If you Google 'archaeologist' and 'Higham', the first hit is likely to be Charles Higham, a 72-year-old professor who has charted the origins of agriculture and government in southeast Asia.Tom was born in Cambridge, where his father was based until 1966.is a technique used by scientists to learn the ages of biological specimens – for example, wooden archaeological artifacts or ancient human remains – from the distant past. To understand radiocarbon dating, you first have to understand the word Although an element’s number of protons cannot change, the number of neutrons can vary slightly in each atom.It can be used on objects as old as about 62,000 years. Atoms of the same element that have different numbers of neutrons are called isotopes. Most carbon on Earth exists as the very stable isotope carbon-12, with a very small amount as carbon-13.It’s not absolutely constant due to several variables that affect the levels of cosmic rays reaching the atmosphere, such as the fluctuating strength of the Earth’s magnetic field, solar cycles that influence the amount of cosmic rays entering the solar system, climatic changes and human activities.Among the significant events that caused a temporary but significant spike in the atmospheric carbon-14 to carbon-12 ratio were above-ground nuclear test detonations in the two decades following World War II.Beside a slab of trilobites, in a quiet corner of Britain's Oxford University Museum of Natural History, lies a collection of ochre-tinted human bones known as the Red Lady of Paviland.In 1823, palaeontologist William Buckland painstakingly removed the fossils from a cave in Wales, and discovered ivory rods, shell beads and other ornaments in the vicinity.
As a teenager, Tom spent summers at Ban Na Di, a study site in northeastern Thailand, where his duties included helping with human excavations and brewing tea for the crew.They have the same ratio of carbon-14 to carbon-12 as the atmosphere, and this same ratio is then carried up the food chain all the way to apex predators, like sharks.But when gas exchange is stopped, be it in a particular part of the body like in deposits in bones and teeth, or when the entire organism dies, the ratio of carbon-14 to carbon-12 begins to decrease.Buckland's immediate successors did a little better.They determined that the Red Lady was in fact a man, and that the ornaments resembled those found at much older sites in continental Europe.If you ever wondered why nuclear tests are now performed underground, this is why.Most radiocarbon dating today is done using an accelerator mass spectrometer, an instrument that directly counts the numbers of carbon-14 and carbon-12 in a sample.The unstable carbon-14 gradually decays to carbon-12 at a steady rate. Scientists measure the ratio of carbon isotopes to be able to estimate how far back in time a biological sample was active or alive.This plot shows the level of carbon-14 in the atmosphere as measured in New Zealand (red) and Austria (green), representing the Southern and Northern Hemispheres, respectively.It might even explain why humans survived and Neanderthals did not.“I admire him,” says Paul Mellars, an archaeologist from the University of Cambridge, UK, and an expert on this period in Europe, for “the sheer doggedness and sense of vision” he has for improving radiocarbon dating of the Palaeolithic.