According to a recent Newcastle University study, if you want to build a replica of Stonehenge, get some lard – lots of it. By studying neolithic pottery from a site near the ancient stone circle, archaeologists suggest that the traces of pig fat weren't the result of cooking, but were used as a lubricant to help move the gigantic megaliths that now stand on the Wiltshire landscape.

Stonehenge is one of the world's great enigmas, as well as one one of its great ancient wonders. For centuries, people have puzzled, probed, and argued about who built the circles of standing stones, why they were built, and, most puzzling, how they were built.

Legends claim that the Devil or Merlin the wizard brought the stones from Ireland by magic, or that giants carried them from Africa. In modern times, less romantic theories have been put forward, but one great problem is that very few clues remain as to how the stones were moved and erected.

It also doesn't help that Stonehenge wasn't built all in one go, but in stages during the British neolithic period, starting in about 3100 BC and ending around 1600 BC. During this time, the circle was laid out, the bank and ditch dug out, and a series of now long-rotted wooden structures were built – these were later replaced by increasingly elaborate stoneworks.

The greatest of these were the megaliths, which weigh up to 50 tonnes (55 US tons) and were moved to Stonehenge from a source 20 miles (32 km) away in the Marlborough Downs. The smaller bluestones that "only" weigh between two and five tonnes were transported from the Preseli Hills in Wales some 155 miles (250 km) away.

Exactly how these were moved, or how Stonehenge or the many other features on the ritual landscape on Salisbury Plain were constructed is still uncertain. However, a series of experiments over the past 100 years have proven that even the most massive of the stones can be moved with enough manpower, even with the technology of the day.

One very likely technique was that of using sledges and rollers that had been greased in some way. Up until now, this has been largely a matter of conjecture and experimentation, but the Newcastle team found more direct evidence from excavations at Durrington Walls, which is about two miles (3.2 km) northeast of Stonehenge. This was the site of a neolithic village that was occupied for about 500 years from around 2800 to 2100 BC, and was connected with the henge-making activities in the area – including that of a henge of its own.

At Durrington Walls, archaeologists found 300 fragments of Grooved ware, also called Rinyo-Clacton ware. It's an indigenous form of ancient British pottery made by the Neolithic Grooved ware people, dating back to about 3000 to 2000 BC. Typically, it consists of flat-bottomed pots with straight sides and thick walls, often with basket-like patterns, that were hand-formed rather than thrown on a wheel.

Adhering to this pottery were traces of what was once pig fat. According to Senior Lecturer in Landscape Archaeology, Dr. Lisa-Marie Shillito, that in itself isn't unusual – it had long been thought that this was because the pots were used to cook food for the workers building the monuments. However, reconstructions of the pots showed that they were the size of buckets that were too large for cooking or serving food. In addition, the pig bones found in the vicinity didn't match the cooking hypothesis.

"I was interested in the exceptional level of preservation and high quantities of lipids – or fatty residues – we recovered from the pottery," says Shillito. "I wanted to know more about why we see these high quantities of pig fat in pottery, when the animal bones that have been excavated at the site show that many of the pigs were spit-roasted rather than chopped up as you would expect if they were being cooked in the pots."

Shilto's new explanation was that the pots were used to store pig lard, which could then be used as a lubricant for sledges and rollers. However, she emphasizes that there is still work to be done on the mystery.

"There are still many unanswered questions surrounding the construction of Stonehenge," says Shilto. "Until now, there has been a general assumption that the traces of animal fat absorbed by these pieces of pottery were related to the cooking and consumption of food, and this steered initial interpretations in that direction. But there may have been other things going on as well, and these residues could be tantalizing evidence of the greased sled theory.

"Archaeological interpretations of pottery residues can sometimes only give us part of the picture. We need to think about the wider context of what else we know and take a multi-proxy approach to identify other possibilities if we hope to get a better understanding."

The research was published in the journal Antiquity.