This story in today's UK Independent describes a paper by archaeologist Paul Mellars which attempts to explain the sudden expansion of homo sapiens around 60,000 years ago. No doubt there are other reports, but I thought I would just note this one while it is fresh.

Added: There is a similar report in the UK Times. This mentions that Mellars's paper is in Proceedings of the National Academy of Sciences of the USA, online. I checked out the PNAS website, but couldn't find it yet. If anyone has better luck, please mention it in Comments.

Added #2: Dienekes has an abstract of the PNAS article.