I have expanded the history of haplogroup E1b1b with a new theory about the origin of E1b1b in Europe. The absence of E1b1b in Neolithic sites so far raises new questions to which I hope to find the answer. Here is the text :
It is still unclear when haplogroup E entered Europe. Recent DNA tests from Neolithic sites in southern Germany and southern France lacked all trace of E1b1b. This suggests a later arrival, either towards the end of the Neolithic/Chalcolithic or during the Bronze Age. In the absence of Y-DNA from Neolithic Greece, South italy and Iberia, nothing rules out the possibility that E1b1b was present to these regions since the Neolithic, Mesolithic or even the late Paleolithic. North Africans carriers of E1b1b could have crossed the Mediterranean (probably in several independent waves) anytime between the Last Glacial Maximum (circa 20,000 years ago) and the last desertification of the Sahara that started when the monsoon retreated south 6,200 years ago.
At the Last Glacial Maximum, sea levels were 120 metres lower than today and the Strait of Gibraltar was just a few kilometres wide, permitting even the most primitive raft to cross it easily. Is it merely a coincidence that the last attested trace of Neanderthal in Iberia (actually in Gibraltar itself) dates from 24,000 years ago, a short time before the Last Glacial Maximum ? Could their disappearance be the result of an an absorption by Homo Sapiens from North Africa ? The last Iberian Neanderthals did show some signs of hybridization with Homo Sapiens. Whereas Homo Sapiens indisputably colonised Europe from the Middle East, a counter-current colonisation from Northwest Africa is plausible too. This would explains why there is so much Northwest African E-M81 in Portugal and Northwest Spain, which is not corroborated by any historical migration nor by any archaeologically demonstrable Neolithic migration from Northwest Africa.
The Sahara changed many times from a lush green place to a hot and arid desert in the last 20,000 years. It was as arid as today at the end of the last Ice Age 13,000 years ago, then the warming climate brought tropical monsoons again from 10,000 to 7,000 years before present. The desertification taking place today started around 4,200 BCE. This severe transformations of their environment surely had a tremenfous effect on the indigenous (E1b1b) people, causing populations booms during the green millennia of the Neolithic, and prompting migrations to milder climes once the rain had gone. It wouldn't be all that surprising that North Africans crossed the Mediterranean (again ?) in the late Neolithic. The region most affected by the desertification would have been around modern Libya. The northern Maghreb enjoys the protection of the mountains that stopped the advance of the desert. Egypt had the Nile and its delta. One hypothesis is that the Neolithic population of Libya migrated to what is now South Italy, Greece, Macedonia and Albania, bringing with them the E-V13 lineage, which is still found in Libya today, as well as in Iberia, Egypt and the Levant, but is far more common around Greece. Alternatively, instead of crossing directly the Mediterranean from Tunisia to Sicily, then to Italy and the southern Balkans, the migration could have taken place along the coast of the Mediteranean, through Egypt, the Levant and Anatolia, and eventually to Greece. Some migrants might have taken a westward route to Iberia, explaining why E-V13 is found in western Iberia, alongside the Maghreban E-M81, while Greeks never colonised that region.