科學界最令人困惑問題之一 我們爲什麼會打哈欠3

Perhaps the best evidence comes from twotroubled women who approached Gallup soon after he first published his were looking for relief from pathological yawning attacks, sometimeslasting an hour at a time. “It was extremely debilitating and interferes withany basic activity,” says Gallup. “They’d have to walk away and go to a secludedarea – it affected their personal and professional lives.” Intriguingly, one ofthe women found the only way to stop the yawning attack was to throw herself intocold water. Inspired, Gallup asked them to place a thermometer in their mouthsbefore and after the attacks. Sure enough, he saw a slight rise in temperaturejust before the yawning bouts, which continued until it dropped back to 37C.

可能最好的證據來自於兩位受哈欠困擾的女士，她們在蓋勒普第一次發佈了他的研究成果後便找到了他。這兩位女士都患有疾病性的哈欠症狀，有時候哈欠會一次持續一個小時之久，她們一直都在尋找治療方法。“當某項日常活動出現了問題，日常生活就會遇到極大的困擾與麻煩，令人身心俱疲，”蓋勒普說。“他們就不得不遠離他人，走到一個隱蔽的區域——從而影響到他們的私人以及職業生活。”有趣的是，其中的一位女士發現唯一能讓自己停止打哈欠的辦法就是把她整個人浸入冷水當中。受到這一方法的啓發，蓋勒普讓她們在打哈欠之前及之後都要將一個溫度計放入各自的嘴裏。果然，蓋勒普觀察到了溫度在哈欠剛發作之前有所輕微上升，持續一段時間後溫度再度回落到37℃。

Importantly, this brain chill mightunderlie the many, seemingly contradictory, events that lead to yawning. Ourbody temperature naturally rises before and after sleep, for instance. Coolingthe brain slightly might also make us more alert – waking us up when we arebored and distracted. And by spreading from person to person, contagious yawnscould therefore help a whole group to focus.

重要的是，這一冷卻大腦的作用可能能夠解釋衆多看似矛盾的會導致打哈欠的各類原因。比如我們的體溫在睡覺之前、之後會自然地上升。對大腦進行稍稍的冷卻也可以讓我們變得更加警覺，當我們無聊、走神的時候可以重振我們的精神。通過人與人之間的互相感染，打哈欠能夠幫助一個團隊的人集中起注意力。

Gallup’s unified theory has been somewhatcontentious among yawning researchers. “Gallup’s group has failed to presentany convincing experimental evidence to support his theory,” says Hess. Inparticular, his critics point out he hasn’t made direct measurements oftemperature changes in the human brain, though Gallup says he has found theexpected fluctuations in yawning rats. Provine is more positive, however –believingthat it could be one way in which yawning helps the brain change state, andfocus.

蓋勒普這一統一的理論在哈欠研究者之間引起了爭論。“蓋勒普的團隊沒有拿出任何有說服力的實驗證據來支持他的理論，”赫斯這樣評價。他的批評者尤其指出了他並沒有對人腦的溫度變化進行直接的測量，儘管蓋勒普本人說他自己在打哈欠的老鼠身上已經發現了預想當中的溫度波動。普羅文對此則持更爲積極的態度，他相信這可能是打哈欠幫助大腦改變狀態以及集中注意力的一種途徑。

Even if Gallup has managed to find thatunified theory, many mysteries remain. Why do foetuses yawn in the womb, forinstance?

即使蓋勒普成功找到了這樣一個統一化的理論，仍有很多的謎題有待解開。比如爲什麼胎兒會在子宮裏打哈欠？

It could just be that they are practicingfor life outside, or perhaps the yawn plays a more active role in guiding thebody’s growth – by helping to develop articulation in the jaws joints, forinstance, or by encouraging the growth of the lungs, says Provine. If so,Provine suggests that yawning’s functions in the womb may be more important than our attacks asadults.

普羅文說胎兒可能是在爲外面的生活做演練，或者也有可能是打哈欠能夠促進身體的生長——比如促進頜關節或是肺器官的發育。如果是這樣的話，普羅文就認爲子宮內哈欠的作用可能比我們成人在外界打的哈欠來得更爲重要。

Provine also points out that yawning – andperhaps other bodily functions, like sneezing – shares some strange parallelswith sex. The facial expressions involved are surprisingly similar, he says –just take a look at this picture and you can see where he’s comingfrom.

普羅文還指出打哈欠——可能還有其他身體機能比如打噴嚏——同性行爲有着神奇的聯繫。兩者的面部表情驚人得相似，普羅文說——看一看這張圖片你就能看出他剛經歷了什麼。

Like sex, yawns and sneezes involve abuild-up that ends in a pleasant climax. “Once initiated, they go to completion– you don’t want a yawnus interruptus,” is how Provine puts it. For thesereasons, he wonders if a shared neural machinery underlying these differentfeelings. “Mother Nature does not reinvent the wheel,”he says. Asevidence, he points to the fact that certain anti-depressants can lead somepatients to orgasm during a yawn –a rare side effect that could quickly lose its appeal.

同性行爲類似，打哈欠與打噴嚏涉都有一個快感積累，並以高潮結束的過程。“這種行爲一旦啓動，就必須進行完整——你可不會希望有人在你打哈欠的時候打擾你，”普羅文如此解釋。基於這些原因，他想知道的是在這些不同的感覺背後是否有一種共享的神經機制。“大自然母親不可能把輪子發明兩次，”普羅文說。作爲證據，他指出這樣一個事實，那就是某一種特定的抗抑鬱藥能夠導致某些病人在打哈欠過程中體會到性高潮——這是一個很快就會失去其吸引力的罕見的副作用。

Eventually, the temptation to yawn justproved too irresistible during my conversation with Provine. It was a warmsummer day, so perhaps my yawns were stopping my brain from over-heating duringour stimulating conversation. Whatever function it was serving, the relief wasalmost worth the agonising wait.

最後，在同普羅文交談的過程中，打哈欠的誘惑是如此得無法抵抗。那是一個溫和的夏日，所以我的哈欠可能是在防止我的大腦在我們的談話中升溫過度。不論它發揮着什麼作用，最終的釋放值得此前煎熬的等待。

I’m willing to bet you’ve been stifling afew yawns yourself by this point – as Provine points out, reading or eventhinking about yawning can be enough to set us off. So go ahead, let it out –and do so in the knowledge that you are enjoying one of life’s most enduringmysteries.

我敢打賭現在的你看到這裏肯定已經打了好幾次的哈欠——就像普羅文指出的那樣，閱讀或甚至是想到打哈欠這件事都會足夠引起哈欠。所以別憋着了，盡情地張開嘴吧——要知道你可是在享受一個生命最持久的祕密。