The earliest known ancestor of deer is Diacodexis, which lived during the early Eocene period 50 to 55 million years ago. This creature was nearly the size of a rabbit and possessed the talus bone characteristic of all modern even-toed ungulates.
The moose is the largest extant deer standing nearly two meters tall at the shoulder and weighing up to 700 kilograms. The northern pudu is the smallest deer in the world reaching merely 40 centimeters at the shoulder and weighing less than four kilograms.
Indigenous representatives of deer exist on all continents except Antarctica and Australia. Africa has only one native deer called the Barbary stag confined to the Atlas Mountains while other species like caribou and moose inhabit circumpolar regions across North America and Eurasia.
Deer appear in art from Paleolithic cave paintings onwards including some 90 images of stags at Lascaux in southwestern France dated 17,300 years old. These ancient depictions confirm that humans have interacted with deer for tens of thousands of years.
License sales for deer hunting generate approximately $700 million annually according to a 2006 survey by the U.S. Fish and Wildlife Service. Overall big game hunting generates approximately $11.8 billion annually in travel and equipment expenditures within the country.