THE possibility that human intelligence originated from interbreeding with alien visitors who created monuments such as Silbury Hill is explored in Devizes writer John Cowie's first book.

Mr Cowie, who in his career has been a senior executive with several leading computer companies, creates plenty of food for thought in his £9.99 paperback Silbury Dawning, which has been acclaimed by researchers on both sides of the Atlantic.

He admits that he opens himself to criticism as being a crank with his quest to establish why the human race is more intelligent than other creatures on earth and to try to discover the real purpose of huge man-made monuments like Silbury, Avebury and Stonehenge.

He ponders the suggestion that they were, perhaps, beacons, to guide alien craft to their landing sites.

Mr Cowie, 54, of Waterbrook Mews, Devizes, also links the phenomenon of crop circles with the alien theory. He thinks there is a chance the monument has attracted the landings of space craft, which many believe are responsible for the crop circles.

"It occurred to me that if this were the true explanation for the construction of Silbury Hill then it might have been used as a beacon for thousands of years. Perhaps it was built for the purpose of attracting craft to a safe landing site," he said.

Mr Cowie said the purpose of constructions like Silbury, Avebury stone circles and Stonehenge remained unclear but they would have been visible from the sky.

In his book he says: "The Alien Visitor left behind clues to confirm its visit to our planet. Several can be found in the physical evidence that exists on earth and I believe other clues can be found in the functions of our developed brain."

He asks: "Why do human beings possess intelligence so superior to that of our closest relatives, especially when it is known that they share 98.4 per cent of their genetic make-up with the African chimpanzee?"

Mr Cowie adds: "I find it difficult to accept that our intelligence is purely the result of the slow process of evolution. After all, it took around two million years for our earliest ancestors to appear.

"But in just a hundred years we have seen the average IQ, height and longevity of life in our race increase demonstrably. And in the past 30 years I have witnessed phenomenal developments in the computer and communication industries in which I have worked all my life.

"It seems to me that at some point along our evolutionary path we may have had some help, which enabled us to make out outstanding achievements."

Mr Cowie concludes: "My theory is that the rapid evolution of our intelligence is due to the arrival on earth of a highly intelligent extra-terrestrial being, or race of beings which I call the Alien Visitor which bred with and educated our homo sapiens ancestors.

"I believe the arrival of the Alien Visitor advanced our evolution by millions of years. Without this, we could still be slowly travelling along the evolutionary timeline, developing our intelligence as we struggle to survive."

He said that without the alien intervention our skills today would be not much more than those of our ancestors.

Mr Cowie told the Gazette that for years he had been fascinated by Silbury Hill and wondered why it was originally built.

"Alongside this I've become more and more amazed at the huge leaps in technology which I have witnessed within the last 25 years. I started to think about our intelligence a lot and wonder where it came from.

"Eventually I started to think that things like Silbury Hill, Avebury and Stonehenge might be connected with the root of our knowledge."

Mr Cowie has set up a website www.silburydawning.com around the book.