Although rare, albinism has been observed in almost every vertebrate species on earth and wild animals persist in nature even with this seemingly adverse condition. Albinistic animals have been recorded and studied since Carolus Linnaeus in the mid-1700s. A number of comprehensive lists of albino animals observed in the wild were published in the mid-1900s and numerous articles continue to be published today. Albinism can be displayed for a number of reasons aside from inheritance including genetic mutations, diet, living conditions, age, disease, or injury. Albinistic traits can vary and individuals are usually classified as true albino, partial albino, or leucistic. Albino animals demonstrate both positive and negative responses to their albinistic characteristics.