Oppenheimer tries to use Linguistic research as an extra yardstick to help him with some of his theories, but steers well clear of using it for ANY dating at all, and generally only seeking larger patterns which may support his theories. He did write a book regarding human migration prior to the last ice-age, but this book deals with post ice-age movements and almost exclusively within Europe. Even those are heavily caveat laden, so in short he's a bit timid when it comes to even referring to language. However he did stretch his neck out a bit to say that he reckons that germanic influences were pretty noticeable in England hundreds of years prior to the Saxon 'invasions', due to a great deal of trading and cross cultural pollination across the north sea, our traditional focus and hub prior to the norman invasion. aaanyway, you're more than welcome to borrowage if you like.