And it is an interesting point, though. The 'welfare state' does give a security and longevity to people who would otherwise be too weak or too stupid to survive. Where nature would have them eliminated (by 'natural' causes or by being destroyed by fellow beings) due to those defects, you would essentially be weeding out such defects from the gene pool over a period of time, possibly leading to a 'naturally' stronger species while at the same time, it could be argued that the said 'welfare state' provides security so that those who are physically weaker but mentally superior, or mentally inferior but physically superior survive, so thus leading to a stronger species in different ways.
The many many generations that were born and died prior to the welfare state existing would suggest that these undefined traits you feel are not being bred out seem to be quite resilient...
If the welfare state is responsible for keeping such "defects" going in the gene pool how did they manage to survive up to the point that the welfare state was introduced?