Tag Archive: fruit

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Endangered orangutans offer a new evolutionary model for early humans

December 15th, 2011 / tags:, , , , , , / categories: Uncategorized /

ScienceDaily (Dec. 13, 2011) — Starving orangutans in Borneo may be teaching us new lessons about human evolution.

Nathaniel Dominy, associate professor of anthropology, has been studying the dietary habits of these apes: what food they eat and how they digest it. “We are interested in how orangutans cope with food-limited environments because it may give us a glimpse into what early human ancestors were facing,” Dominy explains. He and his colleagues report on a study of orangutans under dietary stress in Borneo in the December 14 online issue of Biology Letters, a journal of The Royal Society.

The apes that gave rise to the earliest human ancestors had teeth that are much like orangutan teeth. The resemblances are particularly strong between the teeth of the pre-human apes and those of the stressed animals living on Borneo. Dominy suggests that the orangutans’ diet may have exerted a selective pressure on their molar teeth. If we understand the physical properties of their food, then we may have some idea of why humans evolved the teeth that we have.

The Borneo environment is stressful. The soil is not very fertile and plants crop unpredictably, only producing quantities of fruit every four or five years. When they do bear fruit, the whole forest produces at once. The animals gorge themselves, put on fat, and then live off these reserves for the next three to four years. Unchecked logging that is reducing orangutan habitat worsens this already inhospitable situation.

Orangutans prefer ripe, soft, juicy fruits but during the “off-years” on Borneo when nothing else is available, the orangs resort to eating very hard and tough foods. Dominy describes how they rip bark off trees and eat the starchy tissues behind the bark. They will also eat very hard seeds. This far less nutritious diet seems to supply just enough protein to survive.

The five-year study described in the Biology Letters paper documents the adaptive metabolism of these apes in these protein-deficient hard times. Orangutan urine was collected on Borneo and analyzed for dietary markers, such as ketones, which increase when the body breaks down fat for energy. When fruit abundance was lowest, the ketones surged, demonstrating that the animals were burning their fat reserves — using more energy than they were taking in. As long as the fat holds out, the situation is tolerable.

When body fat is depleted, the next stage is cannibalizing muscle tissue. Elevated nitrogen isotopes in the urine of some individuals indicate that muscle wasting was indeed a source of the protein that kept the animals alive.

Professor Dominy considers the lean years for orangutans on Borneo to be a selective pressure that led to evolutionary adaptations since the population became isolated 400,000 years ago. He argues that the larger molars and more robust jaws among the Borneo orangutans developed in response to the hard, tough foods they consumed during the periods between fruit availability — an enduring adaptation to an occasional situation.

Recent studies of wear patterns on the huge molars of early hominids suggest that they only ate a more physically challenging diet some of the time. These hominids may be displaying an adaptation that helped them to get through evolutionary pinch points, similar to what the orangs encounter.

Our ancestors experienced selective pressure favoring adaptations to hard objects, but it’s possible that they didn’t eat hard objects consistently.

“Perhaps the hard objects were things they ate only very occasionally under ecological duress,” Dominy muses. “It is not what they ate regularly that matters. It is what they were eating during crunch times. Because they routinely go through these dire times, orangutans may be a good model for what happened to human ancestors in deep time.”

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The above story is reprinted from materials provided by Dartmouth College. The original article was written by Joseph Blumberg.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

  1. E. R. Vogel, C. D. Knott, B. E. Crowley, M. D. Blakely, M. D. Larsen, N. J. Dominy. Bornean orangutans on the brink of protein bankruptcy. Biology Letters, 2011; DOI: 10.1098/rsbl.2011.1040

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

Article source: http://www.sciencedaily.com/releases/2011/12/111213203319.htm

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Starving orangutans might help to better understand obesity and eating disorders in humans

December 14th, 2011 / tags:, , , , , , , , , / categories: Uncategorized /

ScienceDaily (Dec. 13, 2011) — Rutgers evolutionary anthropologist Erin Vogel thinks new research published December 13 in Biology Letters, a Journal of the Royal Society, examining how endangered Indonesian orangutans — considered a close relative to humans — survive during times of extreme food scarcity might help scientists better understand eating disorders and obesity in humans.

“There is such a large obesity epidemic today and yet we don’t really understand the basis of the obesity condition or how these high-protein or low-protein diets work,” said Vogel, whose research, Bornean orangutans on the brink of protein bankruptcy, represents the first time scientists have looked at how these long-haired, orange-colored apes — that depend on low-protein fruit to survive — endure protein cycling, or period bouts of protein deprivation. “I think studying the diets of some of our closest living relatives, the great apes; may help us understand issues with our own modern day diets,” she said.

