For example, based on the primate fossil record, scientists know that living primates evolved from fossil primates and that this evolutionary history took tens of millions of years.
By comparing fossils of different primate species, scientists can examine how features changed and how primates evolved through time.
When a radioactive chemical is used in this way it is not normally harmful, because: Emitters of beta radiation or gamma radiation are used because these types of radiation readily pass out of the body, and they are less likely to be absorbed by cells than alpha radiation.
Radiation is used in industry in detectors that monitor and control the thickness of materials such as paper, plastic and aluminium.
Geology is the study of the composition and physical properties of rocks, minerals, gems and other related earth materials, including diamonds and crystals.
Scientists gain an understanding of the Earth's history by studying its composition.
There's a small amount of radioactive carbon-14 in all living organisms.
However, by itself a fossil has little meaning unless it is placed within some context.
The age of the fossil must be determined so it can be compared to other fossil species from the same time period.
Understanding the ages of related fossil species helps scientists piece together the evolutionary history of a group of organisms.
Carbon-14 reacts identically to Carbon-12 and is rapidly oxidised to form (Carbon-14)Dioxide.
Since all living organisms on Earth are made up of organic molecules that contain Carbon atoms derived from the atmosphere, they therefore contain Carbon-14 atoms.