I hung some gymnastic rings over a rafter in my garage. I wish they were in the living room because I really like them. Whenever I walk by I like to swing a little back and forth, left and right, in circles, with one or two arms. I think part of the reason I like swinging on the rings so much is that my ancestors probably engaged in lots of similar activity when they lived in trees. Brachiation is a very interesting form of locomotion that is used by primates to swing from one tree branch to the next. This may seem like an awkward way to get around, but it can be incredibly efficient and powerful. Gibbons are the master brachiators, and can reach speeds up to 35 miles per hour. That’s faster than Usain Bolt can run.
Humans have many characteristics which suggest a brachiator ancestor, including flexible shoulders, long arms, rotating wrists, and clasping hands. But they are nothing compared to the gibbons. Here’s a video of a gibbon showing some humans what they missed out on by leaving the trees for the savannah:
Wow, look at that power. Gibbons are bad asses. These guys have some incredible agility as well. Here’s a video of a gibbon taunting some tiger cubs. What could be cuter!
Aww, it’s like a real life Walt Disney video, complete with sound effects! The only thing missing is a song from the Jungle Book.
In all seriousness, I was amazed by this gibbon’s skills. He outmaneuvered the tigers like ten times in two minutes, in each instance putting his life on the line. If he had grabbed for a branch and missed, he would have been lunch. Fortunately for him, evolution in the trees has given him a mind with awesome visual processing and hand eye coordination. These talents are very expensive in terms of brain tissue, and Steven Pinker has speculated that the mental demands of arboreal life and locomotion were a key factor in how humans grew such big brains.
So what does brachiation look like in humans after a few million years of neglect? A little rusty, but not too bad actually. Here's a video of what your average healthy six year old girl can do:
Look at that. Easy peasy lemon squeezey. Most girls seem capable of mastering the monkey bars in a short amount of time with no instruction at all, just by playing around. But why don’t boys like the monkey bars? A question for another day.