The main conlcusions of my project based on the results described in the results section are:

1. The degree of preferential hand use varied depending on the task the chimpanzees performed and between individuals, in other words, some tasks elicit stronger hand preferences than other:

This could be due to different sensory systems involved, as previous research has found that haptic tasks in chimpanzees elicit right hand biases, while more visual tasks elicit left hand biases. The degree of novelty has also been related to the strength of hand preferences, with novel tasks elliciting stronger biases. Finally, the body position adopted by the chimpanzees has been related with the strength of hand preferences, being more unstable positions the ones that elicit stronger biases.  

2. The degree of consistency in hand preferences varied between individuals:

 Chimpanzees  degree of  consistency in hand use across tasks is lower than the level found in humans.

3. There are no sex differences in either strength or direction of hand preferences for any of the tasks studied.

4. Manual digging occurs much more often than tool use digging:

This differences could be due to manual digging being a less demanding tasks than tool use digging, as it does not imply looking for and transporting tools. It could be that the task of digging can be easily solved manually so there is no need of using tools.

This sex differences could be explained by the higher persistance of females as diggers or because females are less strong than males and therefore need more time than males to retrieve buried objects.