Castlepook’s MIS 3 Fauna – Emerald Archives

Dateline

The label 31,910 BCE has a deceptive exactness. No people in Ireland then used a calendar, and archaeology cannot isolate an event, ruler or journey to that single modern year. In conventional conversion it lies about 33,859 years before AD 1950, within Marine Isotope Stage 3 (MIS 3), broadly c. 57,000–29,000 calibrated years before present. The responsible subject is therefore not a fictional ‘year in Ireland’, but an interval around it: a late-Pleistocene world known from cave deposits, fossil bones, glacial landforms and changing sea levels. These forms of evidence are precious, but they are not a diary. They describe environments and animal movements over long spans, often with substantial uncertainty.

A Landscape in Transition

Ireland stood within the last Ice Age, but it should not be imagined as a simple, permanently frozen island under one unchanging sheet of ice. MIS 3 was climatically unstable, and the growth, extent and behaviour of the British–Irish Ice Sheet varied regionally and through time. Research on southern Ireland indicates that the main expansion of the last Irish ice sheet began from initially ice-free conditions at about 34,000 years ago and reached the south coast only after about 24,000 years ago. Around this notional date, then, parts of Ireland may have remained available to cold-adapted animals even as glacial conditions intensified elsewhere. That is an interpretation from regional geological evidence, not a precise map of conditions on any one day or in every valley.

Sea level was lower globally than it is now, because more water was held in ice sheets. Yet lower sea level does not automatically mean that a dry and dependable route joined Ireland to Britain or continental Europe. Relative sea level around Ireland was altered by the weight of ice depressing the land, while ice, water and exposed shelf changed together. Reconstructions of Irish insularity are particularly cautious even for much later periods. For c. 33.9 thousand calibrated years ago, it is safer to say that the geography of coasts and crossings differed greatly from the modern map than to claim a specific land bridge or migration corridor.

The Cave Near Doneraile

The chief Irish evidence relevant to this period comes from Castlepook Cave, also called Mammoth Cave or Doneraile Cave, in the limestone country north of Doneraile, County Cork. It is not a settlement excavated in modern conditions. Much of its famous bone collection was recovered during antiquarian investigations in the early twentieth century, when recording methods were far less exact than today. Subsequent work has shown that water disturbance, carnivore activity and earlier digging complicated the deposits. Cave bones can be washed, dragged, re-deposited or accumulated by scavengers; they need not represent animals killed, eaten or even encountered by people at the cave.

Nevertheless, Castlepook is exceptionally important. It is Ireland’s richest known archive of vertebrate life leading up to the Last Glacial Maximum. Its Pleistocene fauna includes woolly mammoth, giant deer, reindeer, brown bear and spotted hyaena; later parts of the record also include such cold-climate animals as Arctic fox, wolf and lemmings. These finds establish that Ireland was, at different moments in the late Pleistocene, reached by a much broader mammal community than survives today. They do not establish that every listed species shared the same hillside, season or century. The cave is a time-averaged archive, not a photograph of 31,910 BCE.

Radiocarbon work has made that distinction more important, not less. The Irish Quaternary Fauna Project originally demonstrated a substantial pre-Last Glacial Maximum mammal record, while later re-dating of material from Castlepook, Foley and Shandon caves found that some earlier results were thousands of radiocarbon years too young. The revised study suggests that giant deer and spotted hyaena may have disappeared locally before about 40,000 calibrated years ago. Thus a mammoth, hyaena or giant-deer bone in the Castlepook collection is compelling evidence for Ice Age Ireland, but cannot simply be assigned to the modern calendar label 31,910 BCE. Dates must be calibrated, their statistical ranges respected, and the archaeological context considered separately.

Animals, Not an Irish ‘Nation’

The fauna nevertheless permits a careful environmental reconstruction. Reindeer, mammoth, lemmings and Arctic fox point to episodes of markedly cold conditions and largely open habitats rather than the dense temperate woodland familiar from much later Ireland. Large herbivores would have needed extensive grazing or browsing grounds, while predators and scavengers followed the opportunities such animals created. Spotted hyaena is especially significant. Castlepook is Ireland’s only known site for the species, and hyaenas commonly transport carcass parts and bones into dens. Their presence is a warning against treating every fractured or marked bone as evidence of hunting by humans.

