Chimpanzee communities in the Mahale Mountains NP may spend up to 23% (!) of their daytime hours grooming. The purpose of all this grooming is to remove parasites such as lice and ticks, as well as to strengthen social relationships between individuals. Not a unique position to Mahale Mountains NP but certainly not practiced in all other chimpanzee communities either, is the grooming hand clasp.
An interesting position in which two chimpanzees groom each other simultaneously -- both arms upheld in the air -- clasping their hands together while they groom armpits or underarm parts.
As we observed these two chimpanzees taking all the time in the world to meticulously groom each other, they moved from a variety of grooming positions to the hand clasp and back. You can really see why it's comfortable to groom and to be groomed.
There is some sort of peacefulness that falls upon you while seeing these apes do this.
For more wonderful blogs by Bas and Suzanne at Greystoke Mahale please go to http://www.nomad-tanzania.com/blogs/greystoke-mahale/