The developement and arrival of Aurignacian culture to Europe was maybe a definitory moment. Most likely it was carried by the oldest Homo sapiens ever to step in the continent and these are our ancestors, at least our ancestors with the oldest roots here (others may have arrived later on).
Which are the exact origins of this culture seems to have arisen some scholarly disputes and the last word may not have been said yet. But the last years have provided some interesting papers that seem to be largely coincident. I'm mentioning three of them here:
1. M. Otte and J.K. Kozlowski, Constitution of the Aurignacian through Eurasia (2004): This is a brief paper that suggests that the Aurignacian evolves into its finished more characteristic European form as it marches into the West. Its origins could be somewhere in the Middle East or Central Asia, with related sites in Iraq, Iran, Uzbekistan, Afghanistan and even remote Altai. The Bacho-Kirian of Bulgaria is a precursor of finished European Aurignacian.
2. J.K. Kozlowski, A dynamic view of Aurignacian technology (2006): A larger and more technical paper. Kozlowski analyzes here the correlations between Bacho-Kirian (Bulgaria), Ahmarian and Emirian (Palestine and Lebanon) and well defined European Aurignacian, as well as transitional cultures (proto-Aurignacian). For him "Mediterranean" proto-Aurignacian is more directly connected to Ahmarian than to Bacho-Kiro but typical Aurignacian is rather a derivation of Bachokirian itself.
... the analysis of production techniques in regions remote from one another (Poland, France) indicates similarity of technology within the Typical Aurignacian. This technology derived from the Initial Upper Palaeolithic, known as the Bachokirian in southeastern Europe.3. P. Mellars: Archeology and the Dispersal of Modern Humans in Europe: Deconstructing the 'Aurignacian' (2006): For Mellars Aurignacian originates in Ahmarian (Near East), being Bachokirian an intermediate step. He also suggests two routes for the penetration of Aurignacian in Europe.
But more interestingly, Mellars reveals that recent studies allow for much more precise calibration of existing radiocarbon dates, pushing the arrival of Aurignacian to Europe back by some 5,000 years. Aurignacian colonists would therefore have arrived to most of Europe, roughly 42-41,000 years BP (calibrated) or, in other terms, some 40-39,000 years BCE.
He also provides a nice map: