and wealth creation
has been an exercise of more and more specialisation
in the economy
At first, everyone fended for themselves. Then, with the founding of cities and empires, people began to acquire expertise. Once the physiological needs of a populace were secure, others could start to work on professions. At first, we had people who became experts at still quite general areas, such as "building houses". Today it is recognised that it takes many different professionals to build a house.
The expertise that specialisation grants people leads to much higher efficiency and output per head. The classic story of the pin factory Adam Smith used as an example shows the massive advantages of specialisation. A factory that was churning out only a few pins a day was turned into a productive dynamo when everyone had their own task to accomplish efficiently.
There is, however, a trade-off. Although specialisation has enabled society to advance a lot quicker, it generally causes a decrease in motivation in the work-place. People get bored carrying out the same task over and over again - the efficiency granted by specialisation is usually a bigger boon than this downside, however.