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Why did the orangutan cross the forest canopy¹? Presumably, to reach some tasty fruit. But the better question might be: how did the orangutan cross the forest canopy. And according to a study published in the Proceedings² of the National Academy of Sciences, the answer is something of a surprise.

Large apes that spend a lot of time in the treetops face a major challenge in getting to their food: how can they maneuver³ their bulk over those spindly little outermost⁴ branches, which hold all the best fruit? Scientists had predicted that the best way to navigate⁵ the canopy would be to swing underneath⁶ the branches, or to crawl over them carefully with knees and elbows flexed⁸.

But orangutans have a different approach. They like to mix it up. Sometimes they move upright, sometimes horizontally with their limbs fully⁷ extended. They avoid repetitive motions, which could make their perches⁹ sway even more precariously¹⁰. And they tend to grab on to more than one branch at a time—a third of the time they’ve got hold of more than four at once. Which is good because the apple might not fall far from the tree, but an orangutan doesn’t want to fall at all.