A new analysis of the locations and ages of ancient farming sites reinforces the controversial idea that the groups that started raising crops in the Middle East gradually grew in number and colonized much of Europe, replacing many native hunter-gatherers in the process.
Hunter-gatherers in some European locales may have adopted farming rather than surrender their home territories to the newcomers. Overall, though, the data indicate that newly arrived farmers reproduced at a rate high enough to keep their boundary moving steadily northwestward at roughly 1 kilometer per year, say anthropologist Ron Pinhasi of Roehampton University in London and his colleagues.
One of Pinhasi's coauthors, Albert J. Ammerman of Colgate University in Hamilton, N.Y., proposed much the same scenario more than 30 years ago with Stanford University's L. Luca Cavalli-Sforza. Their wave-of-advance model rested on an analysis of 53 farming sites.
Pinhasi's team considered the geographic arr