I think I see what you are getting at. Well I think it is more Darwinian than that. I will use giraffes as an example they progressively got longer necks due to the fact that the ones with longer necks could reach the food on the higher branches. So when one with shorter neck can't get food it will die. But the ones that can reach the food (with longer necks) they live and reproduce passing on the favorable trait of a longer neck, which inturn passes into the offspring. Now the change isn't going to be to dramatic in 1-2 generations, when you wait 100's of generation you end up with current very long necked giraffes. Hope this makes sense.
But it is based on Darwins findings.


99' tropic green SVT
2558/2760
born on 08/06/99
KKM, resonator removed, B&M short throw, SHO shop y-pipe w/cat,
Pioneer deck, Boston Accoustics 10" rallys, MTX thunder amp