However, scientists can look at the decay of other elements in these objects allowing them to date them up to 2.2 billion years.
, a new species of ancient human discovered in South Africa’s Rising Star cave.
Carbon-14, or radiocarbon, is a naturally occurring radioactive isotope that forms when cosmic rays in the upper atmosphere strike nitrogen molecules, which then oxidize to become carbon dioxide.
Green plants absorb the carbon dioxide, so the population of carbon-14 molecules is continually replenished until the plant dies.
Until this century, relative dating was the only technique for identifying the age of a truly ancient object.