Our halux (big toe) will gradually shrink, and the third toe will become the longest, due to the shape of shoes.
What? It's happening now, and has been termed new halux (it's a word Spellcheck And so is that!).
Probably not what you were looking for.
What might happen in the future: As we gain the ability to edit genes (hypothetically leading offspring to inherit the edits), there might be groups of humans who branch off with flying humans, photosynthetic humans, merpeople, etc. However, a mutant gene may occur, leading to a bigger/more efficient brain or other body part (ohh...that sounds dirtier than intended) which would allow high survivability, such as maybe not needing to use as much oxygen at a higher atmosphere, leading the changed individuals to survive longer. Man has, and will continue to adapt to their enviornment. Also, it will be a gradual change, (like new halux, the most worthless thing around) not everyone waking up with wings. However, that could be pretty cool.
Romidude said:
I believe what is used most are the parts that will change the most during evolution, our penises and fists will evolve and become much more advanced, while our brains will wither away.
It's been scientifically proven that behavior has no impact on evolution. Evolution impacts genes or mutation. While a bigger penis may lead to more reproduction=more children with trait, that will lead to evolution as the gene works. But children won't have gigantic hands because they have a father/mother who punched a lot of people.