This thread lead me to a bit of googling, wasted about three hours reading about why we dont have 3 trillion ancestors and the like(interbreeding is the short answer)!
One interesting concept to pop up was the idea of the 36 clan mothers, so I’m having a guess this will as far back as I could get with mine, some burd called Tara from 15,000 BC! 😀 I’ve never did the DNA sequencing mind, just guessing the most likely from the descriptions….
http://www.oxfordancestors.com/content/view/35/55/
The clan of Tara
(Gaelic for rocky hill)
includes slightly fewer than 10% of modern Europeans. Its many branches are widely distributed throughout southern and western Europe with particularly high concentrations in Ireland and the west of Britain. Tara herself lived 17,000 years ago in the northwest of Italy among the hills of Tuscany and along the estuary of the river Arno.