Polar bears are being increasingly threatened by the effects of climate change, but their disappearance could have far-reaching consequences. They are uniquely adapted to the extreme conditions of the Arctic Circle, where temperatures can reach −40°C. One reason for this is that they have up to 11 centimetres of fat underneath their skin. Humans with comparative levels of adipose tissue would be considered obese and would be likely to suffer from diabetes and heart disease. Yet the polar bear experiences no such consequences.

北极熊的数量正因为气候的改变日益受到威胁它们的消失可能会产生深远的影响。北极熊们是唯一能够适应恶劣的北极环境(极端气温可达零下40度)的动物。其中之一的原因就是因为它们的皮肤之下有厚达11厘米的脂肪层。如果人类拥有类似脂肪组织会被认为是过度肥胖，并可能遭受糖尿病和心脏病的折磨。但是北极熊不会出现以上的问题。

在2014年的研究中，Shi Ping Liu和他的同事们解答了这一谜题。他们比较了北极熊和(生活在温暖气候中的北极熊的近亲)棕熊的基因。这让他们能够确定究竟是哪个基因片段让北极熊能够在地球上最严酷的环境条件下生存。Liu和他的同事们发现，北极熊有一种被称为APoB的基因段。它可以减少低密度脂肪蛋白的水平(LDLS)-这是一种有害的胆固醇。这种基因段的变异出现在人类中的话，会提升患上心脏病的风险。因此，北极熊可能是非常重要的研究模板，对于研究和理解人类心脏病有着重要意义。

A 2014 study by Shi Ping Liu and colleagues sheds light on this mystery. They compared the genetic structure of polar bears with that of their closest relatives from a warmer climate, the brown bears. This allowed them to determine the genes that have allowed polar bears to survive in one of the toughest environments on Earth. Liu and his colleagues found the polar bears had a gene known as APoB, which reduces levels of low-density lipoproteins (LDLs) – a form of 'bad' cholesterol. In humans, mutations of this gene are associated with increased risk of heart disease. Polar bears may therefore be an important study model to understand heart disease in humans.

北极熊的基因图谱中也可能提供另一项特别影响着老年人的疾病-骨质疏松-的解决方案。这是一种骨密度变低的疾病，通常是由于缺乏锻炼，钙摄入量减少或者食物短缺造成的。骨骼组织是会不断重塑的，这就意味着它要么增加要么减少具体取决于人们的营养状况以及骨头所承担的压力。然而，雌性北极熊每次怀孕的时候都会经历极端状况。一旦秋天来临，这些雌性会在积雪中挖出供怀孕时使用的洞穴，然后整个冬天都会待在里面，无论是产崽前还是产崽后。这一过程会导致长达六个月的禁食，在这期间雌性北极熊为了保证自己和幼崽的存活，会不断消耗自己的钙和热量储备。尽管如此，它们的骨骼依然强壮紧密。

2008的时候，生理学家Alanda Lennox和AllenGoodship于解释了这一矛盾现象。他们发现怀孕的北极熊能够在开始建造兽穴之前提升自己的骨骼密度。此外，六个月后，当它们带着幼崽一起从洞穴中出来的时候，没有任何证据表明，他们的骨骼密度有明显下降。冬眠的棕熊并不具备这种能力，因此他们必须在接下来的春天进行大量的骨骼重塑。如果我们能够理解北极熊骨骼重塑的机制，许多卧床不起的人类，甚至是宇航员都能够从中受益。

The genome of the polar bear may also provide the solution for another condition, one that particularly affects our older generation: osteoporosis. This is a disease where bones show reduced density, usually caused by insufficient exercise, reduced calcium intake or food starvation. Bone tissue is constantly being remodelled, meaning that bone is added or removed, depending on nutrient availability and the stress that the bone is under. Female polar bears, however, undergo extreme conditions during every pregnancy. Once autumn comes around, these females will dig maternity dens in the snow and will remain there throughout the winter, both before and after the birth of their cubs. This process results in about six months of fasting, where the female bears have to keep themselves and their cubs alive, depleting their own calcium and calorie reserves. Despite this, their bones remain strong and dense.

