Evolution alone does not explain the length of the giraffe's neck which is also related to its way of feeding, up or down. The giraffe diet is not limited to tree leaves and giraffes keep moving to find food. They graze grass while moving and cover such distances that they are the only animals to ruminate while walking. Their long neck give them an additional advantage : it can sweep very large areas (6.4ft i.e 5m in diameter) while advancing in a straight line, therefore spending as little energy as possible…