What does the history of developed countries indicate about the shifts that have taken place between sectors?

The history of developed countries indicates that there have been significant shifts between economic sectors over time. Initially, the primary sector (agriculture and natural resource extraction) was the most important, with most people employed in this sector. As agricultural methods improved, food production increased, allowing people to engage in other activities, leading to a rise in crafts, trade, and other services.

Over a long period, particularly with the advent of new manufacturing methods, the secondary sector (industrial manufacturing) became dominant. People who had worked in agriculture moved to factory jobs, making the secondary sector the most important in terms of production and employment.

In the past 100 years, there has been a further shift from the secondary to the tertiary sector (services) in developed countries. The service sector has become the most important for total production and employment. Thus, the pattern observed is a progression from primary to secondary to tertiary sectors as economies develop.