HERE'S a brief but instructive experiment concerning Scottish history. Start up your internet browser of choice and type in "Highland Clearances". You'll get somewhere around 21,900 results, the first of which is a site dedicated to archiving primary sources and publishing first-hand accounts of one of Scottish history's most tumultuous periods. Then, type in "Lowland Clearances" and you'll be rewarded with fewer than 1000 results, most of the first page of which will be links to sites selling one book: Peter Aitchison and Andrew Cassell's The Lowland Clearances: Scotland's Silent Revolution, 1760-1830, until now the only work published on the matter, itself based on a three-part BBC Scotland documentary.

"Now why should that be?" asks Professor Tom Devine, director of the Centre for Irish and Scottish Studies at Aberdeen University and author of the bestseller The Scottish Nation, 1700-2000, who was also heavily involved in the BBC documentary series. The Lowland Clearances, he explains, caused many more evictions than the Highland ones. During the 1990s, as he was working on The Scottish Nation, a chapter of which is devoted to the Lowland Clearances, Devine researched the records of four counties: Angus, Ayr, Fife and Lanark, examining both legal papers and parish records.

In these four counties, anywhere between one-third and half the population was displaced, all in a short few decades in the latter 18th and early 19th centuries. The minister for Kilmany, in Fife, says Devine, wrote of "the annihilation of the cottagers".

In Angus, one parish report contained the phrase, "many of the cottagers have been exterminated".

Devine asks: "Why the historical amnesia, not just among the public, but among professional scholars?" It's a question Devine intends to answer at Word 05.

There are a few reasons. The first, he says, is that "when the great removals of people took place in the 18th century, landlordism and social hierarchy were barely questioned; it was almost as if it was accepted that the elite had the right to do this."

Feudalism - that great, lurching relic, the hangover of pre-modern times - actually helped usher in the modern world; it sped the progress of the agricultural and industrial revolutions. "The speed of capitalist change, of economic modernisation was faster [in Scotland] than in England. It's almost as if the old world was being integrated with the new." And landlords, with their heredity-derived powers, "were in a sense able to use this ancient historical muscle, if you want to call it that, with very little question."

One of the other main reasons why we know so little about the Lowland Clearances, in Devine's view, is that they were successful. Over some 50 years, cottars - Lowland crofters, who comprised a good third of the population in the areas Devine studied - were gradually evicted by stealth.

There was no Lowland Patrick Sellars violently removing families from their crofts. The Lowland Clearances were the product of the legal system, and the lawyer sons of local landowners, "trained at Scottish universities, and factors for the big estates". They had no qualms, no problem, Devine says, "with using legal muscle". The most common, and the easiest, way for a landlord to clear his property was through increasing rent, "so that people would have great difficulty in paying it, and would surrender the land voluntarily".

In addition, there were what Devine calls "improving leases". The landlord, through his factor, would have a legal deed - a tack - which would contain a series of clauses:

"Farmers would have to plant in a certain way, or grow certain crops, and if they didn't, they'd be given a stay of execution, for maybe a year, then that was it. Again, it was all about the hierarchical society.

Landowners could get away with, if not murder, then a lot more than in the later 19th century."

There was never a situation - as there was in the Highlands in the 1840s and 1850s - where famine was possible, "where you have a society so poor and impoverished and vulnerable that a crop failure leads to mass destitution. My feeling is that if a lot of the things landowners had actually done in the Highlands had succeeded, the scar of the Clearances would not be nearly so deep."

Come the middle of the 19th century, it was famine or emigration. However, in the Lowlands 80 years before: "People could find work in the new agriculture, albeit at a slightly lower social status, or they could move to the new villages which were being established, or of course they could move into the towns, which were growing more rapidly than any other part of Europe at that point in time."

Another key factor in the differences between the two experiences was that, for Lowland tenants and their landowners, by the mid-18th century the land transaction was a purely economic one, lacking, as Devine says, the Gaelic idea of duathchas, an almost untranslatable concept which revolves around the obligations of the landowner to his tenants, and the tenants' own duties of providing military service, through the clan system, in return for land.

"There was nothing like that in the Lowlands, " admits Devine. "There was maybe contingent paternalism but there was nothing like the emotional, psychological and historical linkage."

The success, as it were, of the Lowland Clearances has even removed the physical traces of the cottars. Unlike in the Highlands, in the Lowlands, with the odd exception in the Southern Uplands and in the Borders, "there is no evidence of the old world, because what tended to happen was that, in the building up of the new and improved farming, the stone from the old cottages was used for the building of new walls and cottages of new farmworkers".

The Enlightenment, too - that great bastion of Scottish rationality, many of whose proponents were strong-minded individualists with a hatred for Scotland's "obscurantist past" - should shoulder its share of the blame for the Lowland Clearances. Very few ministers questioned what was happening in their parishes; if the process did have social costs, says Devine, they were seen as being for the greater good.

"Even people at the time seemed to regard this as a necessary process, and in fact, the Enlightenment helped give intellectual legitimacy to the actual process of economic modernisation."

Between 1760 and 1830, the old Lowland world of the "ferm touns" disappeared. In the words of English radical William Cobbett, visiting the Lothians in the 1820s:

"Everything is abundant here but people, who have been studiously swept from the land." And, until now, from history.

Tom Devine is at the King's College Centre on Sunday May 15 at 2.45pm