At age 44, Xie Qiuping cut her hair for the first time in over three decades. Her impressive locks extended over 5 meters — earning the Guinness World Record for the world’s longest hair. But even with this record-setting feat, her hair might not have reached its maximum possible length. So, just how long can human hair actually grow? Maksim Plikus digs into what factors influence hair growth. Lesson by Maksim Plikus, directed by Matt Partridge.