Fruits are good for maintaining a healthy body as well as a healthy mind, is a fact that almost everyone knows. A research conducted to understand the genesis of intelligence in the primates also confirms the same. Researchers have found that the lemurs gorging heavily on fruits show better cognitive abilities than the lemurs that feed on a variety of food such as leaves, insects, seed and so on. The finding supports the notion that eating seasonal fruits or fruits that are difficult to get, gives certain cognitive edge to lemurs.
Researcher Alexandra Rosati of Yale University and Kerri Rodriguez and Brian Hare from Duke University, studied 64 lemurs from five different species that were kept in captivity at Duke Lemur Center. The species chosen for the study were red ruffed and black and white ruffed lemurs that included mainly fruits in their diet, Coquerel sifakas eating leaves, ring tailed and mongoose lemurs whose diet compromises fruits, seeds, insects, flowers and leaves.
In two experiments, the lemurs were tested for their ability to remember the spot in the boxes and mazes where food was concealed. During the first experiment, the lemurs were tested for their ability to find the food location that was concealed in either of the two arms of a T shaped maze. And discovered that only the ruffed lemurs, who preferred eating fruits were able to remember the arm of the T shaped maze and also identified the exact location of the food, after a week’s time.
The second experiment was conducted to test if the lemurs could remember the exact point of food or instead they retain the turns they took to arrive at the point. The researchers placed the primates in one wing of symmetrical cross shaped maze and were observed while they searched for the concealed food. After 10 minutes the lemurs were placed in another wing of the maze and were again observed while they unravel their way to reach the food.
The ruffed lemurs again excelled in the quest to find the exact spot in the maze, though some new turns were introduced in the search. Researchers based on the findings concluded that the ruffed lemurs retain the exact food spot and not the turn they took to arrive at the spot. While the other lemurs that were part of the study used and demonstrated a mix of both the approaches.
Another experiment to test whether lemurs are capable of remembering several locations was also conducted. These experiments explain that the ability to recall as seen in rugged lemurs are inborn and not learned as the lemurs held in captivity do not have to search for food as they would when in the wild, one of the researchers said.
The researchers are of the view that fruits mainly figs consist 90 percent of the diet of ruffed lemurs that are found in Madagascar. Figs are eaten when ripe and are available for a short duration on the tree and the next tree laden with ripe figs may be at some distance. Due to which lemurs need great memory to remember where they can find these figs in different seasons. On the contrary, Coquerel’s sifakas who feed on leaves which are easily available all through the year. The second and third ranked ringed tailed and mongoose lemurs respectively in the memory test, eat a variety of things, commonly available in the vicinity at that point of time.
Therefore, it can be said that cognitive intelligence in the lemurs originated because they wandered in search of food that was not available at one place round the year. And so developing the recalling ability helps the lemurs feeding on a special diet, to survive in the wild whereas others did not develop the skills as they had many options available around and need no effort in procuring them.