Ireland’s Newage Tomb is 5,000 years old. The huge and sophisticated tomb is believed to have been built for a powerful elite. Dna from a man buried here suggests he is a descendant of incest. Is this a strategy to maintain aristocratic ancestry? An exciting result in a DNA study of Irish Stone Age residents has had profound implications for our understanding of the migration of prehistoric humans and the structure of ancient societies. Cassidy et al. reported on their amazing findings in the project in Nature.
The authors focused on the period around 4000 B.C., when farming was a new way of life in the Neolithic period, replacing the more mobile fishing and hunting life that earlier occurred in the Middle Stone Age, which was dominated by the search for wild food. Newage Passage Tomb, Ireland. Cassidy et al. analyzed the DNA of a man buried in the 5,000-year-old tomb, and their report showed signs of incest. Source: Ken Williams/ShadowsandStone.com.
Cassidy et al. studied the social structure of these farming masses that fell over the next 1500 years, focusing on people buried in passage tombs, single chambers accessible by the passage, covered with mounds above them. Ireland’s most famous passageway tomb is the huge Newgrange tomb (Figure 1), which is part of a UNESCO World Heritage Site. One of three large tombs, one of which is a giant round mound, is a large tomb in the Brein Valley Tomb complex in County Meath, north of Dublin in eastern Ireland.
The Newgrich tomb was built around 3200-3000 BC. The architectural design uses sophisticated engineering techniques to ensure that the tomb, located at the end of the narrow slate passageway, is illuminated for several minutes at sunrise around the winter solstice each year. In the old days, the tomb was about 500 years older than Stonehenge’s huge trilithon structure. The three-stone structure is also oriented towards the sunrise and sunset of the winter and summer solstice. Recording the annual winter solstice is crucial for early farmers, who need to know when the day starts to grow longer. The construction of Newage’s tomb was a great idea, and archaeologists believe it was built for a powerful elite. People are likely to come from all over the world to attend important winter solstice celebrations. Perhaps the powerful man had declared to the public his divine power by being able to “control” the movement of the sun.
Cassidy and others, after analyzing ancient DNA taken from human remains, unexpectedly discovered a rare case of incest. A man buried at Newage’s tomb about 5,000 years ago is a descendant of first-degree incest: his parents are either siblings, sons and children or father-daughter. The results led researchers to speculate that the powerful, who had been sleeping in this magnificent tomb, had used incest as a way to maintain the royal lineage. This approach broke the almost common concital taboo of human society, but it reappeared long after the elite ruling classes of ancient Egypt, the Inca Empire and ancient Hawaii.
However, this is only one of many findings in this groundbreaking report. Cassidy et al. performed genome-wide DNA analysis on two Middle stone and 42 Neolithic individuals from multiple burial environments , including caves, tunnel tombs and other types of burial buildings. Previous studies have obtained DNA data from 16 individuals from the Neolithic period (about 4000-2500 BC) and the early Bronze Age (2200-1500 BC), as well as DNA data from prehistoric individuals from the United Kingdom and continental Europe. By combining these results with their own data, Cassidy and others give a big picture of their findings.
Their findings touch on important issues such as the isolation of the Middle Stone Age population in Ireland, the migration of Neolithic farming populations, and the relationship between these farming populations and the First Irish people who lived on fishing and hunting in the Middle Stone Age. Cassidy et al. also identified whether there was a genetic link between farmers buried according to specific customs between 4000 and 3000 BC. In addition, they obtained data on carbon-14 and stable isotopes for 27 individuals, which provided information about their diet.
At The Killuragh Cave in Limerick, south-west Ireland, and Sramore Cave in County Litrim in the north-west and Stoney Intheri, in the west, scientists obtained genetic data from human remains of about 4700 BC and about 4100 BC, the earliest known DNA data of Irish fisherhunters. These Middle Stone Age Irish were genetically distinct from the British “neighbors” across the Irish Sea at the same time, suggesting that the group had a long period of genetic isolation when they arrived in Ireland about 8,000 BC. In other words, although members of this group may have ranged from choosing mates to most of Ireland, they did not return to the UK or go to continental Europe to meet people there – contrary to the views of some archaeologists. Thus, there is no evidence to support the assertion by some archaeologists that the farming life of the Neolithic population that will become a Neolithic feature has been brought to Ireland.
