Science: Beer? It's simply not British]: The ancient Sumerians were probably the first brewers in the world, reports John Nicholson

THERE is nothing quite as British as drinking beer. From Inspector Morse, taking a well-earned sup to aid his thinking, to characters in The Archers enjoying pints of Shires in the Bull, there is a homely British feel to beer. And it must be beer. Not the light Continental stuff known as lager, a substance as alien to the British way of life as the louts who made it briefly notorious in the late Eighties.

Yet beer is not native to this country. It is not even native to Europe, but has its origins in the Middle East. Historians have known for a long time that the ability to turn barley into a fermented drink was a skill possessed by ancient civilisations around the Mediterranean. Agricultural experts have also found strong evidence that cultivated barley originated in Egypt. If both of these views are correct, it seems likely that fermentation know-how travelled with the cultivation of barley as it gradually spread northwards to Britain.

Science has now confirmed part of this picture: chemical analysis has identified a 6,000-year-old brewery at an archaeological site in what is now modern Iran. The evidence, which was published recently in the scientific journal Nature, suggests that fermentation of barley was first practised in Sumer - southern Babylonia - between 4000 and 3000 BC. The Sumerian civilisation occupied the flood plain between the lower Tigris and Euphrates rivers, land that is today mainly shared by Syria and Iraq. One of the oldest literate civilisations, the Sumerians had a sophisticated system of agriculture, in which irrigation was used to grow cereal crops, including barley.

Towards the end of last year, archaeologists found a jar from the late fourth millennium BC at Goden Tepe (just inside the border of Iran). It has grooves containing traces of calcium oxalate, the main component of 'beerstone', a substance that settles on the surfaces of storage tanks of fermented drinks brewed from barley. The only other foodstuffs to contain an appreciable amount of oxalates are spinach and rhubarb, neither of which plays a key part in the human diet.

The archaeologists working on this ancient artefact, Rudolph Michel and Patrick McGovern of the University of Pennsylvania, and Virginia Badler of the University of Toronto, have concluded that it was used as a vessel for a fermented barley drink. If this is indeed the case, then they have stumbled across the earliest record of such brewing in history.

The original drink was not beer itself, but ale. Ale is made by the same fermentation process as beer, but does not include hops. Without hops, the drink is less bitter, pale in colour and does not have a head.

Fermentation is a complicated process, and no one knows how long it took to develop fully, nor how much the ancient brewers knew about the process. The first step is to convert barley's insoluble starch into a soluble form, which today is done by making malt from the barley. Making malt involves allowing the barley just to germinate, then stopping any further growth by gentle heating. Heating in this way also imparts the characteristic biscuity flavour.

Once the starch has been converted to a soluble form, it is extracted and degraded by warm water to yield its sugars. These form a solution known as the wort, and fermentation by yeasts converts it to alcohol and carbon dioxide. This is the most important part of the brewing process.

Malting, however, is not the only way of making the starches in barley soluble. Another method, still current in Egypt and probably the one used by the Sumerians, is akin to bread- making. In this process, sour-dough containing yeast is added to newly germinated moist barley, and the mixture is made into loaves, then baked gently to just form a crust and leave the inside uncooked. When the time comes to make ale, this loaf is broken up and added to water, and the whole lot ferments happily.

Little is known for certain about the discovery of fermentation of barley. The process is less obvious than making wine by the fermentation of grapes, because grapes on the vine naturally acquire a 'bloom' of yeast. This means that just picking and crushing the grapes brings the yeast and the sugar into contact.

Fermentation of the grape sugars into alcohol follows on from this without difficulty. Yeasts are found in all sorts of habitats throughout the world, however, and barley, like grapes, has its own set of them. Barley leaves, for instance, are known to harbour wild yeasts, and so are kept well out of the way in modern brewing.

In ancient Sumer, these wild yeasts were all they had for fermentation. As a result, the ale must have at first been pretty indifferent both in taste and general quality. Later, though, the Sumerian brewers must have realised that a good yeast could be kept alive and used to ferment several batches of ale. With this knowledge, the quality would have soon improved.

We know that Britain had the resources to make ale as long ago as the first century BC. Julius Caesar, for example, found cereals under cultivation when he came, saw and conquered Britain in the summer of 55 BC. What proportion of these cereals was converted into ale is not clear. At that time ale had two rivals, cider and mead, which were drunk extensively in some parts of the country. The word beer comes from the old English 'beor', which was used in Saxon times for an inferior sort of mead. The word disappeared from the English language for 500 years, only to reappear as the name for the bitter liquor flavoured with hops.

The use of hops was the final big improvement in beer-making, and even this did not originate in Britain. Again, how it began is a mystery, but it was widespread on the Continent, particularly in the Low Countries, some 500 years ago. The first recorded cultivation of hops in Britain was in 1524, when Flemish immigrants began growing the crop in Kent. The hop plant will only flourish given the right combination of soil and climate, and is difficult to grow successfully as far north as England. Kent was soon found to be one of the few parts of the country with the necessary conditions, and hop-growing remains a commercial activity.

So there we are. Beer is not so British, after all. Modern products, particularly our popular bitters, seem to be a highly refined version of an original Sumerian idea. If anything, it is through development, not invention, that we have made our gift to the world. Something to ponder on the next time you're in the pub. As for me, all this talk about beer has made me thirsty. Time for a quick half, I think - all in the interests of historical research, of course.

Dr John Nicholson is a research chemist at the Laboratory of the Government Chemist, Teddington, and a visiting lecturer in chemistry at King's College London.

(Photographs omitted)