the neck of a giraffe can be explained by natural selection. less competition for leaves at those heights on a tree gave giraffes a better chance of survival.
what can’t be explained is how/why a fish evolved into a giraffe. that’s where evolution makes the leap to untestable theory.
Change can be explained in number of ways, but those explanations are nothing but guesses. As I said before, there is absolutely no logical reason to presume that the giraffe survived better with a longer neck.
All we know for certain is that it is outnumbered by shorter necked ruminants and that it has managed to survive with a long neck. So why from that would anyone conclude that having a long neck gave it competitive advantage?
If you hand me fishing pole, I’ll fish with it. If you hand me a spear, I’ll hunt with it. If the giraffe had a mutation that resulted in an ever growing neck, then it ate leaves as a mechanism to cope, yet scientists continually presume that the giraffe needed to start eating leaves in order to survive.