What can be learned from chimpanzees about human aggression

Human history describes an endless series of wars and acts of aggression. The popular claim is that the origins of murder lie in "human nature", which was formed during evolution from a carnivorous animal. Is aggression natural? necessary? unavoidable? Research in our relatives - the bonobo monkeys - offers more complex answers

Avi Arbel

From the moment Charles Darwin presented the scroll of human roots and made it clear that man is an animal like all animals, the science of zoology became a central field in the way of understanding human behavior and human societies. The recognition that the monkey is the closest animal to man has focused efforts in the study of primates. In the 19th and 20th centuries, researchers devoted considerable effort to observing and monitoring the behavior of monkeys in an attempt to learn as much as possible about our own behavior.

Good, bad, or flat board are three accepted options for defining human nature. Philosophers of nature split into three camps. Their basic premise of human nature formed the basis of diametrically opposed social, political, economic and policy theories.

Today, when the relevant question is whether a concept such as "human nature" even exists, the controversy has lost its strength. In the past, the answer separated the great philosophers. The human heart was created good from his youth, stated Jean-Jacques Rousseau and developed from this claim a desirable model of human society. Rousseau saw man as a noble savage who is influenced by external forces, and if we manage to block their corrupting influence, we will create an idyllic and just human society.

The English philosopher, Thomas Hobbes, represents the opposite view. Humans by nature strive to achieve satisfaction and have no moral inhibitions on the way to achieving their goals. Human nature is bad from his youth, people fight and kill to survive, aggressive just like the prey animals that survive in the wild.

Just like monkeys

Modern animal research, especially observations of monkeys, was used by all schools of thought in an attempt to confirm their claims about human nature. The behavior of monkeys can shed light on critical questions such as - whether aggression and evil are necessary in living beings in general and in humans in particular. Is morality a human act or a genetic evolutionary trait that exists in nature.

The study focused on the Primates series, which includes about 250 species of monkeys and apes. Zoologists consider them to be the most developed of mammals, and accordingly Carl Linna gave them the name primates, meaning the first on top. The human family (Hominidae) which includes, on the human side, the gorilla, the common chimpanzee and the pygmy chimpanzee (bonobo) is also included in the series of primates and it turns out that there are many similarities between man and the other primates, especially the great apes.

The observations indicated closeness in many different levels of behavior. Just like us, the apes work in groups, driven by sexual urges, desire for power and struggles for control. Surprisingly, it turned out that even in the aspects of closeness, empathy and mutual help, we share many common behaviors with the monkeys.

The dramatic difference between humans and primates is brain size. A human brain has an average weight of about 1,400 grams compared to only about 400 grams in its ape relatives. This one kilo makes all the difference.

Man learned to cultivate the land and produce food from it, harnessed nature to his needs and extracted from it energy and other resources used for his well-being. Man domesticated plants and animals and produced food and other consumer products from them, man invented science and technology and with their help broke into the universe and deciphered the genome and the basics of life. He fights diseases, creates works of culture and art and constantly tries to improve his world.

But man is also the most aggressive of the primates, a real murderous predator. The combination between an aggressive nature and an intelligent mind has made us the most dangerous living creatures - man is the only animal capable of destroying the entire planet.

The most intriguing and important question has always been whether this aggression is necessary or avoided? Is aggression an instinct or a trait that is within us and directs our behavior as with any animal, or are there non-aggressive models of ape behavior in nature.

A chimpanzee killing a chimpanzee?

The wise man is a relative of the common chimpanzee. They share 88.5 percent of their DNA and it is accepted by most researchers that man evolved from the chimpanzee. Research between the different groups of members of the chimpanzee family can therefore also shed light on human behavior. The researchers concentrated on these groups, and especially on two polar species in their behavior.

The first species is the common chimpanzee (Pan troglodytes), the murderous monkey among the monkey species. He is not content with killing antelopes and monkey species and eating their meat. Common chimpanzees have been observed killing other chimpanzees of their species belonging to other chimpanzee tribes.

Science knows of chimpanzees who have killed weak individuals, mainly young people in their tribe, but in recent years groups of male killers have also been observed among the chimpanzees, who carry out violent patrols and systematically eliminate males from other tribes. Does the behavior of chimpanzees indicate the origin of human aggression?

Gay chimpanzees?

And maybe we are closer to bonobos? This monkey, also called pygmy chimpanzee (Pan paniscus), lives in Africa and is in danger of extinction. The bonobo, discovered only in 1929, is remarkably similar to humans. The bonobos are refined, relatively upright and have a high forehead. In the past, the bonobo was considered a subspecies of the aggressive common chimpanzee, but today it is considered a species in its own right.

The pygmy chimpanzees studied in recent years in zoos and in the wild are smaller and more refined than their common chimpanzee relatives. At the DNA level they are as close to humans as the common chimpanzee, but in their behavior they are completely different from him.

