The Western Hudson Bay polar bears are probably the most studied polar bear inhabitants within the Arctic. They’re additionally those which were most extensively filmed, photographed and marveled at, due to the tourism business that has developed across the bears in Churchill, Manitoba, Canada.
Symbols of braveness, resilience and energy, polar bears have been featured in ornamental arts for hundreds of years. At this time, they might be greatest referred to as emblems of local weather change, “charismatic victims” used to encourage folks to care about our warming Earth. However not solely does Ursus maritimus persist in our consciousness, polar bears—the biggest bear on the planet—proceed to astound us with their creativity, intelligence, persistence and physiology.
For instance, a latest evaluation of historic DNA from a 100,000-year-old polar bear has revealed that in depth hybridization between polar bears and brown bears occurred over the last heat interglacial interval within the Pleistocene, leaving a shocking quantity of polar bear ancestry within the genomes of all residing brown bears at this time.
In one other new discovering, the key to how polar bears handle to outlive and thrive in one of many world’s most punishing climates involves mild: greasy hair.
A polar bear’s cranium can train us in regards to the diversifications that assist polar bears survive within the harsh Arctic surroundings and the way the animals have advanced over time. ©Klaus Rassinger und Gerhard Cammerer, Museum Wiesbaden, Wikimedia Commons
Historical hybridization with brown bears
Though polar bears and brown bears are distinct species with placing variations in look, habits and habitats, they’re intently associated and might readily hybridize when their ranges overlap. Studies of hybrids have elevated in recent times because the local weather warms and disappearing sea ice forces polar bears onto Arctic coasts, whereas brown bears broaden their vary northward.
Earlier research of historic DNA have proven that admixture has occurred in sure populations of brown bears no less than 4 totally different instances between about 15,000 and 25,000 years in the past. In all instances, the route of gene move was from polar bears into brown bears. These blended people, in the event that they survived, did in order brown bears; maybe as a result of they’d have had issue looking efficiently on the ocean ice in the event that they weren’t utterly white. Polar bears have at all times been a small inhabitants with not a lot genetic variety.
In 2009, the cranium of a juvenile polar bear—nicknamed “Bruno” (though DNA evaluation later confirmed it to be feminine)—was discovered on the coast of the Beaufort Sea in Arctic Alaska. An evaluation by scientists from the College of California, Santa Cruz, established that Bruno belonged to a polar bear inhabitants that was ancestral to residing polar bears. Discovering Bruno’s cranium was serendipitous. Since polar bears spend most of their lives at sea, coming throughout any polar bear stays is extraordinarily uncommon. Bruno’s is the one historic polar bear cranium that’s ever been recorded—and the one historic polar bear bone recognized from North America.
Polar bear ancestry accounts for as a lot as 10% of the genomes of brown bears residing at this time, indicating that historic hybridization between the 2 species occurred, with gene move primarily transferring from polar bears to brown bears.
In some unspecified time in the future, most likely round 125,000 years in the past, the polar bear lineage resulting in Bruno and the brown bear lineage resulting in all residing brown bears crossed paths and hybridized. On account of accessibility to Bruno’s paleogenome, the California researchers realized that polar bear ancestry accounts for as a lot as 10% of the genomes of brown bears residing at this time. Their outcomes have been revealed in June 2022 within the journal Nature Ecology & Evolution.
This examine did discover some proof of attainable gene move from brown bears into Bruno’s lineage, however the absence of admixture in polar bears at this time helps the concept brown bear ancestry reduces a bear’s health for all times as a polar bear. After diverging from brown bears about 500,000 years in the past, polar bears advanced into extremely specialised hunters of marine mammals on the Arctic sea ice. Brown bears, in distinction, are generalists ranging extensively throughout Asia, Europe and North America.
Climatic shifts which have introduced polar bears and brown bears collectively prior to now embody glacial intervals when sea ice was extra in depth, permitting polar bears to combine with brown bears in southeast Alaska, the Kuril Islands within the Russian Far East and even Eire. The brown bears in these areas (now extinct in Eire) acquired further polar bear genes on prime of the traditional admixture revealed by Bruno’s genome. As for what brown bears may need gained from their polar bear ancestry, scientists can solely speculate. It’s attainable that brown bears received one thing cool from polar bears, however nobody is aware of for positive—but.
In contrast to polar bears which can be extremely specialised hunters of marine mammals on the Arctic sea ice, brown bears are generalists that vary extensively throughout Asia, Europe and North America. This bear is munching on blueberries.
