Tool use seems proper to some sort of intelligence, but not human intelligence. Corvids, chimps, raccoon etc. use tools too. So can we add anything to tool use that allows us to target tools as a sign of human intelligence?
One clue might be that, if some primitive hominid species used the same tool for 250,000 years, we’d also shy away from considering such a tool as a mark of human intelligence. Human tool use fits into the broader field of human art, and human art is essentially restless. Human art therefore divides into more and less primitive or developed and into diverse schools, themes, and styles. These all turn over at different paces, but they don’t change out of a mere exhaustion of the idea. We change the mode of the art even before we are sick of it and even before we have exhausted its possibilities. There is always an element in art of seizing its moment, and as soon as it ceases to do so it becomes either a museum piece or a sort of absurdity.
Human art marks out a new sort of behavior in relation to a new sort of environment, and so can be seen as meta-biological. It is responding to an environmental pressure, but one that comes from a meta-natural environment. It is this sort of environment that makes Gothic Cathedrals give way to Baroque ones, or jazz give way to rock or novels give way to whatever is coming after them. On a swifter moving current, it makes styles and fashions pass too quickly for most to keep up with them. One can see similar changes even in pure tools: handsaws, hammers, etc. that have a sort of fashion and development of their own, and not just one responding to development. Computers too change far more often than is necessary for the sort of uses most of us put them too. One can only get so far trying to explain this by economic factors – there is also the pure desire for change as such.
Are tools and art are part of us. They are things we find and express ourselves in. The restlessness we have with them arises from their inadequacy to exhaust this role, and so we find ourselves with a continual need to go beyond the tools we use and the art that speaks to us. Even where the same tool gets used over time, it shifts its sense over that time. We find ourselves saying something different to the world if we use a 2001 Toshiba Satellite in 2014 than if we are using it in 2002. It place in the meta-biological environment changes, even if our use of it does not.
And so when we make tool use the mark of human intelligence, we seem to be gesturing at developmental tool use, which is only one subset of our restlessness with all of or art, arising from its unstable and changing existence both in, and in response to, the meta-biological environment that human being find themselves inhabiting alone.