PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

Apes unwilling to gamble when odds are uncertain

2010-11-30
(Press-News.org) DURHAM, N.C. -- Humans are known to play it safe in a situation when they aren't sure of the odds, or don't have confidence in their judgments. We don't like to choose the unknown.

And new evidence from a Duke University study is showing that chimpanzees and bonobos, our closest living primate relatives, treat the problem the same way we do.

In studies conducted at the Tchimpounga Chimpanzee Sanctuary in Republic of Congo and Lola ya Bonobo Sanctuary in Democratic Republic of Congo, researchers found the apes prefer to play it safe when the odds are uncertain.

Graduate student Alexandra Rosati and Brian Hare, an assistant professor of evolutionary anthropology, asked 16 chimps and 14 bonobos to make choices between two bowls of treats.

Though no dice or chips are involved, this kind of experiment is considered a "gambling game," Rosati said. The apes could choose between a safe bet that would always provide a food they liked somewhat less, peanuts, or a variable bet in which the payout could be either a highly-preferred big piece of banana or less-desirable cucumber slice.

The apes "gambled" by making a choice of one bowl or the other. They knew the odds before they chose because the experimenter showed them bowls with two potential outcomes, but then gave them only one. Depending on the contents of the bowls, there could be a 100 percent chance of receiving a banana, a 50 percent chance, or a 0 percent chance.

The apes readily distinguished between the different probabilities of winning: they gambled a lot when there was a 100 percent chance, less when there was a 50 percent chance, and only rarely when there was no chance.

In some trials, however, the experimenter didn't remove a lid from the bowl, so the apes couldn't assess the likelihood of winning a banana.

The odds from the covered bowl were identical to those from the risky option: a 50 percent chance of getting the much sought-after banana. But apes of both species were less likely to choose this ambiguous option.

They were willing to take the chance on the covered bowl when they knew the only alternative was food they didn't like (the cucumber), or no food at all. But, like humans, they showed "ambiguity aversion" -- preferring to gamble more when they knew the odds than when they didn't.

Given some of the other differences between chimps and bonobos, Hare and Rosati had expected to find the bonobos to be more averse to ambiguity, but that didn't turn out to be the case.

Researchers looking for the foundations of economic decision-making have been doing studies like this on a variety of species, but these two apes are the two species most closely related to humans, Rosati said.

"These results suggest that understanding how animals forage may be more complex than previously thought," Rosati said.

Decision-making matters to animals in the wild who have to make choices about which resources to pursue on the fly, without knowing if their choices will pay off. "It may be that different decision mechanisms come into play when animals are faced with choices when they have incomplete knowledge," Rosati said.

"These results also suggest that some of our human economic biases may be evolutionarily ancient, predating modern markets: chimpanzees and bonobos act just like us when faced with a primate slot machine," Rosati said.

### CITATION: "Chimpanzees and bonobos distinguish between risk and ambiguity," Alexandra Rosati & Brian Hare. Biology Letters, November 2010. doi:10.1098/rsbl.2010.0927

END



ELSE PRESS RELEASES FROM THIS DATE:

New tool to measure quality of patient care

2010-11-30
A national conversation continues about the best ways to improve both the quality of medical care and to contain costs. So far, developing quality measurements has focused on primary care or highly prevalent, chronic conditions such as asthma and diabetes. But what about brain disorders? To date, the number of measures that apply to neurologic care has been limited. The American Academy of Neurology (AAN), an association of more than 22,500 neurologists and neuroscience professionals, reached out to a group of neurologists to develop such a set of measurements. Led ...

Chemistry for greenhouse gases

Chemistry for greenhouse gases
2010-11-30
If fossil fuels burn completely, the end products are carbon dioxide and water. Today the carbon dioxide is a waste product, one that goes into the air — adding to global warming; or the oceans — acidifying them; or underground — with as yet unknown consequences. But it's not impossible, says Liviu M. Mirica, PhD, assistant professor of chemistry at Washington University in St. Louis, to drive things the other way, turning carbon dioxide into fuels such as methanol or hydrocarbons. Until now reversing combustion has been a loser's game, because making carbon dioxide ...

Declining energy quality could be root cause of current recession

Declining energy quality could be root cause of current recession
2010-11-30
An overlooked cause of the economic recession in the U.S. is a decade long decline in the quality of the nation's energy supply, often measured as the amount of energy we get out for a given energy input, says energy expert Carey King of The University of Texas at Austin. Many economists have pointed to a bursting real estate bubble as the initial trigger for the current recession, which in turn caused global investments in U.S. real estate to turn sour and drag down the global economy. King suggests the real estate bubble burst because individuals were forced to pay ...

Women with migraine with aura have better outcomes after stroke

2010-11-30
DALLAS, Nov. 29, 2010 — Women with a history of migraine headache with aura (transient neurological symptoms, mostly visual impairments) are at increased risk of stroke. However, according to new research reported in Circulation: Journal of the American Heart Association stroke events in women with migraine with aura are more likely to have mild or no disability compared to those without migraine. In a new analysis of the Women's Health Study involving 27,852 women over 13.5 years, researchers found those who have migraine with aura and who experience an ischemic stroke ...

