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Orangutans have staggeringly low rates of infant mortality. They are better at keeping their offspring alive than people in most human societies throughout history.

“We see this incredibly high survival that’s higher than any [non-human] mammal that we know of so far,” says Maria van Noordwijk at the University of Zürich in Switzerland.

The high survival rate is linked to orangutans’ lifestyle, which is more solitary than other apes. But it also puts them at risk, because it is tied to their low birth rate – meaning they would struggle to recover…