An archaeologist’s staple is radiocarbon dating: judging the age of an organic sample from its carbon-14 – also known as radiocarbon – content.

Around 99% of carbon on earth is carbon-12 – atoms with six protons and six neutrons in its nucleus.

Scratching around in a cave in the middle of nowhere, you find a bone.

How do you find out if it’s the remains of an ancient animal that stomped the land tens of thousands of years ago or a discarded scrap from a cooking fire only a few hundred years back?

In order to date copper-containing, archaeological finds, a team led by Antonio Doménech-Carbó at the University of Valencia examined the ratios of two different copper oxides, tenorite and cuprite, that can be differentiated and quantified based on their voltammetric curves.Today, many different radioactive elements have been used, but the most famous absolute dating method is radiocarbon dating, which uses the isotope C.This isotope, which can be found in organic materials and can be used only to date organic materials, has been incorrectly used by many to make dating assumptions for non-organic material such as stone buildings.How can the age of archeological objects be determined if the well-established carbon dating method does not apply, for example for metal objects?Spanish and Portuguese scientists have now introduced a technique for dating artifacts made of copper and bronze.Based on a discipline of geology called stratigraphy, rock layers are used to decipher the sequence of historical geological events.Relative techniques can determine the sequence of events but not the precise date of an event, making these methods unreliable.Then, only exceptionally well-preserved, pristine samples can provide reliable dates.At Warratyi rock shelter in the Flinders Ranges, South Australia, which shows signs of the oldest human occupation of the country’s arid interior, the oldest sample – a fragment of emu eggshell – has been radiocarbon dated to 49,000 years with reasonable confidence.There are two main categories of dating methods in archaeology: indirect or relative dating and absolute dating.Relative dating includes methods that rely on the analysis of comparative data or the context (eg, geological, regional, cultural) in which the object one wishes to date is found.Radiocarbon is an isotope with two extra neutrons, created by cosmic rays interacting with nitrogen in Earth's atmosphere.When a plant or animal is alive, it constantly replenishes trace amounts of radiocarbon in its tissues.On the other hand, absolute dating includes all methods that provide figures about the real estimated age of archaeological objects or occupations.These methods usually analyze physicochemical transformation phenomena whose rate are known or can be estimated relatively well.