The world's largest tree climbers, orangutans now have another superlative to their name: They nurse their young longer than any other primate, a new study says.

Surprising new research has revealed that the colorful great apes suckle for up to eight years, and in some cases longer.

Little is known about when the shaggy great apes wean in the wild, in part because they're so challenging to study—they spend most of their time aloft and out of sight. But knowing when juveniles strike out on their own is important for conservationists working to save them. (See "Orangutans Are More Like Us Than You Think.")

For the new research, Tanya Smith and colleagues developed a creative method for tracking how