For what it's worth, I reckon the world of Modern Art could learn a lot from the work of Stone Age Man. OK, so I'm not much of a culture-vulture, but during a recent walk, I encountered the most puzzling and thought-provoking piece of art I've ever seen.

It was a bewitching pattern of concentric circles, rings and scattered dots - an abstract composition, yet full of energy and purpose. Surely this must mean something, I asked myself. But what? Most intriguing of all: the artwork in question was not on display in some contemporary London gallery. Instead, it was slap-bang in the middle of a remote forest on the west coast of Scotland.

And far from being the latest offering by one of our celebrated Young British Artists, this was actually the work of our prehistoric ancestors. Although they were carved into the stone some 5,000 years ago, I'd say these cryptic markings remain as captivating and mysterious as anything the art-world has produced ever since.

I'd heard about the rock-carvings at Ormaig while researching the history of Argyll, and decided to set out, with my partner Jennie as photographer, from the village of Kilmartin to find them. After a few miles, we were deep into a thick forestry plantation when we stumbled onto the faint path that leads to the fabulous natural gallery where the rocks are on show (It's at grid ref NM823027, if you want to find them for yourself).

In a clearing, there they were: just as they were left by their original sculptor all those centuries ago. The sheer unimaginable age of these carvings is awe-inspiring; as is the unknowable mystery of their creation. According to archaeologists, these types of cup-and-ring markings are scattered across Scotland, northern England and along the Atlantic coast of Europe. 

Experts reckon they were carved in roughly 3,000BC - around the time when the hunter-gatherer inhabitants of Scotland were starting to abandon their nomadic lifestyle in favour of more settled farming communities. But why? What could have possessed a Neolithic farmer armed only with the most primitive of tools, to spend hours, days, weeks, chipping away at the hard stone?

No-one knows for sure. Maybe they were intended as signposts or markers for a territorial boundary. Or maybe they were designed for some ritual or religious purpose. Perhaps, though, they are simply the early product of mankind's expressive impulse or creative urge: art, in other words.

Personally, I applaud Damien Hirst and Tracey Emin: seen in the right context, their diamond-encrusted skulls and unmade beds are interesting ruminations on society, on humanity, on the state of contemporary culture. But when it comes to enduring appeal and a mystique that reaches out across the ages, surely they can't even hope to compete with the anonymous Stone Age artists of Ormaig? 

Only time will tell...