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Compared to many other species, all humans have incredibly similar genomes. However, even slight variations in our genes or environments can cause us to develop traits that make us unique. These differences can manifest in ordinary ways, such as through hair color, height, or facial structure, but occasionally, a person or population develops a characteristic that distinctly sets them apart from the rest of the human race.
和其他物种相比，人类有着令人难以置信的基因组。然而，我们的基因或环境的些微改变也可能导致我们发展出与众不同的特点。这些差异一般都以普通的方式表现出来，例如头发颜色、身高、面部结构等。不过，某个或某一类人有时也会发展出截然不同地、区别于其他人类的典型特征。
10.Can't Get High Cholesterol
10.胆固醇不会增高
While most of us have to worry about limiting our intake of fried foods, bacon, eggs, or anything that we're told is on the "cholesterol-raising list" of the moment, a few people can eat all these things and more without fear. In fact, no matter what they consume, their "bad cholesterol" remains virtually non-existent.
我们大多数人都担心油炸食品如培根、鸡蛋或其他会增加胆固醇的食物的摄入量。不过有少数人可以肆无忌惮地吃，不需要担心胆固醇会因此增加。事实上，不论他们吃什么，他们的坏胆固醇并不存在。
These people were born with a genetic mutation. More specifically, they lack working copies of a gene known as PCSK9, and while it's usually unlucky to be born with a missing gene, in this case, it seems to have some positive side effects.After scientists discovered the relationship between this gene (or lack thereof) and cholesterol about 10 years ago, drug companies have worked frantically to create a pill that would block PCSK9 in other individuals. The drug is close to getting FDA approval. In early trials, patients who have taken it have experienced as much as a 75-percent reduction in their cholesterol levels.So far, scientists have only found the mutation in a handful of African Americans, and those with it have the benefit of a 90-percent reduced risk of heart disease.
这些人出生时基因发生了突变，说得更具体些，他们缺少有效的PCSK9基因对，一般来说，出生时丢失基因是件不幸的事，不过，在这种情况下，它反而产生了有益的效果。自从10年前，科学家们发现了PCSK9基因（缺失）与胆固醇之间的关系后，便开始疯狂地研究能够阻止PCSK9的药物。该药物获美国食品与药物管理局（ FDA ）批准的可能性很高。在早期的实验中，服用此药的病人的胆固醇水平减少了75%。到目前为止，科学家们只在极少数的非裔美国人中发现了这种突变。这些人患心脏疾病的风险比常人降低了90%。
9.Resistance To HIV
9.抵抗艾滋病毒
All sorts of things could wipe out the human race—asteroid strikes, nuclear annihilation, and extreme climate change, just to name a few. Perhaps the scariest threat is some type of super-virulent virus. If a disease ravages the population, only the rare few who are immune would have a chance of survival. Fortunately, we know that certain people are indeed resistant to particular diseases.
能够毁灭人类的东西可谓多矣：小行星撞击、核打击、极端气候变化，等等。不过，最恐怖的威胁要数某些类型的超级病毒。如果一种疾病即将毁灭人类，只有少数具有免疫能力的人能够幸免于难。幸运的是，我们知道某类人确实能够抵御特殊疾病。
Take HIV, for example. Some people have a genetic mutation that disables their copy of the CCR5 protein. HIV uses that protein as a doorway into human cells. So, if a person lacks CCR5, HIV can't enter their cells, and they're extremely unlikely to become infected with the disease. That being said, scientists say that people with this mutation are resistant rather than immune to HIV. A few individuals without this protein have contracted and even died from AIDS. Apparently, some unusual types of HIV have figured out how to use proteins other than CCR5 to invade cells. This type of resourcefulness is why viruses are so scary.Folks with two copies of the defective gene are most resistant to HIV. Currently, that includes only about 1 percent of Caucasians and is even more rare in other ethnicities.
就拿HIV来说，一些人发生基因突变，使他们丧失了复制CCR5蛋白的能力。CCR5蛋白是HIV进入人体细胞的门户。因此，一个缺失CCR5的人，HIV便无法进入他的细胞内，从而使得他们避免遭受感染。话虽如此，不过科学家们还表示，发生这类基因突变的人只能够抵抗HIV，而不是对其免疫。这也就是为什么有少数人尽管缺失此类蛋白，但依旧被感染甚至死于艾滋病。显然，一些特殊的HIV想通了如何利用CCR5之外的蛋白入侵细胞。这种类型的智谋正是病毒何以可怖的原因。拥有两对缺陷基因的人大多能够抵御HIV。目前，这种人在高加索人中所占比例为百分之一，在其他种族中比例更低。
8.Malaria Resistance
8.防止疟疾
Those who have an especially high resistance to malaria are carriers of another deadly disease: sickle cell anemia. Of course, no one wants the ability to dodge malaria only to die prematurely from malformed blood cells, but there is one situation where having the sickle cell gene pays off. To understand how that works, we have to explore the basics of both diseases.
