Five methods of food cleaning used by Western lowland gorillas in this study: A) Finger B) Palm C) Back of Hand D) Forearm E) Substrate; see S1 File for video recordings.

<p>Five methods of food cleaning used by Western lowland gorillas in this study: A) Finger B) Palm C) Back of Hand D) Forearm E) Substrate; see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0188866#pone.0188866.s001" target="_blank">S1 File</a> for video recordings.