Tool use is just a trick of the mind

there used to be a time when people thought only humans were capable of tool use.

Judging by some people I know, that applies to cell phones as well, but in a more permanent sense.

That's pretty interesting, though.

It does, absolutely.

That's part of the concept. When you first use something such as a writing instrument or a mobile phone, your brain creates new pathways and instructions to treat this tool as just another part of your body. Given enough time and enough strengthening of these new pathways, things become "second nature". Typing is an excellent example.

Also, scientists now have a very good idea where to look for the mutation that caused our ancestors to develop the capacity for tool use. It is a simple, yet extraordinary change.

Another interesting effect is demonstrated by a post I read over at Slashy.

This is the example I was taught in psych class. Use your finger to apply pressure to your table. You feel pressure in the tip of your finger. Now use a pencil to apply pressure to your table. You then feel pressure at the tip of the pencil, and not in your fingers where you hold the pencil.

Note that, if you make an effort, you can feel the pressure on your fingers from the pencil. But the natural experience is to feel pressure in the pencil, as if it were part of your body. What this in fact proves is that the brain can make you 'feel' sensations anywhere, and not just in your body.

I tried it. Gave me the heebie jeebies for about a half a second when I tried to focus on where it was coming from

I tried it with the pencil, I found nothing, save the pressure of my fingers on the pencil...

I suppose you aren't a human, then.