Jonathonm980
It wasnt optional for the apes to evolve.. they didnt say "I need lungs. lets go to the genie shop and get some" no, it just happened so, if we were to evolve a little fairy wouldnt come down and say "would you like a third leg?" It would just happen
Thats correct, evolution happens whether you like it or not
The rest of your statement makes much less sense. Of crouse not, in order for the apes to live they needed to have lungs before hand, I doubt they used diffusion.
Evolution gives you what you need to survive in your envrionment, you do not need a 3rd leg, therefore, you will not get one. And it wouldn't just happen, if we did need a 3rd leg, the next generation wouldn't pop out with one fully formed, it would would take a whole lot of time.