眉毛是干什么用的？

Eyebrows have become an obsession of late, tattooed or microbladed, shaped and drawn in bold dark lines, making a statement far beyond braiding or waxing.

近来，人们似乎痴迷于眉毛，纹眉或剃眉，修眉，然后画上显眼的深色线条，这样做所表达的意思远远超过编辫子或脱毛。

Lifting one and not the other often signals disbelief, amusement, curiosity. Raising both can suggest surprise or dismay. But it wasn’t always that way.

只扬起一条眉毛，往往表示怀疑、逗趣或好奇。扬起两条眉毛则表示惊讶或沮丧。但也不一定都是这样。

Early humans had thick, bony brow ridges that were far less nimble than ours, incapable of expressing much of anything beyond, “Don’t mess with me, Thag.”

早期的人类有着厚厚的、骨感的眉脊，远不如我们的灵活，无法表达很多意思，除了“你这鸟人，别惹我。”

Scientists have long thought those brows served some structural purpose, like support for chewing prehistoric food. That they could also be used to signal aggression or intimidate competitors was largely dismissed as an evolutionary perk, as were the more flamboyant brows of modern humans.

长期以来，科学家们一直认为，从身体结构的角度讲，眉毛有一定的作用，比如有助于咀嚼史前的食物。它们也可能被用来表达敌对情绪或恐吓竞争对手——这些也基本上被认为是进化上的好处，就像现代人更艳丽的眉毛。

But when Ricardo Miguel Godinho, an evolutionary anthropologist at the University of York, made digital recreations of a skull believed to be 300,000 to 125,000 years old, he found no evidence that its brow ridges provided any of the practical benefits suggested by earlier studies. “He tested out the different possible explanations, and, effectively, there’s no reason for it,” said Penny Spikins, an anthropologist who conducted the study with Dr. Godinho.

但是，约克大学(University of York)的进化人类学家里卡多·米格尔·戈迪尼奥(Ricardo Miguel Godinho)对一个被认为是30万至12.5万年前的头骨进行数字重建时，并没有发现任何证据表明，眉脊提供了之前研究中提到的任何实际益处。“他测试了各种可能的解释，但实际上，找不到任何根据，”与戈迪尼奥博士一起进行这项研究的人类学家彭妮·斯皮金斯(Penny Spikins)说。

The findings, published April 9 in Nature Ecology & Evolution, suggest that the human brow has always been a primarily social tool, and that the smoother foreheads and expressive brows of modern humans may have evolved to accommodate our increasingly complex relationships.

4月9日发表在《自然生态与演化》(Nature Ecology & Evolution)杂志上的研究结果表明，人类的眉毛一直主要是一种社交工具，现代人类的前额更平滑，眉毛更具有表现力，也许是为了适应我们日益复杂的人际关系。

“With a flatter, more vertical forehead, that whole area above the eyes becomes much more mobile, and the muscles can make some really subtle communicative gestures,” Dr. Spikins said. And those gestures, like lifting your eyebrows to show you recognize someone, she said, “tend to be more about expressing friendliness than intimidation.”

“有了更平坦、更竖直的前额，眼睛上方的整个区域就变得灵活了很多，肌肉也能做出一些非常微妙的交流示意，”斯皮金斯说。她表示，那些示意，比如扬起眉毛表示你认出了某人，“更多的是表示友好，而非恐吓”。

Though such a hypothesis is difficult to test without a time machine, Dr. Spikins said it emerged from the real-life observations of Paul O’Higgins, a co-author of the study. “Paul was frustrated that his daughters spent so much time in the bathroom mirror perfecting their eyebrows, and was saying, ‘What are eyebrows for?’” she recalled. “That’s when we thought maybe this is actually quite important.”

虽然这样的假设在没有时光机器的情况下很难验证，但斯皮金斯表示，它源于这项研究的联合作者保罗·奥伊金斯(Paul O’higgins)对真实生活的观察。“保罗为女儿们花很长时间对着浴室的镜子修眉毛感到沮丧，他说，‘眉毛是干什么用的呢?’”她回忆道，“所以，我们当时想到，这也许是个很重要的问题。”