Scott Ladd, of York Middle School, Main, USA, asks :-

How, in your opinion, did the use of radiocarbon dating change the way scientists are able to interpret and understand history?

Tom Higham, a radiochemist at Waikato University's Radiocarbon Dating Laboratory, and who receives many questions via the web page, responded.

Before 1950, when radiocarbon dating was first developed by scientists, archaeologists had no way of knowing precisely how old (in numbers of years) an archaeological site or artefact was. In some parts of the world, where historic records extended back far enough in time, such as in the Mediterranean, archaeologists had dated artefacts by comparison with material from other sites which could be historically dated using the Egyptian calendar. This method was called "relative dating", and it is still used today.

Radiocarbon dating, developed in the late 1950s by a team led by Willard F. Libby, enabled archaeologists and other scientists to verify the ages of carbon-bearing materials independently and almost overnight revolutionised the approach of dating the past. The reason was that now any samples could be dated, so long as they were once living organisms. Radiocarbon dating is one of the critical discoveries in 20th century science and it provided one of the most important tools for archaeologists in their quest to uncover the past. Instead of spending large amounts of time solving the problem of `when' something happened, archaeologists could now concentrate on investigating `how' and `why' things happened.