How long do apes nurse their young

One of the orangutans was shot when it was nearly nine years old, and still had barium in the outer layers of its teeth. Not only does it mean that orangutans nurse longer than any known primate, but it could reveal important information about how breastfeeding evolved in humans. The team hypothesizes that during food shortages, orangutans breastfed their older kids instead. In turn, that could help other researchers figure out times of environmental variation for early humans or even when they started living longer and needing less breast milk.

Barium has already revealed clues about prehistoric humans: In , researchers found that one Neanderthal breastfed continuously for about seven months and stopped intermittent feeding by 1. Perhaps information about how orangutans breastfeed—and how that milk benefits their young—could one day influence how long their human cousins nurse their babies. Erin Blakemore is a Boulder, Colorado-based journalist.

Learn more at erinblakemore. Orangutans may not wean for years, a new study shows. Post a Comment. 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. For the new research, Tanya Smith and colleagues developed a creative method for tracking how long orangutans nurse: Analyzing the levels of barium, a trace element, in young orangutans' teeth. Because barium absorbs into young orangutans' skeletons from their mother's milk, it can reveal how long an orangutan had been nursing. Two species of orangutan—whose name comes from the Malay word for "person of the forest"—swing from the trees in Sumatra and Borneo: The Sumatran orangutan, Pongo abelii, and the Bornean orangutan, Pongo pygmaeus.

Also see " Pictures: Saving Sumatra's Orangutans. Smith, a biological anthropologist at Griffith University, and team studied the teeth of four immature orangutans, two from Borneo and two from Sumatra. The animals had been shot during collecting expeditions many years ago, their bones then housed in museums. By studying growth patterns and barium levels in the specimens' molars, the team determined the animals' barium levels decreased after one year of age, but that the element was still there nearly a decade later, according to the study, published this week in Science Advances.

For instance, one Bornean orangutan weaned at 8. Orangutans have their first offspring around 15 years of age and are believed to live up to 50 years in the wild. See " 10 of Our Favorite Orangutan Pictures. The teeth also showed cyclical periods of high and low barium concentrations that corresponded with fruit abundance: When fruit was plentiful, barium levels were lower.

That suggests that in times of scarcity, young orangutans may "fall back" on mom's milk to get them through, says Smith. Read more about Knott's work on orangutans in her own words. The unpredictable environment is also likely why orangutans mature more slowly—there's rarely a surplus of food that could fuel rapid growth.

Indeed, if the fruit supply were more reliable, it's likely orangutans would not nurse so long, she says. Captive primates tend to mature more quickly than their wild counterparts, for instance, presumably because they eat consistently and nutritiously, Smith notes. Since they reproduce so slowly, orangutans are particularly vulnerable; deforestation for palm oil plantations has dwindled their numbers, and they are now critically endangered.

The island of Borneo map has lost more than 50 percent of their orangutan population in the past 60 years, and in the past 20 years the species' habitat has decreased by at least 55 percent.

On Sumatra map , just under 15, remain, according to WWF. That's a drop from possibly , of the primates a century ago. Smith and colleagues' study suggests there need to be more research into orangutan moms and babies, Knott adds.

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