted his enactment connected Europe’s beavers and different mammals.

The young zoologist served successful the Polish army, though helium remained devoted to his world enactment during the war. Captured by the Germans, helium gave biology lectures astatine a prisoner-of-war camp.

Back successful the laboratory aft the war, helium noticed the skulls of shrews collected from the Białowieza Forest astatine the borderline of Poland and Belarus contracted and expanded with the seasons.

The high-metabolism mammal pursues insects, spiders, slugs and worms seemingly nonstop to survive. Ranging from the Scottish highlands to the Siberian tundra, it squeaks astatine pitches beyond quality hearing, listening for reverberations to navigate underground.

Unlike cervid oregon bears, shrews are excessively tiny to migrate and excessively hyper to hibernate erstwhile wintertime arrives. They unrecorded accelerated and dice young, with an mean beingness span of a small much than a year. “Their metabolism isn’t acceptable up for slowing down similar that,” Dechmann said.

That makes the jittery creatures awfully challenging to survey successful captivity.

The communal shrew is 1 of the fewer mammals with a venomous bite, and it emits a nasty odor perchance to deter cats and different predators. To acclimate the shrews to the seasons, the squad keeps its cages outdoors.

Dehnel himself struggled to cage and breed shrews, though helium yet succeeded. And their metabolism is truthful precocious that Dechmann and her colleagues find it hard to sedate them for scans.

“We cannot get them to sleep,” she said. “It seems astir similar a knockout authorities is not built successful due to the fact that they can’t spend to go unconscious due to the fact that they’ll simply starve.”

“They’re small bastards,” she added.

Shrews’ unorthodox strategy of reducing their encephalon powerfulness whitethorn assistance them prevention connected vigor during the winter, but it comes astatine a cost.

In a bid of experiments involving uncovering nutrient successful a sandbox, larger-brained shrews successful the summertime outperformed their smaller-brained counterparts successful the winter, Dechmann’s squad found.

“It’s a compromise,” she said. “You marque your encephalon smaller, you prevention energy, but you go — I don’t privation to accidental stupid, but you go little bully astatine solving definite learning tasks.”

But it’s what happens adjacent that’s remarkable: In the spring, their brains turn back, and their quality to lick laboratory puzzles appears to return, too. The squad is present investigating the shrew’s quality to navigate a labyrinth made of LEGO pieces.

“The quality of the shrew is that, yes, they shrink the brain, but what we spot besides is that successful the spring, they tin commencement increasing the brain,” said Nieland, who besides co-founded a biotech institution named 2N Pharma.

The conception that, for immoderate animals, a smaller encephalon is simply a amended 1 is simply a hard thought for galore radical to accept, Dechmann said. She and colleagues received hatred message aft publishing a survey showing immoderate bats evolved smaller brains to alert faster. Their insubstantial was titled “Bigger is not ever better.”

“People astatine the clip did not privation to judge that the encephalon would get smaller,” she said. “We person a ample encephalon and that means we’re much intelligent.”

Figuring retired however precisely shrews propulsion this disconnected is the adjacent step. Dechmann and Nieland — unneurotic with Liliana M. Dávalos, an evolutionary biologist astatine Stony Brook University successful New York — received a assistance from the French nonprofit Human Frontier Science Program to money their shrew research.

For one, the shrew’s encephalon doesn’t regrow uniformly. The hippocampus expands backmost to normal, for instance, portion the neocortex does not. Both of those parts of the encephalon assistance with memory.

And it’s the lipid-rich achromatic substance strewn passim the encephalon that appears to beryllium disappearing, suggesting the tiny mammal’s assemblage whitethorn beryllium consuming portions of its ain encephalon to marque it done the winter.

The deterioration of achromatic matter, which helps relay accusation successful the brain, is simply a grounds of aggregate sclerosis and different neurodegenerative illnesses.

Researchers are present searching for the proteins oregon different triggers liable for the shrinkage and regrowth successful the shrews’ noggins. “We are acold from applied results,” Dechmann cautioned, though Nieland’s institution is moving connected 1 cause close now.

If those chemicals are found, Nieland said, “we could possibly usage these pathways besides to dainty encephalon diseases.”

For Dávalos, uncovering specified an astonishing quality successful an carnal close nether European gardeners’ noses is singular successful and of itself. The find suggests determination is truthful overmuch much to find successful rainforests successful the Amazon, Congo and elsewhere.

“How galore centuries person radical been studying the European fauna?” she said. “And however galore thousands and thousands of scientists person been looking and they hadn’t seen this?”

“Think astir each the astonishing things that are retired determination hidden due to the fact that we person ne'er looked.”