Why do Humans Kill?
Thou shalt not kill...
Konrad Zacharias Lorenz (1903-1989) was an Austrian zoologist and ethologist (studies animal behavior). Lorenz proposed in On Aggression (1966) that human beings, like animals, have instincts. Instincts are inherited (not learned). He demonstrated this in animals: a bird raised in isolation from other birds will still try to fly south in the fall. Among the instincts Lorenz found in humans was the aggressive instinct. This means that humans, when challenged, will react with anger and stand to fight. Evidence for this comes from physiological changes that happen when one becomes angry (pulse rate, blood pressure, etc.). These changes are similar in humans and animals.
Lorenz further argued that this aggressive instinct is the product of evolution. Traits that survive do so because they are "functional"; that is, they enhance the ability of organisms possessing them to live. In the case of the aggressive instinct, it serves three functions:
(1) Aggression manifests itself more strongly in the center of an animal's home territory and grows weaker when it moves away from that center.
(2) Aggression makes it more likely that the strongest members of the species will survive and reproduce.
(3) Aggression gives parents the ability to protect their offspring while they are still young and helpless. If animals always ran away instead of fighting, they would desert their young whenever danger threatened.
Wolves vs. Rabbits
Lorenz distinguished two kinds of mammals: those that are not physically dangerous to each other (rabbits) and those that, due to their fangs and claws, are physically dangerous to each other (wolves).
Rabbits display as much aggression as wolves, but there is no danger that fighting will have fatal consequences (unless these are the rabbits from Monty Python and the Holy Grail - does anyone get that reference?).
A rabbit's natural defense is to run away. In fights between rabbits, the weaker one always flees. However, if rabbits are confined in an unnatural way (cage) and fight, they will tear each other to pieces... despite lacking the fangs and claws as seen with wolves.
When wolves fight, the possibility of fatalities is there, yet they rarely occur. Wolves show aggression but do not kill each other any more often than rabbits do. The reason, according to Lorenz, is that along with its aggressive instinct the wolf has evolved an inhibiting mechanism that checks the aggressive instinct at the crucial "kill" moment. The inhibiting mechanism is triggered by the "appeasement gesture" in which the losing wolf turns over on its back, exposing its throat, and accepts an inferior status. By doing this, it saves its life. If the wolf does not do this, then it may be killed.
Humans, Lorenz finds, belong in the category of animals that are harmless to each other. Human being's natural equipment of short, blunt teeth and stubby, brittle fingernails keeps them from being dangerous to each other. Thus, humans have NOT evolved the inhibiting instinct because it was not necessary. To supplement this lack of natural defenses, humans made weapons. Thus, the progression from sharp rocks to firearms was extraordinarily short. Humans are now far more dangerous to each other than wolves are to each other... but they lack the inhibiting mechanism.
The willingness of humans to kill members of its own species must be considered a cause of war, in the sense that it permits wars to happen. If people could change this characteristic of human nature, they could, in theory, eliminate war. (Yeeeeah. Good luck with that...)
Konrad Lorenz joined the Nazi Party in 1938 and was recruited into the German Army as a medic in 1941. He was captured by the Russians in 1942 and remained a POW until 1948. He later apologized for his time with Nazism.
In 1973, Lorenz was awarded the Nobel Prize in Physiology and Medicine for his work in establishing the science of ethology and for his studies concerning behavior patterns in fish and greylag geese.
Lorenz found that auditory and visual stimuli from an animal's parents are needed to induce the young to follow the parents, but that any object could elicit the same response by exhibiting the same stimuli. He called this imprinting and proved it by getting baby geese to imprint the stimuli of "mother" on his wading boots.
The problem is not aggression. After all, wolves fight, too. The problem is that humans fight to the death. They intentionally kill members of their own species whereas wolves do
As victors, humans can (and do) kill helpless victims. As losers, they can (and do) choose to not give up.
Human beings can die for abstract causes, whereas wolves would never fight a Battle of the Alamo.
Chimpanzees will kill other chimpanzees, and gorillas will kill other gorillas. Yet, these primates are the "more advanced animals" and are closely related to humans. Thus, they must not have developed inhibiting mechanisms either.