The ratio of normal carbon (carbon-12) to carbon-14 in the air and in all living things at any given time is nearly constant.
Maybe one in a trillion carbon atoms are carbon-14.
As you learned in the previous page, carbon dating uses the half-life of Carbon-14 to find the approximate age of certain objects that are 40,000 years old or younger.
In the following section we are going to go more in-depth about carbon dating in order to help you get a better understanding of how it works.
They found that for teeth formed after 1965, enamel radiocarbon content predicted year of birth within 1.5 years.
Since Nitrogen gas makes up about 78 percent of the Earth's air, by volume, a considerable amount of Carbon-14 is produced.
They measured carbon-14 levels in various tissues from 36 humans whose birth and death dates were known.
To determine year of birth, the researchers focused on tooth enamel.
However, at the moment of death, the amount of carbon-14 begins to decrease because it is unstable, while the amount of carbon-12 remains constant in the sample.
Half of the carbon-14 degrades every 5,730 years as indicated by its half-life.
In recent years, forensic scientists have started to apply carbon-14 dating to cases in which law enforcement agencies hope to find out the age of a skeleton or other unidentified human remains.