Chimpanzees are considered quadrupedal (walking on four limbs), but they don’t have four legs like many other mammal species. Like humans, they have two legs and two arms. They not only share our handy (pun intended) opposable thumbs, but they have “thumbs” (technically referred to opposable toes) on their feet too.
Animals with four legs generally have limbs that are pretty much equal in length and they walk on the same part of each of their feet. Chimpanzees have long arms with long-fingered hands and they bend their fingers underneath, walking on the knuckles of their hands and the flat part of their feet.
One cool thing about knuckle-walking is that it leaves your hands free to carry your dolls:
While chimpanzees are mainly quadrupedal when walking and standing (of course they can also swing through the trees), there are times when they stand up on their feet and sometimes walk bipedally like us humans.
At the sanctuary, a frequent reason to stand up is to spy on the neighbors or spot something at a distance:
Another pretty practical reason to walk bipedally is when your hands or arms are really full:
Being short myself, maybe I’m projecting this on to Missy, but I think I stand up straighter and raise up on my tip toes a lot more than less vertically-challenged people, so I equate this to Missy standing up just to be taller once in a while:
Annie, however, is somewhat of an exception. We don’t really know why, but she tends to stand and walk bipedally more often than not when she’s in the grass on Young’s Hill, even when her hands aren’t full and she’s not trying to spy on something at a distance.