Researchers demystify glasses by studying crystals

2010-11-30
TEMPE, Ariz. – Glass is something we all know about. It's what we sip our drinks from, what we look out of to see what the weather is like before going outside and it is the backbone to our high speed communications infrastructure (optical fibers). But what most people don't know is that "glass transitions," where changes in structure of a substance accompanying temperature change get "frozen in," can show up during cooling of most any material, liquids through metals. This produces "glassy states," of that material – exotic states that can be unfrozen and refrozen by ...

Heat wave deaths highest in early summer

2010-11-30
New Haven, Conn.—The risk of dying from a heat wave is highest when heat waves occur early in the summer and are hotter and longer than usual, according to a Yale study published in the journal Environmental Health Perspectives (EHP). During the first heat wave of a summer, the risk of mortality increases 5.04 percent, compared to 2.65 percent for heat waves that occur later in the summer. Michelle Bell, a co-author of the study and associate professor of environmental health at the Yale School of Forestry & Environmental Studies, said that people may be less accustomed ...

Drop in breast cancer rates directly tied to reduced hormone therapy

2010-11-30
In a new UCSF study of more than 2 million mammogram screenings performed on nearly 700,000 women in the United States, scientists for the first time show a direct link between reduced hormone therapy and declines in ductal carcinoma in situ (DCIS) as well as invasive breast cancer. The researchers saw such a striking decrease, they believe they also have uncovered indirect evidence that hormones promote breast tumor growth. The declines occurred in the age groups that most widely embraced then abandoned hormone therapy. For nearly a decade, postmenopausal women have ...

Scripps Research scientists redefine the role of plasma cells in the immune system

2010-11-30
La Jolla, CA – November 29, 2010 - For Immediate Release – A team of scientists from The Scripps Research Institute have uncovered a previously unknown regulatory mechanism in the body's response to eliminate pathogens, such as bacteria and viruses. The findings challenge a long-held dogma in the field of immunology and have potential implications for far-ranging topics from how vaccines should be administered to the origin of autoimmunity. The results of the study, led by Scripps Research Professor Michael McHeyzer-Williams, were published in the December issue of the ...

Vitamin D and calcium -- updated dietary reference intakes from IOM

2010-11-30
Vitamin D and calcium have been the focus of much research since the Institute of Medicine set nutritional reference values for them in 1997. Known as Dietary Reference Intakes, the values for these and other nutrients serve as a guide for good nutrition and provide the scientific basis for the development of food guidelines in both the United States and Canada. Updated DRIs for these two nutrients are presented in a new IOM report, Dietary Reference Intakes for Calcium and Vitamin D, which will be released on Tuesday, Nov. 30. INFORMATION: Details: Embargoed copies ...

People with sleep apnea at higher risk for aggressive heart disease

2010-11-30
CHICAGO – People with obstructive sleep apnea (OSA), a sleep disorder associated with obesity, have more non-calcified or "bad" plaque in their coronary arteries, according to a study presented today at the annual meeting of the Radiological Society of North America (RSNA). "Our study reveals that individuals with obstructive sleep apnea are prone to developing an aggressive form of atherosclerosis that puts them at risk for impaired blood flow and cardiovascular events," said U. Joseph Schoepf, M.D., professor of radiology and medicine and director of cardiovascular ...

LAST 30 PRESS RELEASES:

Sylvester Cancer Tip Sheet for October 2025

Three science and technology leaders elected to Hertz Foundation Board of Directors

Jump Trading CSO Kevin Bowers elected to Hertz Foundation Board of Directors

Former Inscripta CEO Sri Kosaraju elected to Hertz Foundation Board of Directors

Citadel’s Jordan Chetty elected to Hertz Foundation Board of Directors

McGill research flags Montreal snow dump, inactive landfills as major methane polluters

A lightweight and rapid bidirectional search algorithm

Eighty-five years of big tree history available in one place for the first time

MIT invents human brain model with six major cell types to enable personalized disease research, drug discovery

Health and economic air quality co-benefits of stringent climate policies

How immune cells deliver their deadly cargo

How the brain becomes a better listener: How focus enhances sound processing

Processed fats found in margarines unlikely to affect heart health

Scientists discover how leukemia cells evade treatment

Sandra Shi MD, MPH, named 2025 STAT Wunderkind

Treating liver disease with microscopic nanoparticles

Chemicals might be hitching a ride on nanoplastics to enter your skin

Pregnant patients with preexisting high cholesterol may have elevated CV risk

UC stroke experts discuss current and future use of AI tools in research and treatment

The Southern Ocean’s low-salinity water locked away CO2 for decades, but...

OHSU researchers develop functional eggs from human skin cells

Most users cannot identify AI bias, even in training data

Hurricane outages: Analysis details the where, and who, of increased future power cuts

Craters on surface of melanoma cells found to serve as sites for tumor killing

Research Spotlight: Mapping overlooked challenges in stroke recovery

Geographic and temporal patterns of screening for breast, cervical, and colorectal cancer in the US

Cannabis laws and opioid use among commercially insured patients with cancer diagnoses

Research Spotlight: Surprising gene mutation in brain’s immune cells linked to increased Alzheimer’s risk

Missing molecule may explain Down syndrome

Donor diabetes and 1-year Descemet membrane endothelial keratoplasty success rate

[Press-News.org] Apes unwilling to gamble when odds are uncertain