I see this asked so many times and too seldom is it explained how different the mind of a leftist is from ours. Short answer is that our brains are different, check the brainscans. If you are not sure yet which you are, a scientist scanning your brain could tell you: braindecoder.com
Haven't you ever thought how two highly intelligent and educated men, one a leftist and the other a conservative, can be presented with the same evidence and the same facts yet reach two opposite conclusions? What r/K theory proposes is that political ideology, like much of our behaiviour, is an expression of our survival strategy. First you are presented with facts and presumptions, then your brain (being wired genetically to be either r or K) interprets the facts in a way that makes sense for your biological survival. Depending on the selective pressures in nature (society), either r or K will be more successful, meaning that the successful strategy will be better represented in the future generation. So far r and K selected organisms have been living side by side in several species, humans being one of them.
The prime example here is the wolf. When there are K selective pressures in nature, the species will adopt K-traits. K selective pressures include a limited food supply, harsh punishment (death) for failiure and fierce competition for resources. If a pack of wolves live in an area inhabited by enough prey to feed X amount of wolves then each new cub is above the enviroments carrying capacity. As a wolf mother gives birth to her cub that is number X+1 she has to make sure that this cub is strong enough, smart enough and adaptive enough to outcompete one of the pre-existing wolves in the pack or the cub will starve as soon as it is on its own. In this enviroment some traits give wolves a clear evolutionary advantage. Like, the wolves that seek the best possible mate, monopolize this mates superior genes through monogamy, wait until they are old enough to take care of their offspring and then spend much time with their offspring which matures more slowly (but advances further) give their offspring the best possible advantage to compete in life. If a wolf would screw around and pop out offspring willy-nilly with no thought or rearing, most cubs would not have what it takes to succeed and die off as soon as winter comes, being outcompeted by their stronger more well trained peers. Other K traits include being able to work well in groups, where in-group loyalty increases everyones survival chanses. Hostility to outsiders; if a competing pack encroach on your territory they threaten the entire packs survival as they eat your prey and thus they limit your pack's food availability. If not driven out, your pack will weaken and allow for more encroachments until you die out or leave the territory all together. The life of the K is a struggle to perfection, where the weak must perish so that the strong may survive and advance the species as a whole.
The posterboy animal for the r selected strategy is the rabbit. Think of an unlimited food supply (grass), that could never be eated in all your lifetime and a predation that kills seemingly randomly (hawks, foxes, hunting, etc.) and your life could end tomorrow. The bunnies that are exclusively monogamous miss out on several mating opportunities that leave you outcompeted by your peers that screw anything and everyone. The bunnies that spend too much time rearing their young cannot produce as many batches of younglings as their less caring peers, and what skills could their mother teach them? Running away, mating and eating grass is all they need to know and they've got that in their genes already. A rabbit who fights for territory wastes time and energy and gains nothing. There is always more grass to eat and this rabbit will be outcompeted by its peers who simply will eat and if need be, run away. In such an environment in-group loyalty offers the rabbits no benefits, anyone can survive fine by themselves, and all are preyed upon equally so why stick your neck out for others?