APPARENTLY WE STILL DON’T KNOW WHY THE GIRAFFE GOT ITS LONG NECK. I like this post from the University of Waikato blog (in New Zealand) because it begins with Kipling and quotes a phrase I remember recurring in the stories: “great grey green greasy Limpopo River”.
The post recounts the accepted story that the long neck had evolved as an adaptation which allowed giraffes to browse high in the trees, using a resource not available to other, shorter-necked competitors. The post says: “The late Stephen Jay Gould (1996) characterised this as a fairy story that Darwin was far too smart to tell, but which entered our high-school texts as a classic case nonetheless.” One problem for this theory is that “a study showed that rates of giraffe feeding peaked at intermediate heights equal to approximately 60% of adult giraffe height.”
Another theory is that sexual selection gave an advantage to males with long necks. However, a 2009 study of 38 giraffes showed that there were minimal morphological differences between the sexes, suggesting that long necks did not give male giraffes an advantage in sexual competition.
So it appears that there was evolution in neck sizes—supported by the fossil evidence of the intermediate species—but there is no established reason for why a long neck would be advantageous.