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 Researchers develop eco-friendly, 4-in-1 catalyst
25.04.2017 | Brown University

nachricht Transfecting cells gently – the LZH presents a GNOME prototype at the Labvolution 2017
25.04.2017 | Laser Zentrum Hannover e.V.

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

NASA's Fermi catches gamma-ray flashes from tropical storms

25.04.2017 | Physics and Astronomy

Researchers invent process to make sustainable rubber, plastics

25.04.2017 | Materials Sciences

Transfecting cells gently – the LZH presents a GNOME prototype at the Labvolution 2017

25.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>