Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Experiments reveal startling insights into lemur intelligence

13.05.2004


Such research could offer important evolutionary insights into the nature of intelligence in primates



Until now, primatologists believed lemurs to be primitive, ancient offshoots of the primate family tree, with far less intelligence than their more sophisticated cousins, monkeys, apes and humans. But at the Duke University Primate Center, with the gentle touch of his nose to a computer screen, the ringtail lemur called Aristides is teaching psychologist Elizabeth Brannon a startling scientific lesson -- that lemurs are, indeed, intelligent creatures.

Brannon is using touch-screens, Plexiglas boxes holding raisins and buckets hiding grapes to establish that ringtails such as Aristides and his mongoose lemur cousins possess a surprising ability to learn sequences of pictures and to discriminate quantities. While Brannon’s work is still only at a preliminary stage, its initial results lead her to believe that such studies could mark the dawning of a new appreciation of lemur intelligence.


Such research could offer important evolutionary insights into the nature of intelligence in primates, Brannon said, since lemurs are living models for the ancient primate mind. "Prosimians," including lemurs and related species split off from the primate line some 55 million years ago, evolving independently from the line that led to anthropoids and humans.

"One of the main threads of my research has been to understand how the human mind became so sophisticated numerically," said Brannon, who is an assistant professor of psychological and brain sciences and a member of Duke’s Center for Cognitive Neuroscience. "A big issue is whether primates have specific adaptations for such cognitive abilities that differ from other animals. And prosimians are a great model for these basal primate adaptations."

Brannon admits that she began her studies of lemurs -- supported by funds from the Primate Center -- with little hope of success. For one thing, lemurs show little of the sophisticated perceptual abilities, curiosity and interest in manipulation that would indicate that they would actively participate in experiments.

"The little bit of research that’s out there suggests their learning capacities are not as sophisticated as those of monkeys," said Brannon. "So initially, I thought it very unlikely that I was going to get any cognitive experiments to really work with them."

For example, she said, studies of ringtail social groups show that even though the animals interact with one another, they don’t seem to have as much knowledge of social relationships between the other animals in their groups, compared with monkeys and apes.

But the lemurs surprised her. When she and her undergraduate student researchers began to offer ringtails the chance to use a touch-screen to recognize images for a sugar-lump reward, the animals -- literally -- jumped at the chance.

"The ringtails live in social groups, which could be distracting, and they’re completely free to just ignore us and the apparatus. But despite these possible complications, we found they would completely voluntarily come over to the screen and participate."

Sometimes, the lemurs even competed with one another. "Occasionally, one animal would come over and finish the sequence started by another to get the reward," said Brannon.

Unlike monkeys and apes, who will explore objects out of curiosity, lemurs only work for food, said Brannon. But they will work. "If a task involves a food reward, they can be amazing," she said. "They’ll work for a couple of hundred trials because they want these sugar pellets, even though we do not deprive them of food in any way."

The touch-screen studies have involved asking the animal to remember the order of appearance of random images by touching them in order when they reappear as a group. So far, Brannon and her students have found that the animals do show a systematic learning ability, decreasing the time it takes them to learn the order of successive sets of images.

"This is a capability that pioneering primatologist Harry Harlow termed ’learning to learn,’" said Brannon. "It shows that the animal is actually learning some kind of strategy above and beyond what they’re learning about the individual pictures in a given set."

The animals do show a difference in interaction with the screen that reflects their more primitive ability to manipulate objects with their hands, said Brannon. "While monkeys will use their fingers, the ringtails use their nose or mouth to touch the screen, sometimes kind of kissing it."

In another experiment that explored lemurs’ numerical ability, Brannon and her students presented animals with a two-trayed box containing different numbers of tasty raisins or grapes in each tray. The animals were allowed to access only one of the trays. While the animals did show an ability to recognize larger quantities, found the researchers, they were not mathematical geniuses.

"We found that the lemurs were generally motivated to choose the larger quantities, but they didn’t show a huge bias in favor of the larger amount," said Brannon. "In fact, when the two quantities were very close in number, they aren’t too good at choosing the larger one -- but this general pattern of increasing performance as the difference between the two quantities increases is exactly what we see in rhesus monkeys and a wide range of other animals."

In another pilot study, in collaboration with postdoctoral research associate Kerrie Lewis, the researchers tested whether mongoose lemurs would search longer for two grapes hidden in a bucket after they’d seen two go in compared with when they’d only seen one go in. "We’re using their search time as a measure of whether they’ve perceived the number of food items that have actually gone into the bucket," said Brannon. So far, she said, it does appear that the lemurs recognize the difference between one and two grapes going into the bucket.

All of the lemur studies represent only the tantalizing beginning of a promising new research pathway, said Brannon.

"We’ve only been studying ringtails and mongoose lemurs so far," she said. "But our hope is to study many different prosimian species at the Primate Center, taking advantage of the fact that the center has so many different species with such an incredible diversity in sociality and ecology.

"For example, ringtail lemurs are probably the most social of the prosimians. And we’re interested in whether such social structure may have selected for certain kinds of numerical or other conceptual abilities," she said.

"Our broad goal is to determine whether there are any significant differences in numerical cognition among different prosimian species and then trying to correlate those differences with some aspect of their social structure or their ecological niche," said Brannon.

Dennis Meredith | Duke University
Further information:
http://www.dukenews.duke.edu/news/experiment_0504.html

More articles from Life Sciences:

nachricht One step closer to reality
20.04.2018 | Max-Planck-Institut für Entwicklungsbiologie

nachricht The dark side of cichlid fish: from cannibal to caregiver
20.04.2018 | Veterinärmedizinische Universität Wien

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

Im Focus: Like a wedge in a hinge

Researchers lay groundwork to tailor drugs for new targets in cancer therapy

In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Magnetic nano-imaging on a table top

20.04.2018 | Physics and Astronomy

Start of work for the world's largest electric truck

20.04.2018 | Interdisciplinary Research

Atoms may hum a tune from grand cosmic symphony

20.04.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>