HUMAN skulls were systematically manufactured as recently as the Bronze Age to make pots and drinking cups, new research shows.

Meticulous extraction of the scalp and flesh was used to clean the skulls and turn them into bowls, personalised decorations and war trophies as recently as 4,000 years ago.

While the use of these container-shaped bones is still unknown, new evidence suggests skulls were prepared for ritual practices for almost 15,000 years and were, in most cases, linked to human cannibalism during recent Prehistory.

Scientists made the discovery from marks on fossils, studied like bone maps, from Gough's Cave in Cheddar, believed to have been occupied around 9,000 years ago - and other European sites.

Skull cups were identified from Upper Paleolithic, about 20,000 years ago, to the Bronze age, about 4,000 years ago.

Meticulous breaking of these skulls suggests that they are not only related to the need to extract the brain for nutritional purposes, but that they were specifically and intentionally broken to make containers or vessels.

The study was led by researchers at London's Natural History Museum, the Catalan Institute of Human Paleoecology and Social Evolution and the Rovira and Virgili University of Tarragona (URV) in Spain.

Lead study author Francesc Marginedas, a masters student at URV, said: "The ritual use of human skulls has been documented in several archaeological sites of different chronologies and geographical areas.

"This practice could be related to decapitations for obtaining war trophies, to the production of masks, as decorative elements,even with engravings, or to what is known as skull cups.

"In fact, some ancient societies considered that human skulls possessed powers or life force, justifying sometimes its collection as evidences of superiority and authority during violent confrontations."

Systematic fabrication of the skulls began with the removal of the scalp and continued with the removal of muscle tissue.

The human skulls were then broken to preserve the thickest part of the cranial vault and links have been made to human cannibalism.

Mr Marginedas said: "The use of these container-shaped bones is still unknown.

"The repetition of this observed pattern provides new evidences of skulls' preparation for ritual practices, and are associated in most cases to human cannibalism during recent Prehistory."

Scientists recognised possible ceremonial practices by examining signals preserved on the bones.

The most common modifications related to the ritual treatment of skulls were cut marks from scalp removal, produced by stone tools or metal knives.

Mr Marginedas said: "This practice is archeologically well documented among American Paleo-Indians, for example, who show circular arrangements around the head as signs of this type of practices."

In their research, the team developed a statistical analysis to assess whether the cut marks on skull fragments responded to a systematic processing.

Sites included Gough's Cave in Cheddar Somerset, the Spanish caves of Gran Dolina and la Cueva de El Mirador, Fontbrégoua, France and Herxheim, Germany.

Results revealed there is a specific pattern showing treating skull practices that were perpetrated during almost 15,000 years.

Researchers considered the bone as a map on which surface modifications are distributed and where it can be assessed whether if it is possible to identify specific patterns on the elaboration of cup skulls by comparing evidence among the different sites.

Mr Marginedas said: "Specific modifications related to this human behaviour have been identified and the relevance of the cut marks location in specific areas of the skulls has been statistically described.

"Signals made by using stone tools, when meticulously and repeatedly extracting the scalp and meat.

"There are actions that indicate an intense cleaning of skulls in the specific cases of Gough's Cave, Fontbrégoua, Herxheim and El Mirador.

"However, this model has not been observed on the remains of Homo antecessor from level TD6.2."

The findings were published in the prestigious Journal of Archaeological Science.