Prehistoric Ireland
The prehistory of Ireland has been pieced together from archaeological evidence, which has grown at an increasing rate over recent decades. It begins with the first evidence of permanent human residence in Ireland around 10,500 BC and finishes with the start of the historical record around 400 AD. Both the beginning and end dates of the period are later than for much of Europe and all of the Near East. The prehistoric period covers the Palaeolithic, Mesolithic, Neolithic, Bronze Age and Iron Age societies of Ireland. For much of Europe, the historical record begins when the Romans invaded; as Ireland was not invaded by the Romans its historical record starts later, with the coming of Christianity.
File:UlsterMuseumPrehistoryBrGold.JPG|thumb|Bronze Age gold dress-fasteners and torc, amber necklace, Ulster Museum
The two periods that have left the most spectacular groups of remains are the Neolithic, with its megalithic tombs, and the Bronze Age, which left among other things, gold jewellery from a time when Ireland was a major centre of gold mining.
Ireland has many areas of bogland, and a great number of archaeological finds have been recovered from these. The anaerobic conditions sometimes preserve organic materials exceptionally well, as with a number of bog bodies, a Mesolithic wicker fish-trap, and a Bronze Age textile with delicate tassels of horse hair.
Glaciation and the Palaeolithic
During the Last Glacial Maximum, ice sheets more than thick scoured the landscape of Ireland. By 24,000 years ago they extended beyond the southern coast of Ireland, but by 16,000 years ago the glaciers had retreated so that only an ice bridge remained between Ireland and Scotland. By 14,000 years ago Ireland was completely isolated from Britain; this glacial period is recognized as having ended about 11,700 years ago, without glaciers being present, but leaving Ireland as an arctic tundra landscape. This period is referred to as the Midlandian glaciation.During the period between 17,500 and 12,000 years ago, a warmer period referred to as the Bølling-Allerød allowed for the rehabitation of northern areas of Europe by roaming hunter-gatherers. Genetic evidence suggests this reoccupation began in southwestern Europe, and faunal remains suggest the existence of a refugium in Iberia that extended into southern France. Species originally attracted to the north during the pre-boreal period included reindeer and aurochs. Some sites as far north as Sweden inhabited earlier than 10,000 years ago suggest that humans might have used glacial termini as places from which to hunt migratory game.
These factors and ecological changes brought humans to the edge of the northernmost ice-free zones of continental Europe by the onset of the Holocene and this included regions close to Ireland. However, during the early part of the Holocene, Ireland itself had a climate that was inhospitable to most European animals and plants. Human occupation was unlikely, although fishing was possible.
Ireland was not joined to Great Britain by a land bridge, meaning that snakes and other temperate terrestrial flora or fauna could not have crossed into Ireland. Unlike Great Britain, which was connected to continental Europe by a continuous land bridge, called Doggerland, until 7050 BC.
The earliest known modern humans in Ireland date back to the late Palaeolithic Age. This date was pushed back some 2,500 years by radiocarbon dating performed in 2016 on a bear bone excavated in 1903 in the "Alice and Gwendoline Cave", County Clare. The bone has cut marks showing it was butchered when fresh and gave a date of around 10,500 BC, showing humans were in Ireland at that time, soon after the ice retreated. In contrast, a flint worked by a human found in 1968 at Mell, Drogheda, is much older, probably well pre-dating 70,000 BC, and this is normally regarded as having been carried to Ireland on an ice sheet, probably from what is now the bottom of the Irish Sea. In 2021, a reindeer bone fragment discovered in Castlepook Cave near Doneraile, County Cork in 1972, was dated to 33,000 years ago, establishing human activity in Ireland more than 20,000 years earlier than previously thought.
Mesolithic (8000–4000 BC)
The last ice age fully came to an end in Ireland about 8000 BC. Until the single 2016 Palaeolithic dating described above, the earliest evidence of human occupation after the retreat of the ice was dated to the Mesolithic, around 7000 BC. By the time the first settlers arrived to Ireland by boat, presumably from Britain, the ice bridge to Great Britain would have melted. The earliest inhabitants of the island were seafarers who depended for much of their livelihood upon the sea, and later inland settlements or camps were usually close to water. Although archaeologists believe Mesolithic people heavily relied on riverine and coastal environments, ancient DNA indicates they had probably ceased contact with Mesolithic societies on the island of Britain and further afield.Evidence for Mesolithic hunter-gatherers has been found throughout the island: a number of the key early Mesolithic excavations are the settlement site at Mount Sandel in Coleraine, County Londonderry; the cremations at Hermitage House, County Limerick on the bank of the River Shannon; and the campsite at Lough Boora in County Offaly. As well as these, early Mesolithic lithic scatters have been noted around the island, from the north in County Donegal to the south in County Cork. The population has been tentatively estimated at around 8,000.
