Plants take in atmospheric carbon dioxide by photosynthesis, and are ingested by animals.
Free 5-day trial Ever wondered how scientists know the age of old bones in an ancient site or how old a scrap of linen is?
The technique used is called carbon dating and in this lesson we will learn what this is and how it is used. Carbon dating, or radiocarbon dating, is a method used to date materials that once exchanged carbon dioxide with the atmosphere. In the late 1940s, an American physical chemist named Willard Libby first developed a method to measure radioactivity of carbon-14, a radioactive isotope.
The amount of carbon-14 gradually decreases through radioactive beta decay with a half-life of 5,730 years.
So, scientists can estimate the age of the fossil by looking at the level of decay in its radioactive carbon.
At high geomagnetic latitudes, the carbon-14 spreads evenly throughout the atmosphere and reacts with oxygen to form carbon dioxide.
Carbon dioxide also permeates the oceans, dissolving in the water.
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A child mummy is found high in the Andes and the archaeologist says the child lived more than 2,000 years ago.
How do scientists know how old an object or human remains are?
Because atmospheric carbon 14 arises at about the same rate that the atom decays, Earth's levels of carbon 14 have remained fairly constant.