For everyday life, economy and settlement, however, the evidence is almost wholly silent. There are no securely dated houses, hearths, stone-tool floors, burials, storage pits, boats or camps from Ireland around this time. There is no basis for naming a community, estimating a population, or describing a regular seasonal round. If people briefly reached Ireland during favourable phases of MIS 3, they would probably have been highly mobile hunter-gatherers, as were Upper Palaeolithic groups elsewhere in north-west Europe. But that is a comparative possibility, not a demonstrated Irish social system. It cannot be used to populate the island with permanent bands, tribal territories or a continuous ancestry.

A Possible Human Trace

The reason this period has become especially interesting is a reported reindeer femur fragment from the Castlepook collection. It has been described as bearing marks consistent with butchery by a sharp stone implement and as dating to roughly 33,000 years ago. If the age of the bone and the interpretation of the marks are both upheld, it may indicate that a person processed reindeer in Ireland during the Upper Palaeolithic—an immensely earlier human trace than was once expected. In practical terms, such an action might have involved removing meat, hide or sinew from a carcass. Yet one modified bone would record an episode, not necessarily a hunt at the cave, much less a permanent occupation.

This claim requires restraint. The relevant specimen derives from an old collection rather than a newly excavated, sealed living surface, and no associated contemporary tool assemblage, hearth, dwelling or human remains has been published. County Cork’s archaeological survey accordingly stresses the historic absence of clear human traces from the main Castlepook assemblage, while the National Museum of Ireland continues to state that clear evidence for humankind in Ireland during the Palaeolithic has not yet emerged. Those positions are not a reason to ignore the reindeer bone; they explain why it should be treated as a potentially transformative but unconfirmed indication rather than settled fact.

There is firmer evidence for a much later Upper Palaeolithic human presence at Alice and Gwendoline Cave in County Clare. A butchered brown-bear patella there has two independent radiocarbon determinations in the range c. 12,810–12,590 calibrated years before present. This does not prove an occupation 20,000 years earlier at Castlepook. Instead, it shows the value of direct dating, microscopic study and transparent contextual analysis in a landscape where caves preserve tantalising fragments but rarely complete stories.

No Politics, No Diplomacy

There can be no responsible account of Irish political affairs, war, diplomacy, religion, formal learning or trade in 31,910 BCE. No written language, named institution, political boundary, shrine or exchange network is known from Ireland at this date. Nor can cave animals be made to stand for a people’s beliefs. Upper Palaeolithic art, ornaments and burial practices are known elsewhere in Europe, but importing them into Cork would confuse analogy with evidence. The archaeological record permits no statement about language, kinship, leadership, ritual or collective identity on the island.

Conflict is equally unknowable. Predation, scavenging and competition for shelter were ecological realities, but they are not evidence of human warfare. The principal drama securely visible in Ireland is environmental: species moved through, occupied or disappeared from a shifting north Atlantic landscape; ice accumulated; sea and land relations changed; caves preserved a partial bone record. The human story, if there was one, remains at the threshold of detection.

What This Date Means

The importance of 31,910 BCE lies not in an anniversary but in a question. Castlepook shows that late-Pleistocene Ireland supported, or was visited by, animals including mammoth, reindeer, giant deer, bear and hyaena across a long and changing interval. It also holds a reported clue that humans may have entered that world far earlier than the formerly accepted post-glacial chronology. New excavations at the cave have the potential to test that proposition further. Until securely associated artefacts or undisturbed occupation evidence appears, the best conclusion is modest: around this point in MIS 3, Ireland was an unstable Ice Age landscape with a rich but chronologically complex fauna, and perhaps the faintest possible trace of human activity.

Primary Sources

Tags: Castlepook Cave, Castlepook’s MIS 3 Fauna, County Cork, Ireland Year by Year, Last Glacial Maximum, May