这些对疟疾有超高抵御能力的人同时也是另外一种致命疾病的携带者：镰刀型红血球疾病。当然，没有人愿意为了避免疟疾而拥有这种"能力"，因为患此病的人最终平均寿命只有四十岁。为了了解它们如何工作，我们得探究这两种疾病的基本知识。
Malaria is a type of parasite carried by mosquitoes that can lead to death or at the very least make someone feel at death's door. Malaria does its dirty work by invading red blood cells and reproducing. After a couple days, new malaria parasites burst out of the inhabited blood cell, destroying it. They then invade other red blood cells. This cycle continues until the parasites are stopped through treatment, the body's defense mechanisms, or death. This process causes a loss of blood and weakens the lungs and liver. It also increases blood clotting, which can spark a coma or seizure. Sickle cell anemia causes changes in the shape and makeup of red blood cells, which makes it difficult for them to flow through the blood stream and deliver adequate levels of oxygen. However, because the blood cells are mutated, they confuse the malaria parasite, making it difficult for it to attach and infiltrate the blood cells. Consequently, those who have sickle cells are naturally protected against malaria. You can get the anti-malaria benefits without actually having sickle cells, so long as you're a carrier of the sickle cell gene. To get sickle cell anemia, a person has to inherit two copies of the mutated gene, one from each parent. If they only get one, they have enough abnormal hemoglobin to resist malaria yet will never develop full-fledged anemia.Because of its strong protection against malaria, the sickle cell trait has become highly naturally selected in areas of the world where malaria is widespread, with as much 10–40 percent of people carrying the mutation.
疟疾是一种通过蚊子传播的寄生虫传染病，每年导致的死亡人数高达上百万。疟疾通过入侵红血细胞，不断繁殖。短短几天，新的疟原虫便在所寄生的血细胞中爆发，并破坏血细胞。接着入侵其他血细胞。这个过程只有在疟原虫死亡，或者被治疗方法阻止、人体产生防御机制时才会停止。整个过程会导致大量的血亏损，肺和肝的功能也会遭到损伤。它还会增加血凝块，导致昏迷不醒和癫痫。镰刀型红血球疾病会使红血球改变形状，失去携氧能力。正因为红血球细胞产生了变异，从而能够迷惑疟原虫，让其连接、渗透红细胞变得更为困难。于是，这些患有镰刀型红血球疾病的人便能够抵御疟疾。并不是非得拥有镰刀型细胞才能防止疟疾，事实上携带镰刀型基因也能拥有此种功能。一个人只有从父母那获得两对突变基因才会患有镰刀型红血球疾病，如果他只获得了一对呢？这种情况下，他拥有的异常血红蛋白既能够防止疟疾，同时也不会患上镰刀型红血球疾病。因为具有极强的防御疟疾功效，镰刀型细胞具有很高的地域选择性，在疟疾高发地区，约有10—40%的人携带这种突变基因。
7.Tolerance For Coldness
7.耐寒能力
Inuits and other populations who live in intensely cold environments have adapted to an extreme way of life. Have these people simply learned how to survive in these environments, or are they somehow biologically different?
因纽特人及其他生活在酷寒环境之中的人们，需要适应一种极端的生活方式。这些人仅仅是简单学习如何在此种环境中生存，还是他们在生理上出于某种原因而与众不同？
Cold-dwellers have different physiological responses to low temperatures compared to those who live in milder environments. And it appears there might be at least a partial genetic component to these adaptations, because even if someone moves to a cold environment and lives there for decades, their bodies never quite reach the same level of adaptation as natives who have lived in the environment for generations. For instance, researchers have found that indigenous Siberians are better adapted to the cold even when compared to non-indigenous Russians living in the same community.People native to cold climates have higher basal metabolic rates (around 50 percent higher) than those accustomed to temperate climates. Also, they can maintain their body temperatures better without shivering and have relatively fewer sweat glands on the body and more on the face. In one study, researchers tested different races to see how their skin temperatures changed when exposed to cold. They found that Inuits were able to maintain the highest skin temperature of any group tested, followed by other Native Americans.These types of adaptations partly explain why aboriginal Australians can sleep on the ground during cold nights (without shelter or clothing) with no ill effects and why Inuits can live much of their lives in subzero temperatures.The human body is much better suited at adjusting to heat than to cold, so it's rather impressive that people manage to live at all in freezing temperatures, let alone thrive.
