Prehistoric Porn

Says Xeni at Boing Boing of the paleolithic porn pics on this Spanish-language website: "Unlike porn sites, archeological sites tend to be free of pop-up ads"—which should at least give you some consolation about their graphically interesting but rather tepid content, since apparently modern tricks like the reverse cowgirl and double anal creampies weren't invented until much later in the development of mankind.

Erotismo Prehistórico/Prehistoric Eroticism (gallery @ arterupestre-c.com, via Boing Boing)

See also: Hardcore Caveman (and Cavewoman) Porn 1, 2, 3 (TGP/preview galleries via Ask Jolene)
"Cave Bang" (hardcore comic @ sex-cartoon-sex.com)