The carbon in their bodies at the time of their death will remain in their bodies until they decompose, or if they become fossilized, then forever. This allows scientists to look at the amount of decay in a fossil’s radioactive carbon and determine a relative date.
Radiocarbon dating is only effective for objects and fossils that are less than 50,000 years old.
Carbon is the 15th most abundant element in the Earth's crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen.
Carbon's abundance, its unique diversity of organic compounds, and its unusual ability to form polymers at the temperatures commonly encountered on Earth enables this element to serve as a common element of all known life.
Familiar to us as the black substance in charred wood, as diamonds, and the graphite in “lead” pencils, carbon comes in several forms, or isotopes.
When these lifeforms die, they stop taking in new carbon.
Graphite is a good electrical conductor while diamond has a low electrical conductivity.
Under normal conditions, diamond, carbon nanotubes, and graphene have the highest thermal conductivities of all known materials.
It is the second most abundant element in the human body by mass (about 18.5%) after oxygen.
The physical properties of carbon vary widely with the allotropic form.