Aggressive tendencies
Once Spock was quoted as saying the more harsh the planet, life evolved on the harsher the culture, and its people will be. Few places typify this more then Qn'onS. As we saw Qn'onS is extreme in its harshness, as a result, the dominate species would need to develop an aggressive nature that was always alert, aware of its surroundings.
To ensure this the Klingon developed a substance called Qul'Iw, a hormone chemically similar to Human testosterone. Both males and females have this in large quantities. Their brains have large areas devoted to receptors to identify and process this once detected in the blood stream.
A number of things can trigger the release of large amounts of Qul'lw, causing or triggering aggressive behavior. Some of the triggers are, threat of physical danger, sexual arousal, the visual image of a predatory animal, failure to succeed at a task, sensory experiences of combat, or close proximity to another Klingon producing the hormone.
In order survive the Klingon needed to learn how to channel or control the response to this release. Thus in the beginning becoming a better hunter, swifter runner, more calculating in the pursuit of his prey. The effects of Qul'Iw last a long time in the brain, making them slow to forgive or overlook slights. At times never reaching the point of forgiveness or overlooking a slight.
Presence of the hormone in the brain not only sharpens reflexes, ramps up the veK'tal response, and shuts off pain receptors; it increases by 13.9% the brain's ability to reason and process sensory input. Thus a Klingon mathematician benefits as greatly from a surge of Qul'Iw as a warrior would, provided he's sufficiently angry and frustrated.
Early on Klingons saw the benefits to mastering a control over this response. The more efficiently he could control this, the better hunter he became allowing him greater access to the protein rich animals, better mates, more control over the land. Allowing them to become tribal leaders, and its benefits. The weak were fed poorly, if at all, and died off, their inferior genes dying with them. Aggression meant survival. To suggest to a Klingon that he'd do better without it would be like telling Humans to abandon their ingenuity.
Things which can cause a Qul'wl response
Their are certain behaviors that will trigger this response and its a good idea to know what they are.
1) Whispering a Klingon does not whisper in public whispering leads to concerns that one is insulting another one nearby, or repeating things best left unsaid.
2) Avoiding eye contact. Only one who lacks honor, or lies will avoid eye contact to make sure they are not discovered.
3) Eavesdropping to a Klingon this is more then merely being rude it means you are invading personal and private matters that do not concern you.
4) Spying on someone Again this is seen as lacking honor and invasion on matters you have no place being in
5) Expressions and behaviors that are associated with weakness.
As a Klingon it is best that you speak your mind, with strength behind your words. Straight forward and to the point. A Klingon walks a tightrope between boldness and discretion, choosing words carefully but speaking without hesitation.
In an aggressive society where arguments can easily lead to fights, phrasing an opinion correctly increases the chance of survival. While Klingons do not shirk from battle, it is important that not every disagreement or divergence of opinion lead to bloodshed. Klingons hone their skills at rhetoric, to stay out of pointless fights. Like other species, Klingons treat honesty as a cardinal virtue and seldom lie. Rather, they leave thoughts unspoken.
