Neolithic engineers used their scientific knowledge to build megalithic monuments.

Neolithic people appear to have understood advanced concepts from sciences such as physics and geology, and used this knowledge to build megalithic monuments in southern Spain.

The dolmen, called Menga Dolmen, was built between 3600 and 3800 BC and is one of the oldest structures of its kind. The covered enclosure is made of 32 large stones, some of which are the largest ever used for such structures. The heaviest weighs over 130 tonnes, more than three times the heaviest stone at Stonehenge in England, which was built more than 1000 years later.

“It must have been very impressive to see these huge (Neolithic) stone structures,” says Leonardo García Sanjuan of the University of Seville in Spain. “It still moves me. It still makes an impression on me.”

García Sanjuan and his colleagues are now conducting a detailed geological and archaeological analysis of the stones to deduce what knowledge Menga’s builders needed to construct the monument in the city of Antequera.

Paradoxically, they found that the rock was a type of relatively brittle sandstone, meaning that it was at high risk of breaking, but the team found that they could compensate for that risk by shaping the rock, locking it into a very stable overall structure.

Neolithic people would have needed some way to make the stones fit together very snugly, Garcia-Sanjuan says. “It’s like Tetris,” he says. “The precision and how tightly each stone is fastened to each other forces you to think they had some concept, even if it was rudimentary, of angles.”

The researchers also discovered that the 130-ton stone, laid horizontally on top to form part of the roof, has a raised surface in the middle and slopes down at the edges, which helps distribute forces in the same way an arch does and strengthens the roof, Garcia-Sanjuan says. “To our knowledge, this is the first time the principle of the arch has been documented in human history.”

The purpose of the mengas is unknown, but they were positioned to create unique light patterns inside them during the summer solstice and the stones are protected from water damage by layers of carefully pounded clay, supporting evidence of their builders’ knowledge of architecture and engineering.

“They knew about geology and the properties of the rocks they were working with,” Garcia San Juan says. “When you put all of this together — engineering, physics, geology, geometry, astronomy — you get what you call science.”

There are other Neolithic structures in France of a similar size to Menga, but less is known about how it was built, Garcia San Juan said. “To date, Menga is unique both in the Iberian peninsula and in Western Europe.”

“The sophistication is astounding,” says Susan Greaney of the University of Exeter, UK. “The architectural understanding of how weight is distributed is something I’ve never seen anywhere before.” But, she adds, this may be a testament to architectural and engineering understanding rather than scientific understanding.