“A camel never travels beyond its normal daily mileage or carries more than a prescribed load. They are not so fast as horses for which they have an inborn hatred. Camels can endure thirst for four days and, when they have an opportunity to drink, fill themselves to make up for the time they have gone without and for their future needs; they stir up the water by trampling in it, otherwise they do not enjoy their drink. Camels live for fifty years, some even for a hundred, although even camels are liable to contract rabies.”

(Pliny the Elder in Book VII of Natural History; p. 117 in John Healy’s Natural History: A Selection.)