研究表明，进化可能是人类易患心脏病的原因

研究表明，进化可能是人类易患心脏病的原因

One-third of global deaths are due to cardiovascular disease caused by atherosclerosis, when arteries are clogged with fat deposits. Although it's common for humans to experience heart attacks, the same event is rare in mammals. Now, researchers believe that they understand why.

全球三分之一的死亡是由动脉粥样硬化导致的心血管疾病引起的，动脉因脂肪沉积而堵塞。虽然人类心脏病发作很常见，但在哺乳动物中却很少见。现在，研究人员相信他们明白了其中的原因。

Risk factors for cardiovascular disease in humans can include age, hypertension, obesity, smoking, blood cholesterol and inactivity. However, in 15% of cardiovascular events caused by atherosclerosis, none of these risk factors is at hand.

人类心血管疾病的危险因素包括年龄、高血压、肥胖、吸烟、血液胆固醇和缺乏运动。然而，在15%由动脉粥样硬化引起的心血管事件中，这些危险因素都不存在。

Closely related mammals like chimpanzees living in captivity share some of the same risk factors for cardiovascular disease: hypertension, inactivity and high blood lipids.

与人类关系密切的哺乳动物，比如圈养的黑猩猩，也有与患心血管疾病的相同风险因素:高血压、缺乏运动和高血脂。

But these chimps rarely experience heart attacks. If they do, it's not due to atherosclerosis; the cause is scarring of the heart muscle, which has yet to be explained.

但这些黑猩猩很少患心脏病。即使有，也不是因为动脉粥样硬化;其原因是心肌的结疤，目前还没有得到解释。

Researchers think that there was the loss of a single gene, CMAH, in human ancestors between 2 million and 3 million years ago, leading to a higher risk of cardiovascular disease. This gene included a sialic acid sugar molecule called Neu5Gc. Apes and chimps have maintained this gene and molecule over time.

研究人员认为，200万至300万年前，人类祖先的CMAH基因缺失，导致心血管疾病的风险增加。这个基因包括一种叫做Neu5Gc的唾液酸糖分子。随着时间的推移，猿和黑猩猩一直保持着这种基因和分子。

In a new study, mice were modified to be similarly deficient in this molecule, which caused a twofold increase in atherosclerosis compared with mice who were not modified. The study was published Monday in the journal Proceedings of the National Academy of Science.

在一项新的研究中，转基因小鼠同样缺乏这种分子，与非转基因小鼠相比，这导致动脉粥样硬化增加了两倍。这项研究周一发表在《美国国家科学院院刊》杂志上。

"The increased risk appears to be driven by multiple factors, including hyperactive white cells and a tendency to diabetes in the human-like mice," said study author Dr. Ajit Varki, Distinguished Professor of Medicine and Cellular and Molecular Medicine at the University of California San Diego School of Medicine. "This may help explain why even vegetarian humans without any other obvious cardiovascular risk factors are still very prone to heart attacks and strokes, while other evolutionary relatives are not."

“这种增加的风险似乎是由多种因素造成的，包括过度活跃的白细胞和类人小鼠患糖尿病的倾向，”研究作者阿吉特·瓦尔基博士说，他是加州大学圣地亚哥医学院的医学和细胞及分子医学的杰出教授。“这可能有助于解释，为什么没有任何其他明显心血管风险因素的素食者仍然很容易患心脏病和中风，而其他进化上的近亲则不然。”

Even though humans lack this gene and the Neu5Gc molecule within it, those who regularly eat red meat are exposed to it. Consuming it as a byproduct of red meat causes the human body to react with an immune response as well as chronic inflammation.

即使人类缺少这种基因和Neu5Gc分子，那些经常吃红肉的人也会接触到这种基因。食用红肉的副产品会导致人体产生免疫反应和慢性炎症。

The modified mice in the study were fed a diet similar to that of humans who eat red meat: high in fat and rich in Neu5Gc. This caused the mice to develop an additional 2.4-fold increase in atherosclerosis.

在研究中，转基因老鼠的饮食与食用红肉的人类相似:高脂肪，富含Neu5Gc。这导致小鼠动脉粥样硬化增加了2.4倍。

"The human evolutionary loss of CMAH likely contributes to a predisposition to atherosclerosis by both intrinsic and extrinsic [dietary] factors and future studies could consider using this more human-like model," the study authors wrote.

该研究的作者写道:“人类进化过程中CMAH的缺失可能会导致动脉粥样硬化的发生，无论是内在的还是外在的(饮食)因素，未来的研究可以考虑使用这种更像人类的模型。”

The same research team has also demonstrated that modified mice fed a Neu5Gc-rich diet were more susceptible to inflammation and cancer progression, suggesting a link between certain cancers and diets rich in red meat.

该研究小组还证明，食用富含Neu5gc的食物的转基因老鼠更容易患炎症和癌症，这表明了某些癌症与食用富含红肉的食物之间存在联系。