"No one knows [how strong gorillas are], because you can't take a gorilla down to your local gym, obviously, and if you did it would be at your own peril and the other gym members' peril. We don't know, but scientists estimate it to be about 10 times stronger than a full-grown man. And certainly some of the things I've seen here at the zoo, 10 times stronger is probably fairly correct. For example, when I'm moving things around inside their enclosure, there might be very large logs which I'm literally unable to move, so I might call a couple of other keepers over, and between the three of us, we will slowly manhandle it, perhaps a few inches across the enclosure. Bobby then will come in and then just with one hand will be able to swipe that same log a good few feet without any effort."
—Daniel Simmonds, Gorilla Keeper, ZSL London Zoo