No, Dr. Lara Cassidy does not feel like Indiana Jones. Well, most days, anyway. That's what the self-described "ancient geneticist" told Ryan Tubridy on Wednesday.

Dr. Cassidy works at Trinity College, Dublin and specialises in getting DNA out of archaeological remains. Her work fuses genetics and history – and one of those things is Ryan’s favourite subject. But how, our host wondered, did Lara get involved in the world of ancient genetics? 

"I suppose genetics, anyway, is such a union between biology and history. Your genome is sort of a record of your past, just like the archaeological record is. I’m very interested in both those things, so it made a lot of sense for me."

Ancient geneticists are very particular about their bones. Which is to say, the bones of our ancestors. Lara told Ryan that she likes good-looking bones, clean and strong bones. And the best kind of good-looking, clean and strong bones is usually the inner-ear bone, the petrous temporal.

"What we do, basically, is we powderise that and we put the powder in solution and try to isolate DNA from it. And if you’re lucky, some of that DNA is going to be coming from the ancient individual in question and not bacteria in the environment." 

The Neolithic period in Ireland is defined by the arrival of agriculture and that meant farming, obviously, along with new technologies like pottery, as well as the big megalithic monuments. And it was from the remains found at one of these sites – Poulnabrone in The Burren, Co Clare – that Lara made an extraordinary discovery: 

"One of the individuals – a little boy actually – we found out he had three copies of Chromosome 21. So, he would have had Down syndrome. And, yeah, that was unexpected and quite a moving little glimpse into the world of somebody with a disability in the very, very deep past." 

Deep indeed – almost 6,000 years ago. Ancient DNA revealing, as Dr. Cassidy puts it, the diversity of the ancient past. Another, rather more famous, megalithic monument is Newgrange and fragments of remains from the burial chamber there revealed some surprising results.

So surprising, that Lara told Ryan thought she’d broken something when she saw them: "We could actually tell that his parents were either full siblings or parent and child. So, he was the son of first-degree incest." 

This was shocking to the team at Trinity College, as incest is taboo, not only to modern humans but also across almost all known human societies. So what was the theory behind this ancient Irish incest – how does something so unacceptable become acceptable? The answer, according to Dr. Cassidy, is elites: 

"It seems to be almost a way of an elite distancing themselves from the broader population. You’re obviously keeping power within a particular kin group, but there’s also a shock value to it, breaking such an innate social convention." 

You can hear Dr. Lara Cassidy’s full chat with Ryan by going here

DNA Caillte starts at 9.30pm on TG4 on Wednesday 2 September.