That said, they're using Carbon-14 dating on recent human remains in forensic science , although the technique works best on bodies around the 1940s to 1960s due to the increased presence of C-14 due to atomic bomb testing.
Currently, the atmospheric levels of C-14 are dropping again, so the method will be less feasible for people deceased after that point.
Because of its extremely long half-life (over 5,000 years), carbon 14 content has typically been used to date only very old artifacts or fossils.
The method has traditionally failed to resolve dates of samples that differ in age by less than a few hundred years—accurate enough perhaps to date the youngest and oldest parts of the most ancient redwood trees, but not to tell how many newborn cells might be present in the human brain.
A friend of mine told my wife that carbon dating is unreliable because it has been performed on live humans and indicated that the test subject(s) are 4000 years old. Typically several forms of analysis are used on the objects and surrounding sediment in order to get multiple confirmations and greater accuracy.
Most dating used to determine age for bones/artifacts/etc that are expected to be over 50k years is done through means other than carbon-dating like Thermoluminescence, Tephrochronology, Magnetostratigraphy, etc.
In today’s Cell, Frisen and colleagues report how they used the dating method to dismiss the possibility that neurogenesis takes place in the adult human cortex.
But the almost tenfold increase in atmospheric C14 that peaked around the mid-1960s has been followed by a rapid decline since the nuclear test ban treaties and the cessation of high-yield, above-ground nuclear tests.
In fact, C14 is assimilated so rapidly that from about 1963, its half-life in the atmosphere has only been about 11 years.
Analysis of growth rings from pine trees in Sweden shows that the proliferation of atomic tests in the 1950s and 1960s led to an explosion in levels of atmospheric carbon 14.
Now, Jonas Frisen and colleagues at the Karolinska Institute in Stockholm have taken advantage of this spike in C14 to devise a method to date the birth of human cells.