Background
A small, nocturnal, solitary forager
Grey mouse lemurs are small arboreal primates, that only occur in the wild on Madagascar. They are a nocturnal primate species, meaning that they are active during night time. Additionally, they are solitary foragers that primarily eat fruits, insects, tree gum and sugary secretion of certain insect larvae. Their short life span with early maturity and their small body size in relation to their relatively larger brains, makes them an interesting animal to study primate brain evolution.
Using cognitive traits in the wild
As you may already know, cognitive abilities in animals are valuable to utilize information from their environment. As a small feeder with a rather generalized diet, grey mouse lemurs use various cognitive abilities for their foraging.One basic cognitive ability is problem solving, which can be defined as the process of finding solutions to complex issues. In the wild, grey mouse lemurs use their problem solving skills to gain access to new food resources or to avoid predators.
Another cognitive ability may be inhibitory control. This is the ability to choose a more effective response over a more direct but ineffective one. Inhibitory control is necessary, for example, to refrain from eating a fruit that is not ripe yet, or resisting the temptation to eat in the presence of a predator!
Lastly, causal understanding requires an individual to understand how and why a particular event can lead to another. In grey mouse lemurs, causal understanding may be necessary to develop new foraging strategies. In other primate species this has been seen by an individual seeing a hard fruit or nut fall from a high tree and break open, and then proceeding to do this itself.
Understanding the within-species variation in cognition
In order to get a better understanding of these traits, it is important to know what variables can influence a within-species variation in cognition. These variables may include sex and age, but also a previous experience with cognitive tests may predict this within-species variation in cognition.
Captivity vs. the Wild
It can be rather challenging to study grey mouse lemur cognition in the wild and specifically to obtain specific information about their age, experience or maternal origin. On the other hand, there might also be differences in cognition between wild and captive animals, since captive born animals are usually considered to be bolder and have a higher exploration rate. This could mean that captive grey mouse lemurs would thus have better cognitive abilities than wild grey mouse lemurs, right? This is why I also compared my data from captive grey mouse lemurs to those from a wild lemur population!
Altogether, the aims of this study were to (1) determine the cognitive abilities in captive grey mouse lemurs in a problem solving, inhibitory control and causal understanding task, (2) assess whether variation in performance could be explained by sex, age or previous experience, and (3) compare the cognitive abilities in the captive grey mouse lemurs to their wild conspecifics.