Behavior toward humans has baffled and intrigued scientists. There is little to no aggression, yet no fear, either. "Gorilla males will always charge when they encounter a hunter, but there were no stories like that" about the Bili apes, according to Ammann. Instead, they would come face-to-face with their human cousins, stare intently in half-recognition, then slide away quietly. Hicks's group later confirmed and somewhat expanded those observations, saying that when they encountered a large group of Bili apes in the deep forests (far from the roads and villages), they not only approached the humans, but also would actually surround them with intent curiosity. Hicks clarifies the issue as follows: the apes within 20 km or so of the roads flee humans almost without exception. The adult males show the greatest fear. Further from the roads, however, the chimpanzees become progressively "naive".