Sometimes we get letters here at Moment of Science asking whether psychics are for real. Well, despite the t.v. shows, there isn't any scientific evidence that psychic powers, such as mind-reading, actually exist. That doesn't prove they don't exist--just that, so far, there's no reason to think they do.
Still, the famous scientist and popular writer Isaac Asimov made an interesting observation about mind-reading once. Many people across the centuries have claimed they could read other people's minds. If this is true, Asimov points out, then mind-reading would be a fact of nature. It would be one of things that the human brain can do, just like dreaming or maintaining your body temperature. That would mean that mind-reading would have to be the result of evolution.
If, somehow, brains could read other brains directly, there would indeed be a very strong evolutionary advantage to it. In Asimov's example, even a simple version of mind-reading, such as a chicken being able to sense an approaching fox's brain as it thinks "food, food, food," would be a huge advantage! Animals of any species that could do rudimentary mind-reading should survive much better than ones that couldn't, and should pass on their mind-reading gene quite effectively.
Do you see the problem? The fact that there is a debate at all over whether mind-reading exists suggests that it doesn't. If it were a real phenomenon, versions of it should be widespread, the way normal vision is. We would expect it to be everywhere . . . not just in a few "special" people with nothing up their sleeves.