Testosterone is significantly correlated with aggression and competitive behaviour and is directly facilitated by the latter. There are two theories on the role of testosterone in aggression and competition.  The first one is the challenge hypothesis which states that testosterone would increase during puberty thus facilitating reproductive and competitive behaviour which would include aggression.  Thus it is the challenge of competition among males of the species that facilitates aggression and violence.  Studies conducted have found direct correlation between testosterone and dominance especially among the most violent criminals in prison who had the highest testosterone levels.  The same research also found fathers (those outside competitive environments) had the lowest testosterone levels compared to other males. 
Did Christianity usher in the dark ages? The term ‘dark ages’ has not been defined by the questioner but it commonly refers to the cultural and economic deterioration that occurred in Western Europe after the fall of the Roman Empire. There are normally two aspects to what might be termed the ‘Christianity guilt thesis’; firstly that Christianity was a significant contributing factor to the decline and fall of the Roman Empire and secondly that the new religion was hostile to classical learning and did not foster and preserve enough of it as the empire collapsed.
Eventually I ran out of my 10-day prescription and thought I no longer needed any meds. But without them, I backslid. I became overly ambitious about what I could do--like get out of bed--and ended up in more pain. I needed more muscle relaxers and anti-inflammatories, but my client was out of the country. So I went back to the new doctor and explained what happened two days after I saw him. He put me on a "better" muscle relaxer (Carisoprodol) and anti-inflammatory (Naproxen). The new muscle relaxers did not make me at all drowsy. I liked being drowsy enough to fall asleep. I felt the original one did a better job for me personally. And I wasn't sleeping well.