Chimpanzees eat smart when it comes to mealtime

Mar 21, 2013 by Amy Patterson Neubert
Bryce Carlson, a Purdue assistant professor of anthropology who studies primate ecology and nutrition in human evolution, found that chimpanzees watch what they eat and when, which may show that these primates are giving some thought to the quality of their food. Data regarding the chimpanzees and two species of saplings were collected from Ngogo in Uganda's Kibale National Park. Carlson's findings are published in the American Journal of Primatology. Credit: Bryce Carlson

Chimpanzees watch what they eat and when, which may show that these primates are giving some thought to the quality of their food, according to Purdue University research.

"There is an association between the time of day primates eat certain resources and the nutritional quality of those resources, suggesting consumption may track nutrient content," said Bryce Carlson, an assistant professor of anthropology who studies primate ecology and nutrition in human evolution. "We can't say for sure if are consciously selecting the leaves when is greatest, but this correlation presents an intriguing hypothesis to explain feeding behavior in this and mechanisms for ingestive behavior in general."

The study's results are published in the April American Journal of Primatology, and this work was funded by the National Science Foundation and L.S.B. Leakey Foundation. Carlson, who is a member of Purdue's Ingestive Behavior Research Center, is studying the of wild chimpanzees as part of his research on the history of diet in . These primates, which live in forest areas of Africa, are part of the hominidae family that also includes humans, gorillas and orangutans. It is estimated there are 300,000 chimpanzees in the wild.

Chimpanzees, whose diet is composed of fruit, leaves, plant stalks, roots, insects and other , frequently consume various leaves at the end of the day. Other researchers have proposed the animals prefer eating leaves at that time to feel full and facilitate greater overnight, or that this daily eating pattern results from , where chimpanzees typically spend late afternoons in smaller foraging groups on the ground where these leaves are found.

The Celtis africana is a smaller tree common throughout the Ngogo chimpanzee habitat, and it is among primate's food sources. Credit: Bryce Carlson

"But we know there is a correlation between and daily feeding patterns for other animals, such as domesticated sheep," Carlson said. "So we wanted to take a closer look at chimpanzees by comparing the primates' feeding habits to the nutritional composition of these leaves throughout the day."

Data regarding the chimpanzees and two species of saplings, Pterygota mildbraedii and Celtis africana, were collected from Ngogo in Uganda's Kibale National Park. The Ngogo chimpanzee community is the largest observed in the world - more than 180 animals - and has been actively studied since 1995.

Daily feeding observations from 2002-2011, made primarily during the dry season months of June through August, of 41 adult male chimpanzees were analyzed for eating patterns. These were compared to nutrition samples from Pterygota mildbraedii and Celtis africana. Leaf samples were taken from different saplings and at various feeding times during the day.

Pterygota mildbraedii is a very large tree, common throughout the Ngogo chimpanzee habitat. The chimpanzees, however, eat young leaves of the saplings found near the forest floor. This study found that the leaves' hemicellulose - a more digestible fiber - and nonstructural carbohydrates - simple sugars and starch - increased 15 percent to 100 percent, respectively, from morning to evening. Cellulose and lignin, which make the leaves more difficult to digest, also decreased by day's end. Celtis africana is a smaller tree than Pterygota, the saplings of which contain many thin branches and small leaves. The sugars in this plant's leaves were found to double from morning to late afternoon.

"If these sugars or total non-structural carbohydrates are increasing, then the leaves are returning more calories late in the day," Carlson said. "At this time, they may taste sweeter, and the chimpanzees may then learn and adjust their feeding behavior accordingly. We know they use vision, texture, taste and smell to gauge when to eat fruit, so it's understandable to think they may do the same with leaves."

Carlson's research will continue to focus on diet for wild chimpanzees and human ancestors.

"Questions about what humans are eating today and why are important as our growing world population increasingly struggles with malnutrition tightly linked with quality of life, morbidity and mortality," Carlson said. "Evolution for any species is related to, and even driven by, food availability and quality, so the more we learn about our long history with food, the better able we are to make individual and population level recommendations for consumer behavior today and years to come."

Explore further: Male monkey filmed caring for dying mate (w/ Video)

More information: Diurnal Variation in Nutrients and Chimpanzee Foraging Behavior, i>American Journal of Primatology, 2013.

ABSTRACT
Primate feeding behavior varies over long (e.g. weekly, seasonally, yearly) and short (e.g. hourly) scales of times due to changes in resources availability and the nutritional composition of foods. While the factors that affect long-term changes in feeding behavior have received considerable attention, few data exist regarding what drives variability in feeding behavior over the course of a single day. To address this problem, we investigated diurnal variation in chimpanzee feeding on the leaves of two species of saplings, Pterygota mildbraedii, and Celtis africana, at Ngogo, Kibale National Park, Uganda. Specifically, we related short-term changes in chimpanzee feeding behavior on these leaves to diurnal variation in their nutrition composition. Results showed that chimpanzees fed on the leaves of both saplings more in the evening than they did in the morning. The nutritional quality of leaves also improved over the course of the day. Concentration of cellulose and lignin were lower and total non-structural carbohydrates (including sugars and starch) were higher in the evening for P. mildbraedii, and sugars were higher in the evening for C. africana. These data suggest that chimpanzees consume these resources when their quality is highest, and consequently, may track the nutrient composition of their foods over very short periods that span only a few hours. In the future, foods collected for analyses must control for time of sampling to ensure biologically meaningful assays of nutrient composition.

Related Stories

Chimpanzees use sex tools

May 05, 2010

(PhysOrg.com) -- Many animals are known to use tools, but chimpanzees (our closest living relatives) show the most varied and complex use of tools, and the males in one group of chimps have even been observed ...

Chimps self-medicate under human pressure

Jun 21, 2012

Chimpanzees living in small fragments of forest close by people and farm animals are turning in increasing numbers to natural remedies in an effort to deal with their stressful and disease-prone existence, ...

Recommended for you

Male monkey filmed caring for dying mate (w/ Video)

Apr 18, 2014

(Phys.org) —The incident was captured by Dr Bruna Bezerra and colleagues in the Atlantic Forest in the Northeast of Brazil.  Dr Bezerra is a Research Associate at the University of Bristol and a Professor ...

Orchid named after UC Riverside researcher

Apr 17, 2014

One day about eight years ago, Katia Silvera, a postdoctoral scholar at the University of California, Riverside, and her father were on a field trip in a mountainous area in central Panama when they stumbled ...

In sex-reversed cave insects, females have the penises

Apr 17, 2014

Researchers reporting in the Cell Press journal Current Biology on April 17 have discovered little-known cave insects with rather novel sex lives. The Brazilian insects, which represent four distinct but re ...

Fear of the cuckoo mafia

Apr 17, 2014

If a restaurant owner fails to pay the protection money demanded of him, he can expect his premises to be trashed. Warnings like these are seldom required, however, as fear of the consequences is enough to ...

User comments : 0

More news stories

Biologists help solve fungi mysteries

(Phys.org) —A new genetic analysis revealing the previously unknown biodiversity and distribution of thousands of fungi in North America might also reveal a previously underappreciated contributor to climate ...

Researchers successfully clone adult human stem cells

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...

Airbnb rental site raises $450 mn

Online lodging listings website Airbnb inked a $450 million funding deal with investors led by TPG, a source close to the matter said Friday.