Giraffes

[Waterwolf]

If giraffes evolved long necks to eat the leaves from the tops of trees, why did they need to do so?

[equipshadow]

according to my knowledge, it is true that they need long neck for eating the leaves from top of the tree, as long as I remember of Darwin's reseaching, they didn't have long necks when they were in primal age of earth, but like all the other mammal and creatures on the earth, they needed to develop that way...

[equipshadow]

I'm not sure if this related to Darwin's researching, as far as I remember it is. and probably baby giraffes were eating leaves from bottom of the tree..

[incitatus]

It's an ecological niche. All animals are in competition for food sources. Lots of other animals can eat from lower branches, but only giraffes (and elephants by a different mechanism) can eat the top leaves. Acacia trees defend themselves on sides and bottom with big thorns, which is another incentive.
Incidentally, evolution works by mutation then dieback ... so the giraffes didn't "see the need" to grow long necks, then change to do it, they changed at random, then it turned out that the ones with long necks had an advantage, didnt starve, bred succesfully etc. Slowly this leads to speciation.