I stumbled across an article yesterday on Psychology Today titled "Did a Drop in Testosterone Civilize Modern Humans?" Basically, the article explains how the physical changes in Homo sapiens (skull and facial feature sizes and shapes) indicate a decrease in testosterone levels. How is this possible? Studies have proven that impaired testosterone can lead to less "masculine" features among men: less prominent brows, a rounder face, etc. Higher testosterone levels lead to more masculine features, including a longer face and more prominent brows. So, the fact that the Homo sapiens' skull and facial structure changed could very well be the result of lower testosterone levels. But the article goes on to link these changes to an increase in civilization. Before Homo sapiens, there was little in the way of tools, language, written language, agriculture, and other early technology. Some pre-historic humans went extinct before Homo sapiens developed these things. If this correlation actually did exist, it could point to some pretty interesting things about the role of testosterone in society. Testosterone is the hormone responsible for aggression in both men and women. One study found that increasing the levels of testosterone in the male brain led to increased reactivity of the hypothalamus, amygdala, and periaqueductal grey when confronted with angry facial expressions. The result: a higher aggression and threat-processing response. In the same test, MRI imaging revealed that men with lower testosterone levels responded less aggressively to the same stimuli. We've all heard people talking about what would happen if women ruled the world, how there would be less violence and wars. Perhaps there is some truth to that! After all, women tend to have lower testosterone levels, meaning less reaction when confronted with anger or negative emotions that would trigger a threat-response or aggressive reaction in men. This isn't a dig against men—after all, I'm definitely fully in the "man" category of my species. But I find it an interesting look at the way our biochemistry could work against us. As men, we have a natural reaction to respond to hostility with hostility. When we perceive someone or something as a threat, our instinct is to get aggressive and "deal with it". Time to stop and realize that it's just our brains triggering that response! Once we realize that our instinctive reaction is biological instead of something that is actually thought through and analyzed, it may help us take a step back to avoid the hostility or confrontation. We could all afford to dial back the aggression a bit, so understanding the way our brains trigger this reaction gives us the power to say, "No, this is not how I actually feel, so I'm not going to react this way." Combat and aggression averted!