寒冷环境中的居住者相比较那些在温暖环境居住的人们来说，对于低温度的生理性反应有所不同。这种情况之所以发生，也许是为了适应环境而发生了一小部分遗传成分的改变。因为，即使是移居至寒冷生活环境中居住数载的人，他们身体的适应性水平，依然无法等同于那些在本环境中居住数代的人们。例如，调查者发现，虽然生活在同一个群落，但土著西伯利亚人较之非本地的俄罗斯人来说，对于寒冷的适应能力更强。土生土长于寒冷环境中的人们，比那些习惯了温带气候的人们，拥有更高的基础代谢率（大概高于百分之五十）。而且，他们能够更好的维持体温而不至于打寒战，并可以在身体上拥有相对少的汗腺，而在脸上拥有的更多。在一项研究中，调查者们测试了不同种族的人们，去观察当他们的皮肤暴露于寒冷中时，其表面温度是如何变化的。调查者发现，因纽特人在所测试的所有种族的人群中，其皮肤可以保持最高的温度，紧接着是其他本土美国人。这些类型的适应性，部分程度上解释了为什么澳大利亚土著人可以在寒冷的晚上睡在地面上（没有遮蔽物或者衣服），也不至于生病，并说明了为什么因纽特人大部分的生活都是居住在零度以下的环境。人体在调整热的方面比调整冷更加擅长，所以，令人印象十分深刻的是，人们都设法居住在寒冷的温度中，独自成长壮大。
6.Optimized For High Altitude
6.更适应高海拔环境
Most climbers who've made it to the summit of Mt. Everest wouldn't have done so without a local Sherpa guide. Amazingly, Sherpas often travel ahead of the adventurers to set ropes and ladders, just so the other climbers have a chance of making it up the steep cliffs.
如果没有当地夏尔巴人作为向导，很多人将无法成功登顶珠穆朗玛峰。夏尔巴人经常走在冒险者前面，为他们设置绳索和梯子，只有这样，这些攀登者才有机会登上陡峭的悬崖。
There's little doubt that Tibetans and Nepalese are physically superior in this high-altitude environment, yet what is it exactly that allows them to work vigorously in oxygen-depleted conditions, while ordinary folks have to struggle just to stay alive?Tibetans live at an altitude above 4,000 meters (13,000 ft) and are accustomed to breathing air that contains about 40 percent less oxygen than at sea level. Over the centuries, their bodies compensated for this low-oxygen environment by developing bigger chests and greater lung capacities, which make it possible for them to inhale more air with each breath. And, unlike lowlanders whose bodies produce more red blood cells when in low oxygen, high-altitude people have evolved to do the exact opposite—they produce fewer red blood cells. This is because while an increase in red blood cells might temporarily help a person get more oxygen to the body, it makes blood thicker over time and can lead to blood clots and other potentially deadly complications. Similarly, Sherpas have better blood flow in their brains and are overall less susceptible to altitude sickness.Even when living at lower altitudes, Tibetans still maintain these traits, and researchers have found that many of these adaptations aren't simply phenotypic variances but are genetic adaptations. One particular genetic change occurred in a stretch of DNA known as EPAS1, which codes for a regulatory protein. This protein detects oxygen and controls production of red blood cells and explains why Tibetans don't overproduce red blood cells when deprived of oxygen, like ordinary people.The Han Chinese, the lowland relatives of the Tibetans, do not share these genetic characteristics. The two groups split from each other about 3,000 years ago, which means these adaptations occurred in only about 100 generations—a relatively short time in terms of evolution.
毋庸置疑，藏族人和尼泊尔人在高海拔环境下身体十分出众。那么，到底是什么使得他们在如此缺氧的环境下精力如此旺盛？要知道，普通人在这种环境下只有喘气的分。藏人生活在4000米高的海拔，常年呼吸着氧含量比海平面约少40%的空气。几个世纪以来，他们的身体发展出宽大的胸腔，拥有更大的肺容量作为补偿。这让他们每次呼吸都能够吸入更多的空气。与居住在低海拔的人不同，低海拔地区的人身处低氧环境时身体会制造更多的红血细胞，而高海拔地区的人则进化出截然相反的功能：他们产生更少的红细胞。这是因为红细胞的增加只会暂时帮助身体获取更多的氧气，但是随着时间的推移，却会导致血液变厚，产生血凝块，以及其他致命的并发症。相似的，夏尔巴人大脑的血流量更好，这使得他们整体不易产生高原反应。当藏人居住在低海拔地区时，他们仍然保持着这种特征。研究人员发现，这种变化并不是简单的表面型改变，而是遗传性适应。一个特定的基因变化发生在一段名为EPAS1的DNA上，其编码调节蛋白质。这种蛋白质检测氧气并控制红血细胞的生产量。这就解释了为什么当藏族人身处缺氧环境时不会像正常人那样制造更多的红血细胞。生活在低海拔地区的汉人虽然是藏族人的亲属，却并没有这种基因特征。汉人和藏人大约在3000年前分开，这就意味着这种改变的发生仅仅只有100代人的时间——属于进化中时间较短的情况。
翻译：烟囱、徐杉、欧阳远丽、阿饭、孟庆润 来源：前十网
