Imagine the following situation:
A society develops where the rich have more children which survive than the poor either because they can economically provide for them or because they can afford health care, etc. Imagine then that when the rich die, they give most of their money to their offspring (as opposed to their spouses, etc) thus giving their offspring a good headstart in life.
Such a society would, over the course of a number of generations, be populated by the genes of economically successful people. (That is, one could trace their linage back to someone who was wealthy) Now its not possible to isolate a "rich" gene as such, but purely from a survival of the fittest and evolutionary perspective we can imagine the characteristics which lend themselves to economic success would become refined in such a society where the rich have more "effective" children than the poor.
Such a scenario is not purely a though experiment but may be a causal contribution to the end of the period of human existence before the 1800 where on average the income and total infrastructural investment of the world was very low. (That is to say, there were no paved roads, railroads, airports, piped water, electricity, sewerage, etc)
The society in question was Great Britain in the Middle Ages (1400-1800) where they have studied the wills of the poor and rich and found that the rich were more willing to give to their siblings as opposed to the poor, but the poor were more likely to give to charities. The poor also had less surviving siblings than the rich too.
This is a field of research known as Evolutionary Economics which tries to explan from an economics point of view the rapid capitalisation and scientific development which has occured during the past couple of hundred years. (Gregory Clark at Beyond Belief 2)
If true, it has a few alarming consequences, but could also solve some pressing social issues...
Australians are familiar with the divide between the native Aboriginal Australian's and those of European heritage. Some Aboriginal communities are on par with Third World countries even though Australia is a First World country. Evolutionary Economics would explain why the Australian Aboriginals are unable to assimilate into a modern world. It may not just be a cultural problem, but could be due to genetic distribution problems which make Aboriginals more suited to their hunter, gatherer past as opposed to those genes which make people economically sucessful.
If true, we may be wasting our time in trying to force them to assimilate because they may not be able to. We are arrogant to assume that assimilation would be better because its not possible to show that our modern society is somehow more progressive, humane or better than a hunter, gatherer and sustainable society. Some have argued that we have done a disservice to humanity in moving to cities and forming civilizations because we have been tuned to be hunter gathers for the better part of 100 to 200 thoundand years.
Now I put the following situation on the table.
Imagine if smart people have less children than dumb people. What would happen to the population after a few generations?