Five thousand, two hundred years ago, long before Stonehenge, long before the Pyramids, farming communities in the Boyne Valley of Ireland built a gigantic passage tomb, called Newgrange . It covers 4,500 square metres, or more than one acre, of ground. The builders heaped alternating layers of stone and earth until it was 12 metres high.
Every year, on the winter solstice, a shaft of sunlight pierces a passage formed by gigantic stone slabs which illuminates a chamber 19 metres within. Archaeologists have found human remains, some cremated, in the passage.
Newgrange is just the best preserved of a number of Neolithic tombs scattered across the Irish landscape. Another is the Poulnabrone portal tomb , in County Clare, on the other side of the island, which was probably built before Newgrange, between 4200 and 2900 BC. The remains of 22 people – 16 adults and six children — were discovered beneath it by archaeologists in the 1980s.
Who constructed these monuments? Why?
Whoever they were, they left no written records, just elaborate art motifs scribed into sandstone or limestone slabs. But genetic detective work just published in the journal Nature  opens a window onto the human drama of these ancient peoples.
First of all, the skull of a male interred at Newgrange’s inner chamber points to first-degree incest: he was the offspring of brother and sister or perhaps parent and child. For the archaeologists this was an amazing find.
Inbreeding is a near universal taboo across continents and centuries. It only happens among ruling elites – typically within a deified royal family. It was customary in Hawaii, the Inca Empire and ancient Egypt. By breaking the rules, archeologists hypothesise, an elite separates itself from the general population, intensifying hierarchy and thereby legitimizing its power. Extravagant monumental architecture often co-occurs with dynastic incest. A faint echo of this is found in the mediaeval Irish name for one of the passage tombs, Fertae Chuile, or “Hill of Sin”.
Second, and more relevant to our own times, is the genetic analysis of the people buried in Poulnabrone. Previous investigations suggested that they, too, were members of an elite. Judging from the manpower and organisation required to build a portal tomb, they must have ruled over a numerous and fairly sophisticated society. Even so, their lives were tough. Only one adult had lived past the age of 40. They suffered bouts of infection and malnutrition. They lived with violence. One individual may have died after being struck by an arrow; another had a crushed skull; still another a rib broken by an aggressive blow.
It sounds like Thomas Hobbes’s classic description  of the lives of men in a state of nature: “solitary, poor, nasty, brutish, and short”.
Don’t believe that old cliché. These Neolithic people could teach us a thing or two about human dignity – as the archaeologists discovered when they examined the genome of PN07.
PN07 – we’ll never know what name his mother gave him – was a male infant with Down syndrome. He is, the archaeologist proudly report, “the earliest definitive discovery of a case of Down syndrome”. Up until now, the earliest remains of an individual with Down syndrome dated from the 5th or 6th Century in France. Furthermore, genetic analysis reveals that PN07 had been fed from his mother’s breast.
What does this suggest?
The lives of these Neolithic people were harsh beyond our comprehension. Every day was a struggle to survive. They battled wild animals, disease, injuries, rival tribes, the weather, hunger. A Down syndrome boy must have been a heavy burden on their scarce resources. His tribe or clan must have known that he would never be a warrior and that he would not live long. Yet they nurtured him as best they could. They made him feel loved. And when he died they treated his body with the dignity due to the child of an elite household.
If the true measure of a society is to be found in how it treats its most vulnerable members, the Poulnabrone people were civilised.
Indeed, they compare favourably, very favourably, with us. We abort at least 90 percent of all of our Down syndrome babies – even though research shows  that 99 percent of parents with Down syndrome children love them and 97 percent are proud of them.
Perhaps we can learn something from the 5,000-year-old tenderness of PN07’s mum.