Gene drift may be a consequence

* death of some individuals of the population as a result of natural selection;
* a random combination of progeny genes in a small population;
* dividing a single population into different ones as a result of isolation

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.