Giraffes are a species native to the planet Earth. When Ford Prefect was stranded on prehistoric Earth, he split up with Arthur Dent and went to Africa. Five years later, in Life, the Universe and Everything he claims to Arthur Dent to be ' single-handedly responsible for the evolved shape of the animal you came to know in later centuries as a giraffe.' He is apparently referring to the long neck of the animal, which he apparently stretched. When asked for further detail, he replied that it would 'disturb' you.