On a barren hillside just north of Lima, he had found an observatory more than 4,000 years old that had been built by a lost civilisation with astonishing sophistication.

The oldest astronomical observatory in the Americas, it told farmers exactly when to sow their crops. Its discovery has provided startling clues to the way in which early man learnt to cultivate his fields.

“I was staring up at a statue on a ridge above the temple and realised it all aligned with the stars — it was an amazing moment,” the bearded scientist said last week.

“This alignment meant that at dawn at every winter solstice 4,200 years ago, key stars would appear in line with the temple and alert priests that river flooding was due and it was time to start planting crops. It was laid out as a wake-up call to the community.”

Other archeologists now believe that Benfer, 67, has found a temple built in 2200BC, which proves that the ancient Andeans were familiar with the movements of the stars long before the ancient Britons finished Stonehenge, which many believe is linked to the heavens.

Benfer stumbled across the temple while trawling through a green valley floor in search of information about ancient diets. Working with a number of Peruvian colleagues, he unearthed a 30ft-high pyramid that had once been brightly painted red and white. He believes that it served its community, known as the Kotosh people, for 800 years.

The 20-acre site is dominated by two buildings. The northern pyramid, which Benfer has called the Temple of the Fox after a painting of the animal, is built around a priests’ platform.

This points at 114 degrees directly to an 8ft tall carved head on a mountain ridge nearly 200ft away. On December 21 each year, just before the local River Chillon starts flooding, a constellation known to Andeans as the fox swings into the sightline. According to Andean myth, the fox is the creature that taught farmers how to cultivate plants.

To the south, another temple holds a scowling clay head, which Benfer believes represents the earth goddess Pachamama. It aligns with stars that line up when the harvest is due to be gathered.

Larry Adkins, professor of astronomy at Cerritos College in California, said that such alignments were beyond coincidence: “They may not be precise by modern standards, but they are close enough to allow the priests to produce a theatre of predictions.”

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