藏人如何避免高度疾病？

2005年，俄亥俄州克利夫兰凯斯·西大学（Case Western University高血压and other maladies resulting from living at such high altitudes. They found the answer within the Tibetans' breath.

研究人员发现，藏族呼气要比居住在海平面的对照组要少得多。更重要的是，藏人的肺从其中转移了两倍的一氧化氮数量肺walls into their bloodstreams than their sea-level-dwelling counterparts'. Nitric oxide is believed to aid in the expansion of血vessels. Blood flows more easily, which allows the heart to work at a normal pace, due to the decrease in blood pressure from vessel expansion.

That means that the Tibetans' hearts can deliver more of the lower ambient oxygen available in the air to their bodies. With the dilated blood vessels, Tibetans can achieve this with less effort than a person at the same altitude whose cardiopulmonary system is used to near-sea level pressure.

这代表了人类的强烈例子不断发展适应他们的环境。居住在高海拔地区的人类已经适应了异常的大气条件，并且有理由在世界各地都可以在人类居住在类似于西藏的海拔的地方找到这一点。除了不是。

关于居住在高海拔地区的人们的第一个研究是在1890年，当时法国人弗朗索瓦·维特（Francois Viault）研究了居住在南美安第斯山脉的人们的红细胞人数。红细胞携带血红蛋白，这是携带氧气的血液的一部分。因此，Vialet理论认为安第斯山脉人的红细胞计数会高。他是对的。安第斯山脉开发了一个过程，可以补偿薄山空气中缺乏可用的氧气。但是这个特征 - 或表型- 在藏人中找不到。相反，在安第斯人中找不到藏人对一氧化氮的更高使用。

A third group, the people of the Ethiopian highlands, don't have either of these traits. In fact, the Ethiopian highlanders don't appear to have any special traits to compensate for life at higher altitudes. The characteristics of their cardiopulmonary systems -- like oxygen saturation and hemoglobin count -- are virtually identical to those found in people living at sea level.

It's possible that the Ethiopians do possess a trait that has yet to be discovered; the highlanders have only been studied once, while the Andeans have been studied for more than a century and the Tibetans for decades. But the differences that have been found between Andeans, Ethiopians and Tibetans represent human biodiversity. This is significant, because it is through diversity that a species can thrive on Earth.

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