Bruno lived throughout a time of adjusting local weather after the height of a heat interglacial interval when temperatures and sea ranges have been significantly larger than they’re now. Comparable situations may be anticipated sooner or later due to speedy local weather change, pushed by the burning of fossil fuels and different human actions. As Arctic sea ice declines, many polar bear populations are already struggling to outlive. If the speedy, unnatural and extreme human-caused warming of the Arctic we’re documenting at this time continues unabated, it’s unsure whether or not polar bears could have a sea-ice habitat to return to and survive genetically, say the scientists.
Nevertheless, we shouldn’t be stunned to see gene move occurring between what we consider as totally different species taking place once more at this time because the local weather modifications and brown bears and polar bears overlap and encounter one another once more within the wild. Understanding how previous modifications within the local weather drove interactions between organisms is crucial to predicting how present modifications will create new admixtures, enhance illness transmission, or impression pure assets or society, conclude the scientists.
Fur with anti-icing properties
After some “polar sleuthing,” which concerned scrutiny of hair collected from six polar bears within the wild, scientists from Trinity Faculty Dublin’s College of Chemistry and AMBER Analysis Middle in Eire and the College of Bergen in Norway discovered that hair sebum (or grease)—which is made up of ldl cholesterol, diacylglycerols and fatty acids—makes it very onerous for ice to connect to polar bears’ fur. These findings have been revealed within the worldwide journal Science Advances in January 2025.
Sebum, fatty lubricant matter secreted by sebaceous glands of the pores and skin, present in polar bear fur is the important thing part that offers the bears their anti-icing properties, which come in useful when looking seals on ice platforms.
To conduct this examine, the researchers measured ice adhesion energy, which is a helpful measure of how effectively ice sticks to fur; hydrophobicity, which dictates whether or not water may be shed earlier than it freezes; and freezing delay time, which merely exhibits how lengthy it takes for a drop of water to freeze at sure temperatures on a given floor. They then in contrast the efficiency of the polar bear hair with that of human hair and two varieties of specialist, human-made “ski skins.”
The sebum rapidly jumped out as being the important thing part giving the anti-icing impact, for the reason that adhesion energy was significantly impacted when the hair was washed. When washed and the grease largely faraway from it, polar bear hair carried out equally to human hair, to which ice sticks simply whether or not it’s washed or greasy. In distinction, unwashed, greasy polar bear hair made it a lot more durable for ice to stay.
That discovering led the staff to carry out an in depth chemical evaluation of polar bear sebum. In addition to figuring out its key parts, the scientists have been stunned to search out squalene was absent. This fatty metabolite is current in human hair and within the hair of different aquatic animals, akin to sea otters, which suggests its absence in polar bear hair is essential from an anti-icing perspective.
Regardless of spending in depth intervals in water at subzero temperatures, polar bears don’t undergo from ice accumulation. Their “fur grease” gives a pure route for simply shedding ice.
This work not solely represents the primary examine of the composition of polar bear fur sebum, nevertheless it additionally resolves the query of why polar bears don’t undergo from ice accumulation. Regardless of having thick layers of insulating blubber and fur and spending in depth intervals in water at subzero temperatures, polar bears have a pure route of their fur for simply shedding ice when it types.
These pure lipid coatings produced by polar bears will assist us develop new, extra sustainable, anti-icing coatings which will exchange problematic eternally chemical substances, akin to PFAS, which were beforehand used. They might even have a set of unrelated functions, with an identical concoction of artificially-made sebum promising to be helpful as an anti-ice floor coating or in next-gen ski skins utilized by skiers and snowboarders.
This isn’t the primary time that animals residing in polar habitats have emerged as a supply of inspiration for the event of recent anti-icing supplies. For instance, it was not too long ago found that the hierarchical construction of Gentoo penguin feathers provides the birds anti-icing properties.
The hierarchical construction of Gentoo penguin feathers afford the birds anti-icing properties that depend on feather construction moderately than on a preening oil coating.
These fascinating discoveries additionally assist us higher perceive the ecology of each polar bears and native Inuit populations. One of many polar bear’s essential looking methods is “nonetheless looking,” the place the animal stays immobile beside a respiratory gap on sea ice ready for seals to floor. Nonetheless looking regularly develops into an “aquatic stalk,” with the polar bear utilizing its hind paws to slip into the water to pursue its prey; and the decrease the ice adhesion, the much less noise generated and the quicker and quieter the slide.
