Most jumping animals - such as frogs and grasshoppers - have some powerful adaptations that basically make their legs into giant springs. But our ape cousins manage to leap insane distances through sheer force of will, without any helpful adaptations.
Gibbons generally live high up in the rainforest canopy, which means they have to find ways to move between relatively distant trees. Since they're too heavy to swing directly, they sometimes have to leap. And make no mistake, they are prodigious leapers, covering as much as ten meters from a standing start.
Of course, such jumps are not without their dangers. Gibbons fall all the time, and any broken bones they sustain are just as likely to be fatal as anything else. But overall, the advantages of leaping in the canopy are too much to ignore. By staying high above the ground, the gibbons avoid running into dangerous predators like leopards and pythons, and the apes need to keep moving if they want to find the constant supply of high quality food that sustains their diet.
So, without any specific mechanical adaptation, how do the gibbons do this? Liverpool University researchers have been able to capture high definition video of a pair of gibbons jumping, and from that they were able to determine how the gibbons' centers of mass moved. The results were astounding - gibbons put more energy into their jumps than any other known animal, and five times as much as humans. In a standing vertical jump, a gibbon's center of mass would clear 3.5 meters compared to just .6 for a human.
The gibbons do this by using a crouch-and-lunge technique. They use their long arms, which are adapted for hanging from branches for extended periods, like long pendulums to propel themselves forward as they leap out of the crouch. This technique allows them to be fully stretched out before they even take off, which gives them an additional advantage over other primates in terms of "push-off distance." This technique is also useful in that it minimizes the downward force - a very good thing when you're jumping off of a fragile branch a hundred feet in the air.
Co-author Dr. James Usherwood explains just how special the gibbon leaping technique really is:
"By pushing against the branch for longer, large works can be performed accelerating the body without requiring large powers. Gibbons appear to hit a size 'sweet-spot', where they are big enough (helped by long arms and legs) to power jumps directly with muscle, but small enough to survive crashing about through trees. Much smaller, and they need to store energy in tendons like the smaller primates such as bush babies. Much bigger and the risk of injury becomes prohibitive - orangutans are exceedingly slow and safe."