Baby monkeys playing at Wuyishan (stump-tailed macaques)

For commentary on the unusual grooming behavior, here is an opinion by a primatologist. So for anyone curious about that, there's the answer: “Looks like the adults are just grooming that infant, not to stimulate urination but just as part of overall grooming. You can see that more than one female is doing mothering behavior, which is common. Usually the actual mom doesn't tolerate too much of that.“