All are afflicted

Genetic studies seem to show that the branch of human primates began when a mutated gene resulted in weaker muscles rather like a genetic disease. This allowed for the brain case as an attachment point for jaw muscles to have thinner walls and be able to grow larger. The timing of the mutation and the fossil record seems to have a nice coincidence.

Update: Essentially what this means is that a key genetic mutation that gave rise to hominids would have been expressed as a muscle-atrophying disease. Clearly the social structure of the pre-hominids in which this emerged must have been able to provide nourishment and protection for these weaker individuals sufficient for them to pass on the defect to subsequent generations. Here we have a case where culture was the adaptation that insured survival rather than genetics. This triggers a couple of questions. In today's world, has culture now become the primary player in the progress of man? And if culture can provide cover for the propagation of mutations that are culturally advantageous rather than physically advantageous perhaps we should be paying more attention to other mutations that appear today as diseases. They may be the harbingers of what changes the species may undergo in the future.