The Darwinian and Wallacian principle that the fittest of every generation tend to survive and have fit offspring over the longer term compared with the weakest of the generation is sill important. However, it has been more recently realized that evolution can much more quickly adjust to changing circumstances in the environment — which includes the economy as well as the natural environment.
This is achieved by sexual selection in addition to general selection. By this, the females of a species, including ourselves, choose males from as high up the ability range as possible as being more likely to be a dependable father to her children. Social status, generally, is a good guide to this natural quality control of our genes from generation to generation.
Also, all social species need clear individual leadership. This is most efficiently achieved by the emergence of a single person at the most senior social level in every organisation — political, business or religious. This usually occurs after years of a mutual sifting process throughout boyhood, adolescence and young adulthood.