Thursday, December 15, 2011

How Borneo orangutans avoid starvation in lean times

They use body fat and muscles as energy until bounty of food is available, study shows

Orangutans in Borneo can survive potential starvation by using their body fat and muscles as energy until a bounty of food is available, researchers find, adding that the results may someday shed light on the eating habits of our earliest ancestors.

The findings may also speak to various low-carb, high-protein diets, because essentially weight comes down to caloric intake for these orangutans as it does us, the researchers say.

In Borneo, an island in Southeast Asia, forests go through periods of high fruit yield, where around 80 percent or more of the plants will produce fruit all at once. Following these "masting" periods, the forests endure stretches of sparse fruit availability that can last anywhere from two to eight years. To survive in this unpredictable environment, orangutans put on fat by gorging on fruits when they're available, and then live off of these reserves until the next masting year.

Researchers have now learned that the orangutans start to metabolize their own muscles for protein after these fat reserves are gone.

"In this stage there is evidence of tissue wasting, the same kind that you would observe in anorexic patients," said Erin Vogel, an evolutionary anthropologist at Rutgers University and lead author of the new study.

Vogel and her colleagues also learned that the primates avoid extreme protein deficiency by eating tough foods, such as leaves and bark, using highly adapted molars, not unlike those found in modern humans and our hominin ancestors. By comparing the physical properties of orangutans' teeth and food with those of other primates, scientists may someday be able to tease out the diets of our ancestors, Vogel said.

The importance of protein

Protein is important for the growth and reproduction of all animals, but few studies have investigated how wild animals maintain protein balance, the researchers said. This question is especially interesting for species in Borneo because of the island's seemingly inhospitable fruit-crop cycles.

Continue reading (Incl. Pic) at: How Borneo orangutans avoid starvation in lean times

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