Winter is officially here in the northern hemisphere and for a bunch of us that means some cold weather.

So it's the perfect time for news about hibernating animals and some huge penguins. During the winter you and I can throw on an extra layer or crank up the heat.

But some animals survive frigid temperatures by hibernating. Hibernation is a kind of whole body slow down where animals lower their metabolisms and just chill for a while literally and their body temperatures fall sometimes to below freezing I don't know about you, but to me that sounds really unpleasant. But how do hibernators handle it?

Well, on Tuesday, biologists at Yale announced in the journal Cell Reports that they've discovered part of the secret behind this ability to withstand the cold the team worked with a few rodents to figure out what's going on Some of them hibernate like the Syrian hamster in the 13 lined ground squirrel which is named for its many stripes And others don't like lab mice. First the researchers tested the animal's temperature preferences by putting them in a chamber with two temperature controlled plates and measuring the time spent on each one one plate was a balmy 30 degrees while the second was colder and varied sometimes getting as low as freezing. For the most part the mice stayed glued to the warm plate while the two hibernating species didn't really care until the second plate got pretty cold about five or ten degrees.

This nonchalance was very similar to mice that were genetically engineered to be missing a protein known as TRMP8 suggesting that the protein might be able to explain some things TRMP8 is an ion channel in neurons that opens up in response to cold, letting ions rush in so the cells transmit a signal to the brain and spinal cord. The channel also responds to menthol, that molecule from minty oils, and a synthetic super cooling chemical called icilin. Humans use a version of this receptor to sense cold too.

Biologists thought the hibernators might have fewer of these receptors which would explain why they didn't respond as much to cold. The squirrels and hamsters had just as many as the mice. Instead the receptors themselves were less sensitive to cold.

Neurons from each of the species responded the same to icilin which means they do work But the hibernator's neurons responded much less to the same amount of cold additional experiments revealed that most of the difference in temperature sensitivity came from just 6 amino acids in the receptor protein. While the results don't explain why ground squirrels and hamsters start to get chilly below about 10 degrees it's one of the few times scientists have been able to pin down a molecular adaptation for hibernation. Last week we also learned a lot about penguin evolution.

Paleontologists in New Zealand reported the discovery of a new species of ancient penguin that lived some fifty seven million years ago and was the size of a refrigerator you heard that right. A refrigerator, or like a tall-ish person Based on the size of the fossilized femur. Scientists estimate these giant penguins were 1.77 meters tall and about a hundred kilograms Researchers named the species kumimanu biceae based in part on the Maori words for "bird" and "large mythological" monster Today the largest penguins are emperor penguins which are pretty big, but they pale in comparison they're full half metre shorter and less than half the weight.

Tens of millions of years ago giant penguins were actually the norm paleontologists know of at least nine other species dug up from places like Antarctica New Zealand and Peru. This latest one isn't even the biggest. Although that even taller bird height is based on just two bones.

The find was described in Nature communications and includes vertebrae, wing and leg bones. And what stands out is that it's so old and different from other giant penguins. A detailed comparison of the fossils puts this new bird on its own branch in the family tree living at least five million years before most of the others and that time gap suggests that penguins evolved gigantism more than once.

Not only that but most paleontologists pegged the penguin origins story to the mass extinction 65 million years ago that killed the dinosaurs. That event eliminated the big carnivorous reptiles in the ocean creating an opportunity for seabirds that were divers rather than fliers. The researchers guessed that once the birds didn't need to lift off anymore, Packing on weight might have been helpful for diving or competing for breeding grounds.

But researchers hadn't expected such extreme sizes like kumimanu just ten million years after that ecological niche opened up Even with that surprising suggestion the bigger question might be why giant penguins aren't waddling around today. The leading hypothesis is that marine mammals like whales and seals took over although scientists aren't clear on how that happened. By the end of the Maya scene earth wasn't home to giant species anymore so the penguins we know and love today are the smaller cuddly or kind.

Oh, I still wouldn't cuddle with an emperor penguin. Thanks for watching this episode of SciShow news. If you like that second story and you want to learn more about ancient animals or all kinds of paleontological science you can check out our sister channel Eons at youtube.com/eons