Jouan & Rius / Aboriginal rock art showing sailing boat, Nanguluwur Gallery, Nourlangie Ranges, Kakadu National Park, Northern Territory, Australia

Jouan & Rius / Aboriginal rock painting, Art Gallery Cave, Carnarvon National Park, Queensland, Australia. The painting is believed to me more than 2000 years old and shows hands, boomerangs, emu feet and rock walla...

Juergen Freund / Ancient aboriginal Wandjina rock art in cave, Bigge Island, Western Australia

Richard Du Toit / Bushman rock art, 'Fallen Rock' site, Bushmans Kloof, Cederberg, South Africa

Owen Newman / Rock art / cave paintings, people, Namibia.

Claudio Contreras / Prehistoric rock art with depiction of Pronghorn antelope. Boca de San Julio cave, San Francisco Sierra, El Vizcaino Biosphere Reserve, Baja California Peninsula, Mexico.

Claudio Contreras / Prehistoric rock painting at La Pintada cave, Pronghorn antelope, Bighorn sheep and people depicted, San Francisco Sierra, El Vizcaino Biosphere Reserve, Baja California Peninsula, Mexico.

Claudio Contreras / Prehistoric rock painting of Pronghorn antelope and people, at La Pintada cave. San Francisco Sierra, El Vizcaino Biosphere Reserve, Baja California Peninsula, Mexico.

Claudio Contreras / Prehistoric rock painting of Pronghorn antelope and people. La Pintada cave. San Francisco Sierra, El Vizcaino Biosphere Reserve, Baja California Peninsula, Mexico.

Claudio Contreras / Prehistoric rock painting of Pronghorn antelope and Turkey vulture. La Pintada cave. San Francisco Sierra, El Vizcaino Biosphere Reserve, Baja California Peninsula, Mexico, March

Claudio Contreras / Guide in front of prehistoric rock paintings of Bighron sheep and people. La Pintada cave, San Francisco Sierra, El Vizcaino Biosphere Reserve, Baja California Peninsula, Mexico.

Claudio Contreras / Guide sitting beneath prehistoric rock painting. El Palmarito cave, Santa Martha Sierra, El Vizcaino Biosphere Reserve, Baja California Peninsula, Mexico. 2008.