Eyebrows Could Have Been Our Main Competitive Advantage 眉毛或是人类重要竞争优势

施佳能

You probably already know the function of your eyebrows—they divert sweat and raindrops away from your eyes. However， they are also extremely expressive—we can guess pretty accurately what other people are feeling just by looking at their eyebrows. Now scientists from the University of York say that our eyebrows could have been a major benefit for survival.

Humans are the last surviving hominin1， Neanderthals2 are long gone. In fact， while they were slowly dying out， we were dominating the planet. And conditions were rough. So how did we manage to survive while other species came and went？ There is no simple explanation， but eyebrows might have been a key. You see， you can tell the emotion of the smiley face scribble3 on a piece of paper just by looking at his eyebrows—they are really that important. However， our ancestors did not have such expressive eyebrows. In fact， their eyebrows had little to no mobility and were characterized by a prominent bone ridge.

Scientists used 3D modelling techniques to create a digital model of the Kabwe 1 skull4. It does have a prominent eyebrow ridge， but scientists managed to shave it off5 to see what effect it would have on the mechanical performance of the bones. At it didnt have any—this ridge did not participate in distribution of biting forces. It might have been useful to protect the face （as a bumper）， but scientists argue that social functions were more important. But what kind of social functions could eyebrows have？

Now you know eyebrows are used subconsciously to express emotions. In fact， when youre pretending to be angry， you move your eyebrows down and closer together and when you are surprised， you raise them high. But eyebrows can communicate a huge variety of emotions and it was very important when humans started forming social groups. You cannot know every member of a large group， so how do you know what he is thinking and if you can trust him？ Unless you have mind reading powers， you will have to guess by facial expression.

And so mobile eyebrows could have helped humans to form social bonds which were crucial for our survival. Dr Penny Spikins， co-author of the paper， said： “While our sister species the Neanderthals were dying out， we were rapidly colonising6 the globe and surviving in extreme environments. This had a lot to do with our ability to create large social networks—we know， for example， that prehistoric modern humans7 avoided inbreeding8 and went to stay with friends in distant locations during hard times”.

It is also interesting that other studies showed that people who had botox9 injected into their foreheads and as result have less mobile eyebrows are less able to empathise and identify with10 the emotions of others. So it is better to let eyebrows be， because they might as well be our main evolutionary advantage.

你可能已经知道眉毛的功能——让汗珠和雨滴绕道，使其不流进眼睛。然而，眉毛也极具表现力——看看别人的眉毛，就能相当准确地猜出他们的感受。英国约克大学的多位科学家称，眉毛可能是我们生存的一大优势。

人类是仅存的人科成员，尼安德特人早已灭绝。事实上，在他们慢慢走向灭绝的同时，我们正在占领地球。当时的环境很恶劣。那么，其他物种出现又消失的同时，我们是怎么活下来的？说来话长，但眉毛可能是一个关键因素。要知道，纸上随手画的笑脸只要瞧一眼眉毛，就能看出表达的情绪——眉毛确实非常重要。但我们的祖先并没有这样富有表现力的眉毛。事实上，他们的眉毛几乎不能动，其特征是有根突出的骨脊。

科学家运用3D模型技术打造了一具名为“卡布韦1”的头骨的数字模型。该头骨上的确有突出的眉脊，但科学家削掉了眉脊以了解这会对头骨其他部分的力学性能产生什么影响：结果没有任何影响——咬合力与眉脊无关。或许眉脊有保护脸部的作用（相当于保险杠），但科学家认为，其社交功能更重要。那么，眉毛可能有什么社交功能呢？

要知道，人会下意识地用眉毛来表达情感。确切地说，假装生气时，人会向下皱眉;感到意外时，会扬眉。眉毛能传递许许多多的情感，在人类开始形成社会群体时起了非常重要的作用。在一个大群体中你不可能认识所有人，那么如何知道对方在想什么？如何知道能否信任他？除非你会读心术，否则只能靠面部表情来猜测。

因此，灵活的眉毛可能帮助人类形成对生存至关重要的社交联系。相关论文的合著者彭妮·斯皮金斯博士说：“我们的同类物种尼安德特人逐渐消失的同时，人类在地球上迅速聚居，在极端恶劣的环境下继续存活。这与我们建立大型社交网络的能力有很大关系——比如，我们知道，史前的现代智人避免同系交配，在艰难时期，会和远方的朋友待在一起。”

同样有趣的是，另有研究表明，因前额注射肉毒杆菌导致眉毛不灵活的一些人，他们与别人产生情感共鸣的能力较弱。因此，最好讓眉毛保持原样，因为它们也许是我们重要的进化优势。

（译者为“《英语世界》杯”翻译大赛获奖者）