How does “Carbon Dating” work?
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Carbon is the primary ingredient for all life on Earth. It forms key molecules like protein and DNA. Plants use it for photosynthesis. It also facilitates energy storage in the form of carbohydrates and lipids. Carbon makes up approximately 50% of all biomass on Earth.
All living beings are constantly exchanging carbon atoms with the environment. Once they die, this cycle stops and all carbon atoms in the body remain where they are.
Now, there is one special kind of carbon atom called radiocarbon, or carbon-14. This atom is radioactive, and is constantly decaying. We know the rate at which it decays (50% in about 5,730 years, also known as its half-life).
Say the ratio of carbon-14 to regular carbon in the atmosphere is 2%, which means that when a certain organism was alive, 2% of all carbon atoms in its body were carbon-14.
We can do the same measurement today, and find that after decay the number is actually 1.5%. So, doing some math we can figure out what percentage of c14 atoms have decayed from the body, and so figure out an approximate age since the decay started.
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