According to Vogel, an assistant professor of anthropology in Department of Anthropology and Center for Human Evolutionary Studies, in the School of Arts and Sciences, the research shows that it is only during periods of high caloric and protein intake that orangutans put on fat, a scientific fact that is sometimes ignored by those who believe that high protein, low carbohydrate diets are the best way to lose weight. She said it is only when caloric intake is restricted that orangutans use these fat reserves for energy and eventually dip into their protein (muscle) reserves — a condition that is seen with eating disorders like anorexia.

Orangutans in particular are interesting to study, Vogel said, because they are the only documented species of non-human ape to store fat when food is abundant in the wild and use these fat reserves when preferred fruits become scarce, presumably something done by our early hominin ancestors.

Vogel and her research team, analyzed samples collected over a five-year period to study the effects of protein recycling, which included examining urinary metabolites and nitrogen stable isotopes — compounds and byproducts in Orangutan urine. What they determined is that these primates are able to endure prolonged protein deficits without starving to death by consuming higher protein leaves and inner bark and obtaining energy from their stored body fat and even muscles for an extended period of time when low-protein fruit is unavailable.

“We discovered through this research that the daily amount of protein the orangutans take in when fruit is not available is inadequate for humans and one-tenth of the intake of mountain gorillas. But it is sufficient to avert a severe protein deficit,” said Vogel.

The Bornean orangutan population has fallen drastically in the last 50 years in Indonesia to less than 55,000 and on the island of Sumatra to less than 5,000 due to a massive amount of illegal logging and further clearing of the land to develop palm oil plantations in their now impoverished rainforest habitat. Vogel says that although some palm oil companies argue that clearing partially logged areas of the rainforest for palm oil plantations is not detrimental to the existence of the orangutan because their natural habitat has already been taken away, this research on protein cycling indicates that even areas that have been partially stripped of trees are better for orangutan survival than no forest area at all.

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Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

Article source: http://www.sciencedaily.com/releases/2011/12/111213203317.htm

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Orangutans shed light on obesity in people

December 14th, 2011 / tags:, , , , / categories: Uncategorized /

CHICAGO (Reuters) – In lush times, orangutans on the island of Borneo gorge themselves on forest fruits, packing on extra pounds in preparation for leaner years, when they live off leaves and bark and their own stored fat.

This behavior of overeating is all too common in humans, but rarely seen in nonhuman primates, and studying it may offer some clues about obesity and eating disorders in people, U.S. researchers said on Tuesday.

“Orangutans make very interesting models for studying human obesity because they are really the only apes and potentially the only nonhuman primates in the wild that actually store fat deposits,” said Erin Vogel, an evolutionary anthropologist from Rutgers University in New Jersey, whose study appears in the journal Biology Letters.

“It’s never been documented in any other species,” Vogel said in a telephone interview.

Vogel and colleagues studied urine samples from Bornean orangutans laboriously collected over a period of five years by a team led Dr. Cheryl Knott, a biological anthropologist at Boston University.

“Orangutans living in this really challenging habitat are able to take advantage of these periods of incredible fruit abundance — these masting periods, where 80 percent of the fruit on the trees are fruiting,” Vogel said.

“They eat and eat and eat and they get fat,” she said.

Then they go through periods of very low fruit production that can last up to eight years.

In the study, as food stores became more and more scarce, the orangutans shifted to bark and tough leaves to survive. And the team noticed changes in the apes’ urine.

First, they saw ketones, a sign that the body was metabolizing fat. “It indicates they are burning this fat for energy,” Vogel said.

And then they saw elevated nitrogen isotopes. These indicated that muscle cells were being broken down to obtain protein and energy.

“They have to get energy from somewhere, so they start to digest their body tissue, just like you would find in situations were humans are very impoverished, and in anorexia, where we would potentially see conditions where humans would digest their own muscles,” Vogel said.

Vogel credits Knott’s team for collecting the urine samples, which was no mean feat.

The team followed the orangutans from the time they woke up in their nest until the time they went to sleep.

“As soon as they wake up, they typically void — they urinate,” Vogel said.

Knott’s team would be waiting underneath the tree canopy to collect these samples, either with plastic sheeting or an inverted umbrella held over their heads, which worked as both a collection device and some protection from the shower of urine.

Vogel said the study shows how orangutans have taken advantage of their ability to store fat to increase their chances of survival, but this same ability is a deficit for most humans who do not need to forage for food.

“We have this wonderful ability to store fat, and now most of us wish we didn’t have it,” she said.

In future studies, Vogel said she plans to look for fluctuations in the hunger-related hormones ghrelin and leptin during periods of food scarcity and abundance, as well as changes in inflammatory cell signaling chemicals known as cytokines, which are thought to play a role in obesity.

Orangutans are endangered. There are only 50,000 individuals remaining in Borneo and 7,300 in Sumatra — the two places in the world where they can still be found in the wild.

(Editing by Vicki Allen)

Article source: http://news.yahoo.com/orangutans-shed-light-obesity-people-005451686.html

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