Final answer:
The division of time into stages is managed by historians, scientists, and organizations like the International Commission on Stratigraphy, using events that signal significant changes in the Earth's condition for the geologic time scale. The four stages of eons are the Hadean, Archean, Proterozoic, and Phanerozoic. Additionally, the demographic transition outlines four stages of population change related to technological and social developments.
Step-by-step explanation:
The division of time into stages based on technological developments and changes has been a collective effort of historians, scientists, and organizations such as the International Commission on Stratigraphy. Significant events in Earth’s history, particularly those that mark major changes in geology, climate, or the evolution of life, have been used to define these stages. For the geologic time scale, these are broadly categorized into eons, eras, periods, epochs, and ages, with the four stages of eons being the Hadean, Archean, Proterozoic, and Phanerozoic. The first three are often collectively referred to as the Precambrian. The classification system is refined continuously as new data arises, primarily obtained through radiometric dating techniques.
The socio-demographic 'stages' are related to the demographic transition, which describes how populations grow and change over time, traditionally divided into four stages. This model outlines how societies move from high birth and death rates to low birth and death rates through different technological and social developments.