一张图看你看遍：百年人类笑容进化史

There's a reason why people 100 years ago looked miserable. A new study has revealed how our smiles have evolved in photographs as a direct result of improving technology.The research was done using a new data-mining tool, which can reveal patterns in anything from phone conversations to behaviour on social media.

100年前的人看着那么悲催是有原因的。随着技术的不断改进，一项新研究向人们揭示了照片中的"笑容进化史"。通过应用新的数据处理工具，这项研究得以揭示从电话谈话到社交媒体中的一切规律。

Ginosar looked at 150,000 yearbook photos as part of the study.After deleting photos that weren't face-on, she was left with around 37,000 images from 800 yearbooks in 26 states.

吉诺萨研究了15万张年鉴里的照片。去掉非正脸照片后，她留下了从26个州800本年鉴中找到的3万7千多张照片。

She then put the photographs together based on gender, and then decade, before they were blended into on another to create an 'average' face from each period.After analysing the images using her data mining tool, she found the most obvious difference between was the evolution of the smile, which gets broader as the years go on.

她先把照片根据性别和年份拼在一起，然后将这些照片重新排列，并从每个时期找出一张"大众"脸。通过运用数据处理工具解析图片，她发现其中最明显的区别莫过于微笑的演变，随着年代不断靠近，人们的微笑也越来越开怀。

Ginosar says this is because of changing technologies.'These days we take for granted that we should smile when our picture is being taken,' she writes in her report.'However, smiling at the camera was not always the norm.

吉诺萨称这是由于科技的进步。"如今我们理所当然地认为拍照时就该笑，"吉诺萨在其报告中写到。"然而并不是每个时代的人都会在拍照时微笑。"

'In the late 19th century people posing for photographs still followed the habits of painted portraiture subjects.

19世纪晚期，人们拍照摆的姿势依然模仿图画里的惯用动作。

'These included keeping a serious expression since a smile was hard to maintain for as long as it took to paint a portrait.

其中就包括一脸严肃的表情，因为要在画肖像的时候一直保持着微笑太难了。

'Also, etiquette and beauty standards dictated that the mouth be kept small - resulting in an instruction to 'say prunes', rather than cheese.

还有，当时礼数和美的标准都要求笑不露齿－所以人们拍照时摄影师会让人说"prunes"（开口度小），而不是"cheese"（开口度大）。

'All of this changed during the 20th century when amateurs photography became widespread.

这些现象在20世纪时才得以改变，因为当时业余摄影开始普及。