The Neolithic: Boom time machine. A new technique lets archaeologists reconstruct the past in greater detail. THAT economic expansion leads to building booms seems to have been as true 6,000 years ago as it is now. When agriculture came to Britain, it led to a surge of construction as impressive and rapid as the one that followed the industrial revolution. Which is all a bit of a surprise to archaeologists, who had previously seen the arrival of the Neolithic as a rather gentle thing. But that may be because of the tools they use. Radiocarbon dating provides a range, often spanning 200 years or more, rather than an exact date for a site. Stratigraphy, which looks at the soil layers in which artefacts are found, tells you only which ones are older and which younger. None of these data is precise. They do, however, limit the possible range of dates. And by using a statistical technique called Bayesian analysis it is possible to combine such disparate pieces of information to produce a consolidated estimate that is more accurate than any of its components. That results in a range that spans decades, not centuries. A team led by Alex Bayliss, from English Heritage, a British government agency, has just used this technique to examine digs from hundreds of sites around Britain. The results have caused them to reinterpret the Neolithic past quite radically.