After death, the carbon-14 decays with a half-life of about 5,730 years, and the dwindling ratio serves as a time stamp.
Libby's team proved the accuracy of this 'clock' on objects of known age, such as Egyptian mummy tombs, and bread from a house in Pompeii, Italy, that was burned during the eruption of Vesuvius.
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.
At university, he planned to study geography and glaciology, but switched to archaeology after excelling in an introductory course taught by his father that he had signed up for on a whim. “I got less and less interested in archaeology because it was so subjective and woolly.” The reasons for that woolliness were partly technical and partly historical, dating back to before the Highams' time.
Archaeology before carbon dating relied on two principles: older things are buried beneath younger things, and people with cultural ties make similar-looking objects, such as stone tools. In the early nineteenth century, the Danish historian Rasmus Nyerup wrote that most of early human history was “wrapped in a thick fog”.
“It is another sobering example of cocked-up dates,” says Higham, whose laboratory is leading a revolution in radiocarbon dating.
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.Then, in the twentieth century, carbon dating found the bones to be about 22,000 years old — even though much of Britain was encased in ice and seemingly uninhabitable for part of that time.When Higham eventually got the bones, his team came up with a more likely scenario: they were closer to 33,000 years old and one of the earliest examples of ceremonial burial in Western Europe.Tom found himself drawn to the quantitative side of archaeology to help fill in those details.His father had counselled that if he wanted a future in the field, Tom ought to join the push to make it a more rigorous science, emphasizing testable theory, experiment and statistics.