The diversity of genotypes in populations resulting from the action of evolutionary prerequisites leads to the appearance of phenotypic differences between individuals. As a result of the struggle for existence, individuals survive in each population and leave offspring with phenotypes useful in this environment. And if in a series of generations natural selection will retain only such phenotypes, then a directed change in the gene pool of the population will occur.
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.