英语听力文摘 English Digest 602、抑郁可能对进化有好处

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　　Some scientists think they may have the answer. Depression may have an evolutionary³ benefit. It may improve one’s chances of fighting off infection.

 

　　Scientists have known that depressed⁴ people display an immunoactive condition known as inflammation, even when they are not infected. For several years they have been finding that genes⁵ linked to depression also affect the function of the immune system. Stress, which can lead to depression, also modifies the immune system. These findings suggested that depression was somehow linked to the body’s ability to fight disease.

 

　　Some scientists now propose that depression might have had an evolutionary advantage in the days before modern medicine and antibiotics⁶. Infection was a major cause of death in early human history. Surviving those infections determined⁷ which genes were passed to the next generation.

　　They suspect that depression helped people, especially children, survive infection. Fatigue⁸ leads to inactivity and less social contact which helps keep infection from spreading. Shunning⁹ food helps avoid food sharing which can also spread infection. Sleeplessness¹⁰, which is associated with both depression and immune system activation¹¹, may have been a mechanism¹² to keep a person alert to fight off predators¹³ after injury.

 

　　If scientists are correct about this link, it could lead to new treatments for depression. They are interested in drugs that treat conditions where the immune system attacks the person’s own body, known as auto¹⁴ immune diseases. It is possible that medications known to treat auto immune disease may be successful in treating depression also.

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