Can sex, age, or previous experience explain a within-species variation in grey mouse lemurs?

First, 88.2% of all lemurs were able to solve the problem solving test, which means that they managed to open at least one compartment of the food extraction box. Almost half of all individuals managed to even open all six wells within the fixed experimental time. However, none of the variables age, sex, maternal effect or previous experience predicted the variation in this task.

When looking at the results from the inhibitory control task (= cylinder task), only 8.8% of the individuals had zero incorrect trials. At the other end of the scale, 5.9% of all individuals had a score of 9 incorrect trials, which was also the highest amount of incorrect trials that occurred. Additionally, age predicted the within-species variation in inhibitory control, the older the animals were, the more incorrect trials they had.

When looking at the animals’ causal understanding from the string pulling task, 61.8% of the animals managed to pull the string and obtain the reward, thus succeeded in this task. When looking at the influence of the variables, sex predicted the within-species variation in causal understanding. Females had a significantly faster success compared to the males.

Do captive grey mouse lemurs have better cognitive abilities than wild ones?

For the problem solving task, as I mentioned before 88.2% of the captive lemurs managed to at least open one compartment and thus succeeded, whereas this percentage was 100% in the wild lemurs. This difference was also noticeable in the innovation speed and in the number of successes: Wild grey mouse lemurs were significantly faster than the captive ones and opened significantly more compartments than the captive animals.

In contrast, I found no difference between the captive and wild animals with regard to their inhibitory control.

Lastly, for the causal understanding, while only 61.8% of the captive grey mouse lemurs succeeded in the string pulling task, this value was 90.5% in the wild population. This difference in succeeding is reflected in differences in the success latency of the animals: Wild grey mouse lemurs were again significantly faster than the captive grey mouse lemurs.