The temple and chin patches are most prominent and common, though I have seen one person with only the jaw-angle white patch. No matter what the pattern, these patches continue to expand until the entire beard is white, and eventually the moustache. Finally, the eyebrows whiten, almost always last. Once the facial hair is far along in graying, the back, shoulder, and chest hair begins to gray. Leg and arm hair, as in the gorilla, usually remains colored, but often there is a tendency to fleck gray.
Gibbons are the best example of the latter.
The entire face is white-rimmed. I believe that if contrast is selected for there is a tendency to stripe one line upon another as in the striped tail of the ring-tailed lemur. Once a dark line is contrasted against light, it is easy to make the light color look even sharper by adding another dark line on its other side and so on. That jaw angle spot added to the temple and chin spots by giving contrast to the color in between, and at the same time artificially extended the moustache line across the cheek. This latter phenomenon can be seen in the horn contours of some antelope, being broadcast down upon the face by a black line passing through the eye, for example, in the oryx antelope and roan antelope.