Experts studied 230 pictures of major league baseball players printed in the 1952 Baseball Register.

　　专家们从1952年的一些主要的棒球联盟中研究了230名注册棒球队员的照片。

　　The researchers ranked each player according to whether they had no smile at all, a partial smile, where only the muscles around the mouth were involved, or a full-blown smile that featured a toothy grin, raised cheeks and creases around the eyes. The researchers then compared the photos with the life span of each player.

　　专家们按队员们的笑容进行等级分类，分别是“一点都不笑”，“笑了一点儿”，“微笑时嘴部肌肉有抽动”或是“笑的合不拢嘴”，以及“扬起脸，眼睛都笑出了皱纹”等这几个分类。然后他们把这些照片与队员们的寿命进行了比较。