I think its very likey thats it is so. Scientist are still searching for the missing links perhaps they are looking in the wrong direction, they should look upwards no less.
But I will say that opposable thumbs has come hand in hand (no pun intended) with our physical evolution without these we could only contemplate what it would be like to build ourselves a better home.
Stef
P.S that link is a great read
http://www.agoracosmopolitan.com/hom.../26/01340.html 