Lion-tailed macaques live in closely-knit troops of about 20, led by a single powerful male. Grooming is an important activity that keeps them together. It serves two functions: it helps them stay clean, and forms healthy bonds. Often, the lower-rank females groom the senior, dominant females to appease them. In return, they get food, protection or just tolerance. Sometimes the barter is simply for pleasure.

See a photo essay on the lion-tailed macaques here. And read a story on what it is like to spot them in the wild here.