Interesting point. I wonder if our minds couldn't handle both. We are kind of a use-it-or-lose-it system, so not having to remember a whole bunch of stuff doesn't necessarily free up the resource; rather we just lose the resource - unless it's the exact same resource that does both tasks. Then it just specialises differently.

Take someone that speaks two languages fluently. They are just as fluent in each language as someone that only speaks one of each. That's probably not a very good example :)

ah, who knows. All I know is I can't spell as well as when I was a kid haha.