Here's why:
* Radioactive Decay: Carbon-14 is a radioactive isotope of carbon that decays at a known rate. This decay rate is called its half-life, which is approximately 5,730 years. This means that after 5,730 years, half of the original amount of Carbon-14 in a sample will have decayed into Nitrogen-14.
* Absorption in Living Organisms: While living organisms are alive, they continuously absorb Carbon-14 from the environment. This keeps the ratio of Carbon-14 to Carbon-12 in their bodies relatively constant.
* Decay After Death: When an organism dies, it stops absorbing Carbon-14. The Carbon-14 in its remains then begins to decay at a steady rate.
* Measuring Decay: By measuring the remaining amount of Carbon-14 in a sample and comparing it to the original amount, archaeologists can determine how long ago the organism died. This method is known as radiocarbon dating and is effective for dating organic materials up to around 50,000 years old.
It's important to note that Carbon-14 dating is a powerful tool but has limitations. It can only be used on organic materials, and the accuracy of the dating is affected by various factors, such as the sample's age, preservation, and environmental conditions.
