Tool use, like many cognitively complex behaviors and capacities before it, was initially believed to be a skill unique to humans. This is no longer the case; both anecdotal and experimental examples of tool use are fairly prevalent within certain branches of the animal kingdom.
Of course, what does and does not qualify as tool use is entirely dependent on how we define the term. One definition of tool use is broader, only requiring that the user manipulate an object in the environment in such a way as to attain a goal. Another definition further specifies that the object must not be attached to the environment.
In the first two photos below, Pumpui is seen scratching part of her body with an environmental object. While both photos would qualify under the former definition, only the photo of Pumpui scratching her ear with the sugarcane would qualify under the latter definition. Because living trees are attached to the environment and are therefore disqualified from being tools under the latter definition, whether or not they are manipulated to attain a goal becomes irrelevant.
Let’s consider a less explicit example of tool use.
According to the more stringent definition, Bo is indeed using a tool—the dirt and grass on her back—in the photo below.
This qualifies because a) she used her trunk to deposit it there, b) the debris is an environmental object which is neither attached to her body nor to the ground, and c) the deposition of the debris on her back is advantageous to her; it offers both protection from the sun and from flying insects.
The primary reason this example of tool use may be considered borderline has to do with timing. In the previous examples in which Pumpui was scratching an itch, the time lapse between tool usage and received benefit was negligible. Here with Bo, however, the benefits of the debris on her back are not immediately received—at least not fully. The length of this interval is noteworthy. Timing has not completely escaped the attention of animal behaviorists in attempts to define tool use with varying degrees of exclusivity. Some definitions do include temporal aspects, requiring the user to hold the tool during or just prior to usage. Here, any tool that is manipulated as a projectile (thrown, flung, spat, etc.) still qualifies. Addressing this time interval, however, still fails to account for the difference between immediate short-term benefits (scratching an itch) and “immediate” long-term benefits (skin protection).
It is important to note that it is not necessarily clear—especially in anecdotal cases— whether the tool user actually understands the causal relationship between the use of the tool and the positive effect that results. Still, the case of Pumpui scratching her ear seems to suggest a causal awareness; she does not seem to be using the sugarcane mindlessly, but rather for good reason. Returning to the case of Bo and the deposit of debris on her back, the implication of causal awareness is arguably weaker because the benefits are not received in the short-term. The impulse Bo has to fling debris onto her back could be derived from an innate or biological urge, as opposed to an awareness that the debris offers relatively long-term skin protection.
Another important factor to consider in any conversation about tool use as a demonstration of advanced cognition, is that tools are used out of necessity. Regarding tool use, intelligence does not necessarily correlate to tool complexity or even the range of contexts in which they are utilized. Certainly, many primate and bird species not only use tools in wide-ranging contexts, they are also known to make complex modifications to tools prior to their use. But necessity truly is the mother of invention. Elephants—with their large, strong bodies and their precision trunks—simply might not require tools very often. Furthermore, the tools they do need may be more readily available in their environment, requiring little to no modification.
Here’s the bottom line. Definitions vary widely as to both what constitutes a tool and what constitutes legitimate usage. Elephants can and do use tools when tools are necessary, and—in some cases more than others—an implicit understanding of cause-and-effect seems to serve as the motivation behind such tool use.