'While these new techniques and technologies are uncovering secrets of the past that would have been unimaginable even a decade ago, they are throwing up as many questions as answers...' Manchán Magan writes for Culture about his new TG4 docudrama series, DNA Caillte, and the scientific teams in Irish universities uncovering startling new revelations about our past.
The past is an unknown world and yet our understanding of it is being transformed by science, as breakthroughs in the fields of DNA sequencing, forensic analysis, osteo-archaeology, palaeo-ecology and climate history reorient our perception of the ancient world. From the study of dusty remnants in dimly-light archives and fragile old tomes, history is now being spear-headed by white-coated technicians in high-tech labs.
By far the most cutting-edge field is the study of ancient DNA, which allows scientists to unravel complex molecules containing the biological instructions that drive the existence of every living organism. Supercomputers are enabling researchers to analyse apparent random sequences of nucleotide bases to reveal the secrets of people and creatures that came long before us, from the chewing habits of dinosaurs to the pooing habits of Stone Age man.
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A single piece of birch pitch that was chewed up and spat out in southern Denmark around 5700 years ago has enabled scientists to sequence a complete human genome – revealing that the chewer was female, with dark skin, dark hair, and blue eyes, and may have been lactose-intolerant. The gum even contained genetic material from one of her recent meals—duck and hazelnuts—along with DNA from the bacteria and viruses she harboured in her mouth.
These breakthroughs are happening in Ireland too, with scientific teams in Irish universities uncovering startling new revelations about our past. Their work is the subject of a new documentary series that I'm presenting for TG4, titled DNA Caillte. The series explores how scientific research is transforming our understanding of Irish history; offering insights into the first settlers who arrived here 10,000 years ago, and the beliefs about life and death in medieval Ireland, as well as the impact of weather on the colonisation of Ireland in the 16th century.
In the first episode, genetic researchers Prof Dan Bradley and Dr Lara Cassidy of Trinity College Dublin reveal that the first inhabitants of Ireland were dark-skinned, blue-eyed people who lived here for 4,000 years without leaving any trace on our own DNA. They were replaced by brown-eyed people, who were also dark-skinned, and came originally from the region straddling present-day Iraq, Syria and Egypt.
In an excavation site in Ranelagh, Co. Roscommon the remains of two men were found buried together with their arms around each other and looking into each other's face.
These insights are not easily garnered, but require uncovering ancient bone that hasn't been too contaminated by its surroundings, ideally a petrous bone which is the densest part of the human body and is located at the base of the skull. This is then dissolved in solution to release its DNA which gets sequenced in Korea, before being returned in the form of thousands of short strands of data, which must all be pieced back together again to make an entire human genome sequence.
"In a modern human, your genome is stored up quite neatly in twenty-three pairs of chromosomes," says Dr Lara Cassidy, "but when we try to get DNA from a bone sample these chromosomes have been broken into millions and millions of really small pieces. So, we have to extract all these tiny fragments and isolate them and then we have to sequence them all - these tiny little pieces. We try to piece them all back together to recreate the genome of this ancient person. Sort of like a very big jigsaw puzzle."
The sequenced genome can then be compared with the European database of genetic information which can reveal a treasure trove of information about a person’s health, diet, lineage, appearance and way of life.
"If you know someone's genome it’s surprising how much you can tell about them," says Prof Bradley says, "their physical makeup, their height, their eye colour, their hair colour, their pigmentation, as well as other important attributes, like diseases and how closely related they were to each other." DNA analysis is allowing us summon clear pictures of the first hunter-gatherer settlers who arrived here around 8,000BC. There were probably only a few thousand of them and they’ve hardly left any trace in the landscape, but suddenly new science is opening a window on their world.
Aerial radar mapping, forensic osteo-archaelogical techniques and DNA analysis of Roscommon burial sites offer stirring new insights into life in Ireland a millennium ago.
The series interviews archaeologists whose work from the 1980s and 1990s is getting a new lease of life, as bones excavated decades ago are now revealing new insights through DNA analysis. Some of the findings, such as those revealed by bones in the central chamber at Newgrange are changing everything we thought we knew about religion in Europe 5,000 years ago, while others offer more subtle insights, such as the DNA found at the Poulnabrone Dolmen in the Burren which reveals the remains of a child with Down’s Syndrome. This is the earliest example of Down's Syndrome anywhere on earth, but it also offers a poignant glimpse at how Stone Age farmers 5,800 years ago had the ability, resources and compassion to care for those with mental disabilities.
A recent grave excavation in Roscommon has been able to harness the new scientific methods to reveal startling insights into Irish society in the 9th century, including the seemingly widespread practise of keeping babies indoors to protect them from attack and the effect this lack of sunlight had on their health, also the general malnourishment of society and the many diseases and infections that afflicted people.
Aerial radar mapping, forensic osteo-archaelogical techniques and DNA analysis of Roscommon burial sites offer stirring new insights into life in Ireland a millennium ago, while also hinting at some strange pagan practices that continued into the Middle Ages for centuries after the coming of Christianity, such as the burial of men with large stones in their mouths, presumably to stop evil spirits re-entering their bodies and bringing them back to life. In an excavation site in Ranelagh, Co. Roscommon the remains of two men were found buried together with their arms around each other and looking into each other's face. Their position would suggest they may have been lovers, but DNA analysis reveals that the two males were distant relatives, and so it’s equally possible they were foster brothers, as the practise of fosterage was common in medieval Ireland and created an exceptionally close bond between men.
It goes to show that while these new techniques and technologies are uncovering secrets of the past that would have been unimaginable even a decade ago, they are throwing up as many questions as answers. The one thing we can be certain of is that as the science is still in its infancy many more discoveries await us in the years ahead.
In the meantime, check out DNA Caillte, Wednesday nights on TG4 for a glimpse of how our history is being rewritten by science. www.tg4.ie
DNA Caillte, TG4, Wednesdays from 2nd September at 9.30pm - find out more here.