Inuit folks optimize their looking methods to imitate the polar bear technique of nonetheless looking. Inuit looking stools are typically shod with polar bear fur on the ft to keep away from noise when transferring on the ice. And other people typically put on “polar bear trousers,” making certain all the contact space with the ice is roofed in low-ice-adhesion polar bear fur for optimum noise discount.
Notably, the normal Inuit preparation technique protects the sebum on the fur by making certain the hair-covered aspect of the pores and skin will not be washed. That is in contrast to, for instance, a fox pores and skin, which might historically be cleaned by rubbing the hair aspect with soapstone or dry clay.
Inuit folks mannequin their looking methods on the polar bear technique of “nonetheless looking.” They often put on trousers comprised of polar bear fur, making certain that their contact space with the ice is roofed in a low-ice-adhesion materials that can be optimum for noise discount.
Polar bear inhabitants declines as a consequence of “power deficit”
Sadly, such enjoyable and informative discoveries about polar bears might not go on eternally. In one other January 2025 examine, this time revealed within the journal Science, researchers from the College of Toronto Scarborough developed a mannequin that demonstrates that inhabitants decline in polar bears is the results of the bears not getting sufficient power, and that’s as a consequence of a scarcity of meals attributable to shorter looking seasons on dwindling sea ice. A lack of sea ice means bears spend much less time looking seals and extra time fasting on land, which negatively impacts the bears’ power steadiness, resulting in lowered copy and cub survival and, in the end, inhabitants decline.
The “bio-energetic” mannequin developed by the researchers tracks the quantity of power the bears are at present getting from looking seals and the quantity of power they should develop and reproduce. What’s distinctive in regards to the mannequin is that it follows the complete life cycle of particular person polar bears—from cub to maturity—and compares it to 4 a long time of monitoring knowledge from the Western Hudson Bay polar bear inhabitants between 1979 and 2021. Throughout this era, the polar bear inhabitants on this area has declined by practically 50%. The monitoring knowledge exhibits that the typical measurement of polar bears can be in decline. The physique mass of grownup females has dropped by 86 kilos and that of one-year-old cubs by 47 kilos over a 37-year interval.
The researchers’ mannequin gives an in depth match to the monitoring knowledge, which means it gives an correct evaluation of what’s taking place and can proceed to occur to the polar bear inhabitants if it retains experiencing sea-ice loss and a better period of time in power deficit. The mannequin, nevertheless, goes one step additional than saying there’s a correlation between declining sea ice and inhabitants decline. It gives a mechanism that exhibits what occurs when there may be much less ice, much less feeding time and fewer power total. When the numbers are run, there’s a close to one-to-one match to what’s seen in actual life.
Polar bear cubs face the brunt of climate-induced challenges. Shorter looking intervals trigger moms to supply much less milk, which jeopardizes their younger ones’ survival. Moms now are additionally having fewer cubs.
Sadly, cubs face the brunt of those climate-induced challenges. Shorter looking intervals lead to moms producing much less milk, which jeopardizes cub survival. The cubs face lowered survival charges throughout their first fasting interval in the event that they fail to achieve sufficient weight.
Moms are additionally having fewer cubs. Monitoring knowledge exhibits cub litter sizes have dropped 11% in comparison with nearly 40 years in the past, and moms are preserving their cubs longer as a result of they aren’t robust sufficient to stay on their very own. And, merely put, the survival of cubs straight impacts the survival of the inhabitants.
Western Hudson Bay has lengthy been thought of a bellwether for polar bear populations globally; and because the Arctic warms at a charge 4 instances quicker than the worldwide common, the researchers warn of comparable declines in different polar bear populations. This mannequin principally describes their future, they are saying.
Many Inuit hunters take into account polar bears to be probably the most clever animal within the Arctic. For the remainder of us, polar bears characterize braveness, resilience and energy. The saying is trite however true: polar bears are on skinny ice. Let’s not lose them on our watch.
Polar bear proficiencies and product concepts
An Arctic icon, polar bears have additionally performed roles in artwork, conservation and politics. We’re fortunate to have them nonetheless amongst us. Bruno’s historic cranium has given us insights not solely into present-day polar bear physiology however that of all residing brown bears. And at this time’s polar bears have offered inspiration for the creation of recent merchandise for anti-icing and higher traction on ice and snow.
However the warming of the Earth that our actions have induced may spell the tip for polar bears. Let’s not lose them now—on our watch.
Right here’s to discovering your true locations and pure habitats,
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