Quoting Terry's example:

"The giraffe appears to have grown a long neck for the purpose of reaching higher into the trees for its food"

That sentence is adequate for anyone with an understanding of Darwinian evolution theory. To them, the use of the word 'purpose' is simply a convenient linguistic device. Languages contain many other examples.

For those who want to split linguistic hairs, however, here's an alternative without the word 'purpose':

"The process of evolution has resulted in the long neck of the giraffe, by virtue of the fact that it enables it to survive by reaching higher into the trees for its food."

"Time is what prevents everything from happening at once" - John Wheeler