北极熊对于人类医疗的积极影响当然是我们采取保护行动的重要原因，但这不应该是唯一的因素。我们总是倾向于保护我们认为聪明或者拥有情感的动物，如大象和灵长类动物。相比之下熊在很多情况下被认为是愚蠢的，甚至是凶残的。然而，关于熊的轶事证据质疑了以上这些假设，证明了北极熊其实拥有很好的解决问题的能力。大阪Tennoji动物园的一只叫做GoGo的熊雄被观察到利用工具来操控自己的生活环境。他多次用一根树枝取下那些挂在自己够不着的地方的肉。虽然不像GoGo那么明显，但是问题解决能力也同样能够在野生北极熊身上观察到。一只雄性北极熊在计算好移动线路后，助跑跳上油桶尝试接近站在四米高的平台上的摄影师。

在其他研究中，如Alison Ames在2008年所做的研究中发现北极熊展现出了故意性和目的操控性。例如，Ames观察到，北极熊会将物品先堆叠起来，然后再弄翻它们，似乎是在进行一场游戏。这项研究表明，北极熊能够做出经过思考的行为。这些例子暗示了，熊拥有比人们之前认为的更强的创造力和问题解决能力。

Physiologists Alanda Lennox and Allen Goodship found an explanation for this paradox in 2008. They discovered that pregnant bears were able to increase the density of their bones before they started to build their dens. In addition, six months later, when they finally emerged from the den with their cubs, there was no evidence of significant loss of bone density. Hibernating brown bears do not have this capacity and must therefore resort to major bone reformation in the following spring. If the mechanism of bone remodelling in polar bears can be understood, many bedridden humans, and even astronauts, could potentially benefit.

至于情感，虽然证据再一次只是传闻性质的，但当它们错过捕杀机会的时候，许多熊都被看到过出于沮丧而击打冰面或者雪地。此外，北极熊能够与其他物种形成非同寻常的关系，包括与在北极的雪橇犬玩耍。出乎意料的是，一头由人类养大的、被叫做Agee的北极与其主人Mark Dumas的关系是如此亲密，以至于他们可以一起游泳。这一点之所以让人震惊，是因为北极熊会在荒野中袭击人类是出了名的。

如果气候变化将导致北极熊灭绝，这不仅意味着人类医疗发展突破的可能性彻底消失，更重要的是，我们将失去一种智慧的、雄壮的动物。

The medical benefits of the polar bear for humanity certainly have their importance in our conservation efforts, but these should not be the only factors taken into consideration. We tend to want to protect animals we think are intelligent and possess emotions, such as elephants and primates. Bears, on the other hand, seem to be perceived as stupid and in many cases violent. And yet anecdotal evidence from the field challenges those assumptions, suggesting for example that polar bears have good problem-solving abilities. A male bear called GoGo in Tennoji Zoo, Osaka, has even been observed making use of a tool to manipulate his environment. The bear used a tree branch on multiple occasions to dislodge a piece of meat hung out of his reach. Problem-solving ability has also been witnessed in wild polar bears, although not as obviously as with GoGo. A calculated move by a male bear involved running and jumping onto barrels in an attempt to get to a photographer standing on a platform four metres high.

In other studies, such as one by Alison Ames in 2008, polar bears showed deliberate and focussed manipulation. For example, Ames observed bears putting objects in piles and then knocking them over in what appeared to be a game. The study demonstrates that bears are capable of agile and thought-out behaviours. These examples suggest bears have greater creativity and problem-solving abilities than previously thought.

As for emotions, while the evidence is once again anecdotal, many bears have been seen to hit out at ice and snow – seemingly out of frustration – when they have just missed out on a kill. Moreover, polar bears can form unusual relationships with other species, including playing with the dogs used to pull sleds in the Arctic. Remarkably, one hand-raised polar bear called Agee has formed a close relationship with her owner Mark Dumas to the point where they even swim together. This is even more astonishing since polar bears are known to actively hunt humans in the wild.

If climate change were to lead to their extinction, this would mean the loss not only of potential breakthroughs in human medicine, but more importantly, the disappearance of an intelligent, majestic animal.