From Arnold Broese:

Re: Rock-throwing zoo chimp stocked ammo in advance: study (March 10): The conclusion that this monkey “planned” ahead, is too hastily jumped at. As humans we tend to view the thought processes of other species as similar to our own. A squirrel collecting nuts for the winter is not employing a conceptual (abstract) idea of the future, but is rather responding to inner drives which interact with the environment.

In the case of the monkey, the association of stones with safety and self protection, is enough to inspire collecting a pile. Animals live on the perceptual level, not the abstract level. They can see two stones, but cannot grasp the concept “two”. In the same way, the monkey associates stones with protection on the perceptual level. However, to jump to the conclusion that the monkey has applied an abstract thought such as “future”, is not warranted when the simple explanation of association will suffice.

The day that another species is able to count in the abstract, such as consistently being able to fetch the required number of items, is the day it will have been proved that animals can think in concepts.