Featured Research

from universities, journals, and other organizations

Endangered orangutans offer a new evolutionary model for early humans

Date:
December 13, 2011
Source:
Dartmouth College
Summary:
Studying how the orangutans cope with a harsh environment may offer a glimpse into what early human ancestors faced, new research suggests.

Starving orangutans in Borneo may be teaching us new lessons about human evolution.

Related Articles


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."


Story Source:

The above story is based on materials provided by Dartmouth College. The original article was written by Joseph Blumberg. Note: Materials may be edited for content and length.


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

Cite This Page:

Dartmouth College. "Endangered orangutans offer a new evolutionary model for early humans." ScienceDaily. ScienceDaily, 13 December 2011. <www.sciencedaily.com/releases/2011/12/111213203319.htm>.
Dartmouth College. (2011, December 13). Endangered orangutans offer a new evolutionary model for early humans. ScienceDaily. Retrieved December 19, 2014 from www.sciencedaily.com/releases/2011/12/111213203319.htm
Dartmouth College. "Endangered orangutans offer a new evolutionary model for early humans." ScienceDaily. www.sciencedaily.com/releases/2011/12/111213203319.htm (accessed December 19, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Friday, December 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Kids Die While Under Protective Services

Kids Die While Under Protective Services

AP (Dec. 18, 2014) As part of a six-month investigation of child maltreatment deaths, the AP found that hundreds of deaths from horrific abuse and neglect could have been prevented. AP's Haven Daley reports. (Dec. 18) Video provided by AP
Powered by NewsLook.com
Dads-To-Be Also Experience Hormone Changes During Pregnancy

Dads-To-Be Also Experience Hormone Changes During Pregnancy

Newsy (Dec. 18, 2014) A study from University of Michigan researchers found that expectant fathers see a decrease in testosterone as the baby's birth draws near. Video provided by Newsy
Powered by NewsLook.com
Prenatal Exposure To Pollution Might Increase Autism Risk

Prenatal Exposure To Pollution Might Increase Autism Risk

Newsy (Dec. 18, 2014) Harvard researchers found children whose mothers were exposed to high pollution levels in the third trimester were twice as likely to develop autism. Video provided by Newsy
Powered by NewsLook.com
UN: Up to One Million Facing Hunger in Ebola-Hit Countries

UN: Up to One Million Facing Hunger in Ebola-Hit Countries

AFP (Dec. 17, 2014) Border closures, quarantines and crop losses in West African nations battling the Ebola virus could lead to as many as one million people going hungry, UN food agencies said on Wednesday. Duration: 00:52 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

More Coverage


Starving Orangutans Might Help to Better Understand Obesity and Eating Disorders in Humans

Dec. 13, 2011 New research examining how endangered Indonesian orangutans – considered a close relative to humans -- survive during times of extreme food scarcity might help scientists better understand eating ... read more

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins