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詼諧的語(yǔ)言，生動(dòng)的內(nèi)容一分鐘快速掌握科技最新動(dòng)態(tài)

本期節(jié)目音頻下載

How Its Internal Clock Is Read, Knows Reindeer

Humans are pegged to a 24-hour cycle. We're locked into it not just by day and night—there's the master timepiece in the brain called the circadian clock. But it doesn't make sense to live by a 24-hour clock in the Arctic, where it's dark or light for months at time. The solution? Lose the daily clock. Which is exactly what reindeer seem to have done, according to a study in Current Biology.

人類被限制在24小時(shí)的循環(huán)內(nèi)，不僅僅是被日夜限制其中，大腦中還有一種叫晝夜節(jié)律鐘的計(jì)時(shí)器約束著我們。可在晝夜為好幾個(gè)月的北極圈里，按照24小時(shí)來(lái)起居就沒(méi)什么意義了。有什么解決辦法嗎？有，就是拋棄白天的鐘。據(jù)《當(dāng)代生物學(xué)》的一篇研究看來(lái)，馴鹿就是一直這么做的。

Reindeer don't sleep eight hours like we do, and there's no obvious 24-hour pattern to their lives. They just chomp on tundra, nap a few hours and feast again. But they still need to know when to mate, pack on fat or thicken their coats. So they probably rely on an annual clock instead, set by the hormone melatonin.

馴鹿不像我們要睡足八小時(shí)，起居活動(dòng)也沒(méi)有明顯的24小時(shí)規(guī)律。它們只是在苔原上大嚼特嚼，睡上幾小時(shí)，接著再吃。即使如此它們也還是得了解何時(shí)交配、儲(chǔ)存脂肪或是增加皮毛，因此它們依賴的可能是由荷爾蒙褪黑素調(diào)節(jié)的年鐘。

In humans melatonin levels rise at night, in response to darkness and cues from the circadian clock. In reindeer, even if they're missing a circadian clock, melatonin levels still spike when it's dark and drop when it's light, making the equinoxes an ideal time to synchronize their annual clocks.

拿人體來(lái)說(shuō)，由于對(duì)黑暗作出反應(yīng)并受晝夜節(jié)律鐘的影響，褪黑素值會(huì)在晚上升高。即使缺少晝夜節(jié)律鐘，馴鹿的褪黑素值仍會(huì)在黑暗時(shí)達(dá)到頂峰，光亮?xí)r就下降，使晝夜平分點(diǎn)成為它們調(diào)節(jié)年鐘的最佳時(shí)期。

So ask a reindeer what time of year it is, and it may be able to give you the date. Just don't be offended if it won't give you the time of day.

所以，要問(wèn)馴鹿這是一年中的什么時(shí)段，它可能會(huì)給你個(gè)準(zhǔn)確的日期，可如果它答不上來(lái)現(xiàn)在幾點(diǎn)的話你就別生氣了。


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