Dwarf chimpanzees (bonobo chimpanzees) are vegetarians and have never been observed hunting other animals. Encounters in the wild between pygmy chimpanzee tribes are rare, and not many of them have been observed. In those observed cases, no violence of any kind was used. Within the tribe of pygmy chimpanzees there is an admirable bond of brotherhood and friendship. If among the existing chimpanzees conflicts arise that manifest themselves aggressively, mainly in beatings and bites - then all social and personal conflicts among the bonobo chimpanzees are resolved through diverse sexual contacts.

Sexual activity is not limited to resolving conflicts and disputes, nor is it limited to intersexual activity. Bonobo chimpanzees have heterosexual, homosexual and even adult-young relationships. The sexual relationship is certainly versatile and also multiple. Bonobo chimpanzees have been observed in zoos having sex six times a day or more. The pygmy chimpanzees seem to have adopted the motto "Make love no war!" And they realize it in a way that inspires amazement and even envy!

Vegetarianism or meat eating?

Two important researchers, Konrad Lorenz, winner of the Nobel Prize for Physiology and Medicine in 1973, in his book on aggression ("seemingly evil" in its Hebrew translation) and Robert Ardrey, an American anthropologist in his book "The Territorial Command", claim that man developed on the aggressive and murderous path mainly due to his occupation of hunting and eating meat.

The common chimpanzee is a meat eater by nature, while the gentle bonobo is a vegetarian. Is eating meat the key to understanding aggression in animals? Could it be that from the moment you need to kill animals to exist, the evolution of violent and aggressive traits begins?

The hunter and meat-eating theory is controversial and I do not wish to expand here on the many reasons presented to contradict it. The debate surrounding the question of whether "the nature of the human heart is evil from its youth" seems unsolvable when we examine the two poles of our relatives - the common chimpanzee (aggressive and violent) on the one hand, and the bonobo (calm and pacifist) on the other. Can the person belong to only one of the groups? Is it necessary that we take the aggressive path, or is the peace option open to us?

Altruistic monkeys

The Dutch primatologist, Frans de Waal, believes that this option exists and more. According to him, monkeys, just like humans, have moral behavior, mutual help and altruism - a fact that proves that we are not necessarily destined to walk the aggressive path.

De Waal represents this approach in his book, "good by nature". He describes "moral" behavior that he has observed many times, especially in monkeys. These days, his excellent book, "The Monkey Within" (Keter Publishing), has been translated into Hebrew, in which the author tries to compare the behavior of man with the behavior of his relatives from both poles - the common chimpanzee and the bonobo. Through this comparison, de Waal tries to answer the first question we posed: Is human nature bad from youth and is aggression inevitable?

De Waal describes in his book an event that took place in the bonobo cell at a zoo in England. A starling entered the cage, ran into the glass wall and fell to the bottom. The female bonobo approached him, stood him up, tried to get him on his feet and recover him. After he got a little stronger, she climbed the top of the tree with him, carefully spread his wings and tried to release him in the air. The starling fell again and she stayed by his side for many hours until he was able to fly again. Empathy, De Waal calls the trait exhibited by the bonobo box, and it is certainly typical of its kind.

Another characteristic of the bonobo monkeys is the dominance of the females in the group, in contrast to the common chimpanzee tribe where the males dominate. The bonobo proves to us that there is not just one model for social behavior and that in nature, in the group of apes closest to man, there is a system of social behavior that is completely different from what was expected and the initial opinion of researchers, especially those who concentrated on the study of the common chimpanzee.

According to de Waal, we are bipolar creatures and there is no single answer to the question of who we are more like. Man received aggression and murder from the common chimpanzee and even included them with the help of culture and technology. With the help of his mind, he invented ideological explanations to justify his devious behavior, which orchestrate the aggression and murderous violence we inherited from our common chimpanzee relatives.

But in man, as in the bonobo, the qualities of partnership, empathy, moral behavior and cooperation exist and are revealed. It is true that these are largely canceled out in the face of the acts of war and killing, but they exist, can be cultivated and are certainly capable of leading humanity to an optimistic path.

De Waal presents us with a promising thesis. Both options exist and the choice remains up to the person. Human reason allows us an act of choice and not an inevitable drag after "aggressive nature".

Just as we have chosen ideologies that instill aggression and murder, establish the dominance of males and generally see sexual relations as an immoral act, so we can renounce aggression and murder and choose social partnership, helping others, resolving conflicts through sexual relations (by the way, common chimpanzees also do this) and stopping violence towards Members of our species and towards other species.

On the same topic on the science website:

• The roots of religion in chimpanzees
• Years years of the same species
• Facial expressions - a 6 million year old feature

Dr. Avi Arbel is a zoologist and primatologist, a senior lecturer at the Tel Aviv Kibbutzim Seminary College