Forget 1759, the most important year in Irish brewing history may have been many thousands of years earlier. A pair of bleary-eyed Galway archaeologists have developed a theory that, in between all the hunting and gathering, one of the most commonly found archaeological features on the Irish landscape was used by Bronze Age man to make ale.

While beer drinking was common throughout the Far East nearly 5,000 years ago and growing evidence exists of the same dissolute behaviour across Bronze Age Europe, a record of brewing in Ireland begins only with the early monastic settlements where monks manufactured beer by the bucketload.

Declan Moore runs the Moore Group archaeological consultancy in Galway city. Along with colleague Billy Quinn, he set out to fill in this gap in the record and to pinpoint when and how the Irish started boozing. They believe the answer may lie hidden in thousands of fulacht fiadhs - horseshoe-shaped mounds with a subtle indentation which are dotted throughout the country.

In an article to be published in Archaeology Ireland next month, the pair detail their "epic quest" across the world in pursuit of early evidence of brewing in northern Europe.

Their quest culminates in Headford, Co Galway, this weekend when they host an event at which only ale brewed using the ingredients and methods they say Ireland's Bronze Age man would have used will be served.

Their beer-soaked journey took them to Barcelona for the Congres Cerveza Prehistorica. They travelled to the Orkneys where they learned more about Neolithic brewing. Hot rock brewing technology brought them to Belgium and Bavaria. Their journey also featured a, perhaps fortunately, unsuccessful attempt to enter Iran to investigate brewing technologies in a country where brewing, new or old, is not now held in high regard.

According to Moore, studies suggest that hunter-gatherers worked between four and six hours a day, leaving them with a lot of time to kill.

"Archaeological evidence demonstrates that intoxicants have been part of human society from earliest times," he says. He points out that as hunter-gatherers had an intimate knowledge of the environment around them and the effects of naturally occurring intoxicants, it would have been remarkable if they had left all the fun to the monks. "Brewing at the monastic settlements was quite advanced, with Irish beer even being shipped over to Belgium at the request of one parched missionary," Moore says. "To get to that stage the manufacturing process must have evolved from somewhere, there has to have been an earlier tradition."

It is widely accepted that the primary function of a fulacht fiadh was to heat water by dropping fire heated stones into a water-filled trough.

It is believed that they were primarily used for cooking but alternative theories suggest they may have been used for bathing, dyeing, tanning and metal-working. Until today no one has suggested that the fulachts were Ireland's earliest breweries. In an attempt to prove their theory, Moore and Quinn set out to recreate the pre-historic brewing process. They used basic equipment including an old, leaky wooden trough caulked with moss and alluvial clay which they sank into a pit in the ground using measurements broadly comparable with excavated examples of fulachts.

Water was added to the trough and then stones heated in a bonfire for two hours brought the water to the optimum brewing temperature of between 60 and 70 degrees. Milled barley was added, boiled and then transferred into specially commissioned Bronze Age reconstructed pots where it was left to ferment. Elder flower and juniper berries were added for flavouring.

The ale, ready for consumption after only three days, was a clear, copper-coloured brew with a sharp, smoky taste. Moore says its smokiness can be explained by the fact that the rocks used to heat it were taken from an open fire.

Moore is keen to stress the end product was not beer as we know it but a quasi-hallucinogenic herbal ale, although for their purposes the hallucinogenic herbs have been left out.

The ale, Moore suggests, would have been consumed on a daily basis as a healthy, uncontaminated, comfort drink. "In the long Bronze Age evenings and nights, family groups likely sat around a blazing fire telling tales, interacting socially and enjoying the warmth, wellbeing and genial companionship that ale enhances."

He counters suggestions that his theory has more holes than a leaky wooden trough and points to the fact that the evidence for the conventional understanding of fulachts is equally limited and is based on experimentation, with little supporting artefactual evidence. "From our own experience excavating fulachts, we believe that the fulacht fiadh was multifunctional, the kitchen sink of the Bronze Age. However, a primary use seems clear - these sites were Bronze Age micro-breweries."