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2014-01-09    来源:网络    【      美国外教 在线口语培训

Science and Technology 科技

Healthy living 健康生活

Mind and body 身与心

The reason loneliness could be bad for your health

SCIENCE has many uses, but it doesn't often produce handy pick-up lines. Recent work on the genetics of disease, however, suggest a way of opening a conversation with that solitary attractive stranger in a bar: loneliness can make you ill.

Lonely people, it seems, are at greater risk than the gregarious of developing illnesses associated with chronic inflammation, such as heart disease and certain cancers. According to a paper published last year in the Public Library of Science, Medicine, the effect on mortality of loneliness is comparable with that of smoking and drinking. It examined, and combined the results of, 148 previous studies that followed some 300,000 individuals for an average period of 7.5 years each, and controlled for factors such as age and pre-existing illness. It concluded that, over such a period, a gregarious person has a 50% better chance of surviving than a lonely one.

Steven Cole of the University of California, Los Angeles, thinks he may know why this is so. He told the AAAS meeting in Washington, DC, about his work studying the expression of genes in lonely people. Dr Cole harvested samples of white blood cells from both lonely and gregarious people. He then analyzed the activity of their genes, as measured by the production of a substance called messenger RNA. This molecule carries instructions from the genes telling a cell which proteins to make. The level of messenger RNA from most genes was the same in both types of people. There were several dozen genes, however, that were less active in the lonely, and several dozen others that were more active. Moreover, both the less active and the more active gene types came from a small number of functional groups.
加州大学洛杉矶分校的Steven Cole认为他可能知道这是为什么。他在华盛顿特区举办的美国科学促进会大会上展示了他对孤独的人的基因表达所做的研究。Cole博士收集了孤独之人和爱交际之人的白细胞样品。然后他分析了他们基因的活性——靠测量信使RNA的多少。这种分子携带着基因上的指令,告诉细胞合成那类蛋白质。在这两种人中,大多数基因的信使RNA的水平是一样的。然而有些基因在孤独之人中活力较弱,同时另外一些基因却活力较高。而且,无论是活力较高的基因还是活力较低的基因都来自少数功能群。

Broadly speaking, the genes less active in the lonely were those involved in staving off viral infections. Those that were more active were involved in protecting against bacteria. Dr Cole suspects this could help explain not only why the lonely are iller, but how, in evolutionary terms, this odd state of affairs has come about. For inflammation is an antibacterial response.

The crucial bit of the puzzle is that viruses have to be caught from another infected individual and they are usually species-specific. Bacteria, in contrast, often just lurk in the environment (like tetanus), and may thrive on many hosts (as does bubonic plague, for example). The gregarious are therefore at greater risk than the lonely of catching viruses, and Dr Cole thus suggests that past evolution has created a mechanism (the details of which remain unclear) which causes white cells to respond appropriately. Conversely, the lonely are better off ramping up their protection against bacterial infection, which is a bigger relative risk to them.

What Dr Cole seems to have revealed, then, is a mechanism by which the environment (in this case the social environment) reaches inside a person's body and tweaks its genome so that it responds appropriately. It is not that the lonely and the gregarious are genetically different from each other. Rather, their genes are regulated differently, according to how sociable an individual is. Dr Cole thinks this regulation is part of a wider mechanism that tunes individuals to the circumstances they find themselves in. Where it goes wrong is when loneliness becomes chronic, and the inflammatory response becomes chronic at the same time.

Before civilization intervened, such chronic loneliness would have been so rare (because isolated individuals are so vulnerable to predation) that evolution would have ignored it. Now, paradoxically, the large population that civilization makes possible means loneliness is commonplace—and with it consequences that natural selection, which is blind to the future, has not yet had time to deal with.

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