According to Official Guinness Records,
In the foothills of the Sierra de Atapuerca in northern Spain is a series of prehistoric caves in which a human ancestor - homosapiens antecessor - lived up to 800,000 years ago. Among the hominid skeletal remains are bones and skulls displaying a series of gouges and scars that suggest a tool had been used for skinning, scraping flesh and extracting marrow from bones. The same pattern of markings is mirrored in animal bones found nearby. Further - and later - sites containing evidence of cannibalism among Neanderthals have been found in Croatia and southern France. Outside of Europe, investigations into bones discovered among the remains of the Anasazi peoples of North America have revealed evidence of "pot polish" - the result of stirring body parts in a cooking pot.
For a complete list of Unknown date records, please visit Unknown date Guinness Records in Spain.