Over time, carbon decays in predictable ways. And with the help of radiocarbon dating, researchers can use that decay as a kind of clock that allows them to peer into the past and determine absolute dates for everything from wood to food, pollen, poop, and even dead animals and humans. While plants are alive, they take in carbon through photosynthesis. Humans and other animals ingest the carbon through plant-based foods or by eating other animals that eat plants. Carbon is made up of three isotopes.
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Anything that was once alive or that was produced by a living thing can be dated by using the radiocarbon method of dating. This method, which received widespread attention in connection with the Dead Sea Scrolls, relies on the fact that all living things take in carbon, some of which is very slightly radioactive. But just how reliable is this method? To hear some people tell it, scientists have nearly absolute confidence in the dating methods they use.
Radiocarbon helps date ancient objects—but it's not perfect
The ability to precisely date, or identify the age of an object, can teach us when Earth formed, help reveal past climates and tell us how early humans lived. So how do scientists do it? Radiocarbon dating is the most common method by far, according to experts. This method involves measuring quantities of carbon, a radioactive carbon isotope — or version of an atom with a different number of neutrons.
That its just guesses. Is he right or how do they deemine how long ago the dinosaurs were? If it's an actual bone, and not a fossilized bone, then carbon dating is the ticket.