Kann die Evolution die Natur des Menschen erklären?

(c) AP (Paul Thomas)
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Offensichtlich, sagt der Affe. Wissenschaftler im Streitgespräch: Der Psychologe Frans de Waal führt ins Treffen, dass die menschliche Moral auf Empathie und Gegenseitigkeit aufbaut.

Obviously, says the monkey. Human nature simply cannot be understood in isolation from the rest of nature. This evolutionary approach is difficult to accept for many people, but it is likely to generate even more resistance once its implications are fully grasped. After all, the idea that we descend from long-armed, hairy creatures is only half the message of evolutionary theory. The other half is continuity with all other life forms. We are animals, not only in body, but also in mind. This idea may prove harder to swallow.

We are so convinced that humans are the only intelligent form of life on earth that we search for other intelligent beings in distant galaxies. We never seem to run out of claims about what sets us apart either, even though scientific progress forces us to adjust these claims every few years. That is why we do not hear any more, that only humans make tools, imitate each other, have culture, think ahead, are self-aware or adopt another's point of view. It is the claim of human uniqueness that has persisted for more than a decade.


If we look at our species without being dazzled by the technological advances of the last few millennia, we see a creature of flesh and blood with a brain that, albeit three times larger than that of a chimpanzee, does not contain any new parts. Our intellect may be superior, but we have no basic wants or needs that cannot be observed at our close relatives as well. I daily interact with chimpanzees and bonobos, which are known as anthropoids precisely because of their human-like characteristics. Like us, they strive for power, enjoy sex, want security and affection, kill over territory, and value trust and cooperation. Yes, we use cell phones and fly airplanes, but our psychological make-up has remained that of a social primate.

To explain human behavior as a „mere“ product of evolution, however, is often seen as insulting and a threat to morality, as if such a view would absolve us from the obligation of leading virtuous lives. The geneticist Francis Collins sees „moral law“ as a proof that God exists. Contrariwise, I have heard people echo Dostojeweski's Ivan Karamazov, exclaiming: „If there is no God, I am free to rape my neighbour!“

Perhaps it is just me, but I am concerned about anybody whose belief system is the only thing standing between them and their repulsive behavior. Why not assume that our humanity, including the self-control, needed to form a livable society, is fundamentally based in human beings? Does anyone truly believe that our ancestors lacked rules of right and wrong before they had religion? Did they never assist others in need or complain about an unfair share? Human morality must be quite a bit older than religion and civilization. It may, in fact, be older than humanity itself. Other primates live in highly structured cooperative groups in which rules and inhibitions apply and mutual aid daily occurs.


Even without claiming other primates as moral beings, the pillars of morality can easily be recognized in their behavior. These are summed up in our golden rule, which transcends the world's cultures and religions. „Do unto others as you would have them do unto you“ joins empathy (attention to the feelings of others) and reciprocity (if others follow the same rule, you will be treated well, too). Human morality could not exist without empathy and reciprocity, tendencies that have been found in our fellow primates.

After one chimpanzee has been attacked by another, for example, a bystander will go over to gently embrace the victim until he or she stops yelping. The tendency to console is so strong that Nadia Kohts, a Russian scientist who raised a juvenile chimpanzee a century ago, said that when her charge escaped to the roof of the house, there was only one way to get him down. Holding out food would not do the trick; the only way was to sit down and sob, as if she were in pain. The young ape would rush down from the roof to put his arms around her. The empathy of our closest evolutionary relatives exceeds even their desire for bananas.


Reciprocity, on the other hand, is visible when chimpanzees share food specifically with those who have recently groomed them or supported them in power struggles. Sex is often part of the mix. Wild males have been observed to take great risks raiding papaya plantations and then to return to share the delicious fruit with fertile females in exchange for copulation. Chimps know how to strike a deal.

Our primate relatives also exhibit pro-social tendencies and a sense of fairness. In experiments, chimpanzees voluntarily opened a door to provide a companion with access to food, and capuchin monkeys seek rewards for others even if they themselves gain nothing out of it. Perhaps helping others is self-rewarding in the same way that humans feel good when doing good. In other studies, primates will happily perform a task for cucumber slices until they see others being rewarded with grapes, which taste so much better. They become agitated, throw down their measly cucumbers and go on strike. A perfectly fine vegetable has become unpalatable! I think of their reaction whenever I hear criticism of the extravagant bonuses on Wall Street.

These primates show hints of a moral order, and yet most people still prefer to view nature as „red in tooth and claw.“ We never seem to doubt that there is continuity between humans and other animals with respect to negative behavior – when humans maim and kill each other, we instantly call them „animals“ – but we prefer to claim noble traits exclusively for ourselves. When it comes to the study of human nature, this is a losing strategy, however, because it excludes about half of our background. Short of appealing to divine intervention as an explanation, this more attractive half is also the product of evolution, a view now increasingly supported by animal research.

This insight hardly subtracts from human dignity. On the contrary, what could be more dignified than primates who use their natural gifts to build a humane society?

("Die Presse", Print-Ausgabe, 07.06.2009)

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