Instead, Cassidy et al. discovered new genomic features by analyzing human remains from the Poulnabrone stone shed tomb in County Clare, western Ireland, where the single-chamber tomb building has tall stones erected at the entrance and a large roof stone above it. This means that at least as early as 3800 B.C., people from other places came to Ireland, which in turn coincides with the idea that new immigrants introduced agriculture into Ireland. This group is genetically related to the Neolithic population in Britain, and their ancestors came from continental Europe. Either way, these immigrants had a significant impact on small, isolated indigenous populations in Ireland’s Middle Stone Age, whose genetic characteristics disappeared almost a few generations later. However, DNA evidence from the Parknabinnia Courtyard Tomb in County Clare, a type of burial building with segmented chambers and a forecourt, suggests that there was indeed mixed blood between local and foreign groups (possibly until 3750-3500 BC). As a result, it is clear that indigenous populations have not completely disappeared.
After analyzing individuals from different burial environments from 4000-2500 BC, Cassidy et al. clarified the population dynamics and kinship of neolithic humans in Ireland. Among those buried in the early Neolithic courtyard tombs and stone sheds, the team found an presumably a fourth-level relationship at the Parknabinnia tomb, and a man buried there and two men buried at poulnabrone’s tomb, 7 km away, found a longer kinship. In addition, an earlier study of the Primrose Grange Courtyard In Sligo, in north-west Ireland, found that a Neolithic father and daughter were found. Excluding these examples, the general situation at the time was that genetics made different groups using the same graveyard, which meant that human settlements had reached a considerable scale.
However, Cassidy et al. found that their kinship spanned considerable geospatial and several generations from about 3500-2500 BC to people buried in the Passage Tomb (and a similar but different burial building in Millin Bay, County Down, Northern Ireland). People buried in passage tombs seem to be a little different from those in other types of graves: they are particularly meat-rich in their diet.
Cassidy et al. have found genetic links between individuals buried in the Carrowmore and Carrowkeel passage tombs in Sligo County, 150 km away, in the Boin Valley (and Millin Bay’s burial). They interpreted the evidence as that the choice of partner at the time was from a larger area and was non-random, which in turn meant that the complexity of society had reached a relatively high level. There is a view that the trajectory of the Irish Passage Tomb (in short, from small to simple to large and public) reflects the growing class division in society, a view supported by genetic data from Cassidy’s team. The case of Newage’s tomb is an example of the existence of upper classes that sustain seisimake, which is consistent with the broader framework of the above theory.
Cassidy et al. have many other exciting insights, including the possible color of the skin, hair and eyes of ancient people, and the world’s first case of Down’s syndrome (3629-3371 B.C.), which occurred in a baby boy buried in the tomb of Poulnabrone. However, their research is also controversial, especially with the use of terms for social evolution. In the case of those societies that built the tombs of the main passages of the Boyne Valley, for example, it would be problematic to say that they had the characteristics of early state societies and their predecessors (e.g. bureaucracy, centralizedism, etc.).
Moreover, in terms of Cassidy’s et al.’s emphasis on the genetic relationship between Irish and British Neolithic farming groups and those in the Iberian Peninsula (Spain and Portugal), they seem to have made the mistake of assuming that Irish farmers originated in Iberia – a view that is not supported by archaeological evidence. As to the origin of Irish farming emigration, the current evidence points to the Opposite the Morbyon region of Brittany in north-west France and the North Calais Channel region in the north, where groups from the latter are most likely entering Ireland through the north of England. A recently published DNA analysis of French Neolithic farmers supports this finding that some individuals have components of the “Iberian” or “Mediterranean” genetic characteristics. But there are still many missing plates in the genetic puzzle, and more French Neolithic individuals need to be analyzed to solve the problem of the origin of Ireland’s earliest farming populations. In any case, Cassidy et al.’s valuable essays provide us with a wealth of thought-provoking and discussed content for our study of the prehistoric society of Ireland.