File:UlsterMuseumPrehistoryMe .JPG|thumb|The Moss-side hoard of Mesolithic Bann flake tools and blades, Ulster Museum
The hunter-gatherers of the Mesolithic era lived on a varied diet of seafood, birds, wild boar and hazelnuts. There is no evidence for deer in the Irish Mesolithic and it is likely that the first red deer were introduced in the early stages of the Neolithic. The human population hunted with spears, arrows and harpoons tipped with small stone blades called microliths, while supplementing their diet with gathered nuts, fruit and berries. They lived in seasonal shelters, which they constructed by stretching animal skins or thatch over wooden frames. They had outdoor hearths for cooking their food. During the Mesolithic the population of Ireland was probably never more than a few thousand. Surviving artefacts include small microlith blades and points, and later larger stone tools and weapons, in particular the versatile Bann flake.
Neolithic (4000–2500 BC)
Many areas of Europe entered the Neolithic with a 'package' of cereal cultivars, pastoral animals, pottery, weaving, housing and burial cultures, which arrived simultaneously, a process that began in central Europe as LBK about 6000 BC. Within several hundred years this culture was present in northern France. An alternative Neolithic culture, La Hoguette culture, that arrived in France's northwestern region appears to be a derivative of the Ibero Italian-Eastern Adriatic Impressed Cardial Ware culture. The La Hoguette culture, like the western Cardial culture, raised sheep and goats more intensely. By 5100 BC there is evidence of dairy practices in southern England, and modern English cattle appear to be derived from "T1 Taurids" that were domesticated in the Aegean region shortly after the onset of the Holocene. These animals were probably derived from cattle from the Linear Pottery culture. Around 4300 BC cattle arrived in northern Ireland during the late Mesolithic period. The red deer was introduced from Britain about this time.From around 4500 BC a Neolithic package that included cereal cultivars, housing culture and stone monuments arrived in Ireland. Sheep, goats, cattle and cereals were imported from southwestern continental Europe, after which the population rose significantly. The earliest clear proof of farmers in Ireland or Great Britain is from Ferriter's Cove on the Dingle Peninsula, where a flint knife, cattle bones and a sheep's tooth were found and dated to. At the Céide Fields in County Mayo, an extensive Neolithic field system has been preserved beneath a blanket of peat. Consisting of small fields separated from one another by dry-stone walls, the Céide Fields were farmed for several centuries between 3500 and 3000 BC. Wheat and barley were the principal crops cultivated. Pottery made its appearance around the same time as agriculture. Ware similar to that found in northern Great Britain has been excavated in Ulster and in County Limerick. Typical of this ware are wide-mouthed, round-bottomed bowls.
This follows a pattern similar to western Europe or gradual onset of Neolithic, such as seen in La Hoguette Culture of France and Iberia's Impressed Cardial Ware Culture. Cereal culture advance markedly slows north of France; certain cereal strains such as wheat were difficult to grow in cold climates—however, barley and rye were suitable replacements. It can be speculated that the DQ2.5 aspect of the AH8.1 haplotype may have been involved in the slowing of cereal culture into Ireland, Scotland and Scandinavia since this haplotype confers susceptibility to a Triticeae protein induced disease as well as Type I diabetes and other autoimmune diseases that may have arisen as an indirect result of Neolithisation.
Monuments
The most striking characteristic of the Neolithic in Ireland was the sudden appearance and dramatic proliferation of megalithic monuments. The largest of these tombs were clearly places of religious and ceremonial importance to the Neolithic population, and were probably communal graves used over a long period. In most of the tombs that have been excavated, human remains—usually, but not always, cremated—have been found. Grave goods—pottery, arrowheads, beads, pendants, axes, etc.—have also been uncovered. These megalithic tombs, more than 1,200 of which are now known, can be divided for the most part into four broad groups, all of which would originally have been covered with earth, that in many cases has been eroded away to leave the impressive stone frameworks:; Types of Irish megalithic tombs
- Court cairns – These are characterised by the presence of an entrance courtyard. They are found almost exclusively in the north of the island and are thought to include the oldest specimens. North Mayo has many examples of this type of megalith – Faulagh, Kilcommon, Erris.
- Passage tombs – These constitute the smallest group in terms of numbers, but they are the most impressive in terms of size and importance. They are also found in much of Europe, and in Ireland are distributed mainly through the north and east, the biggest and most impressive of them being found in the four great Neolithic "cemeteries" of the Boyne, Loughcrew, Carrowkeel and Carrowmore. The most famous of them is Newgrange, one of the oldest astronomically aligned monuments in the world. It was built around 3200 BC. At the winter solstice the first rays of the rising sun still shine through a light-box above the entrance to the tomb and illuminate the burial chamber at the centre of the monument. Another of the Boyne megaliths, Knowth, has been claimed to contain the world's earliest map of the Moon carved into stone.
- Portal tombs – These tombs include the well known dolmens. They consist of three or more upright stones supporting a large flat horizontal capstone. They were originally covered with earth to form a tumulus, but often their covering has now eroded to leave the impressive main stone structure. Most of them are to be found in two main concentrations, one in the southeast of the island and one in the north. The Knockeen and Gaulstown Dolmens in County Waterford are exceptional examples.
- Wedge tombs – The largest and most widespread of the four groups, the wedge tombs are particularly common in the west and southwest. County Clare is exceptionally rich in them. They are the latest of the four types and belong to the end of the Neolithic. They are so called from their wedge-shaped burial chambers.