Final answer:
Radiometric dating uses the half-life of isotopes like carbon-14 and uranium-238 to date fossils and geological samples, helping scientists study the Earth's history and the evolution of life.
Step-by-step explanation:
The concept of a fossil containing a radioactive element with a half-life of 4.5 million years ties into the method of radiometric dating, which is a technique used to determine the age of ancient objects. The half-life of an isotope is the time required for half the quantity of the isotope to decay to its more stable form. By analyzing the ratio of a radioactive element in a fossil to its concentration in the environment or its stable form, scientists can calculate the fossil's age. Elements like carbon-14 (14C) and uranium-238 (U-238) are commonly used for this purpose.
Carbon-14 dating is effective for dating objects up to 50,000 years old, while isotopes with longer half-lives like 40K and U-238 are used for dating older fossils or geological samples. This method helps scientists understand the ecology, biogeography, and the evolution of organisms.
The half-life of a radioactive element is a powerful tool in the field of geology and archeology, as it provides a built-in clock for dating objects and understanding historical timelines.