Adolf Heschl

The evolutionary origin of human hyper-cooperation

Proactive, that is, unsolicited, prosociality is a key component of our hyper-cooperation, which in turn has enabled the emergence of various uniquely human traits, including complex cognition, morality and cumulative culture and technology. However, the evolutionary foundation of the human prosocial sentiment remains poorly understood, largely because primate data from numerous, often incommensurable testing paradigms do not provide an adequate basis for formal tests of the various functional hypotheses. We therefore present the results of standardized prosociality experiments in 24 groups of 15 primate species, including humans. Extensive allomaternal care is by far the best predictor of interspecific variation in proactive prosociality. Proactive prosocial motivations therefore systematically arise whenever selection favours the evolution of cooperative breeding. Because the human data fit this general primate pattern, the adoption of cooperative breeding by our hominin ancestors also provides the most parsimonious explanation for the origin of human hyper-cooperation.

Geometrical gaze following in common marmosets (Callithrix jacchus).

A series of experiments investigating the degree of gaze understanding in common marmosets (Callithrix jacchus) is reported. Results show that marmosets follow the gaze of a human experimenter readily and also use the gaze to locate food in a modified version of the object choice task if influences of chance probabilities and prepotent response tendencies are controlled for. In addition, this new version of the task allows the assessment of the accuracy of gaze following. Marmosets precisely extrapolate gaze direction, past distracting objects and from considerable distances, thereby meeting the criteria of so-called geometrical gaze following. The presence of this ability in common marmosets suggests that higher forms of gaze following might be more widely distributed among nonhuman primates than previously thought.

Chance as Necessity

How does evolution actually function? Charles Darwin was the first to recognize that natural selection is the crucial factor in the environment: it is responsible for the fact that the variously endowed organisms, which stand in direct competition with one another, have correspondingly different probabilities of reproductive success. The logical consequence of this is that even relatively minor differences in the biological fitness of organisms lead to numerical changes in the composition of animal populations; these changes can ultimately even lead to the development of new species. The total of all physical and ecological environmental conditions—in the form of natural selection—therefore decides the evolutionary fate of an organism.

The “Wonder” of Language

With this citation, we have reached the position where we should subject the apparently most important reason for accepting the status of man being something special to closer scrutiny. It should be emphasized once more that by special position we do not mean a unique character like our upright gait or our mole-like (Fam. Talpidae) nakedness since, as already mentioned, every species has its own special position. If this were not so, there would be no sense in talking about species. What is meant here is the much more basic question of whether we as humans have the right to boast of being a genuine exception to the known mechanisms of biological evolution. Even the trained physiologist Jared Diamond, from whose book The Third Chimpanzee (1992)—meant is our own species because of its close genetic relationship with the chimpanzee and the bonobo (Diamond suggests to include the last two species into the genus Homo, resulting in the new species Homo troglodytes and Homo paniscus; for the detailed comparative genetics of the group, see Kaessmann,Wiebe, and Paabo 1999)—the citation above was taken, finally capitulated to the mysterious wonder of human language. Exactly“like some other scientists who have speculated about this question” (p. 54), the all-too plausible answer to the con-troversial condition of Homo sapiens occurs to him. It has to be “the anatomical basis for spoken complex language” (p.54), what else, that has made us into the unique creatures which we undoubtedly are. If this were not so, it would not be understandable how we could differentiate ourselves as sufficiently as we would wish from our nearest relatives who, when viewed genetically, are so close to us. Only a 1.6% difference in the gene sequences between us and the two species of chimpanzee (King and Wilson 1975; for a review, see Gibbons 1998) cannot possibly be the essence of the matter, there must be something more significant that not just separates such a unique species as Homo sapiens from the rest of the large family of primates but also from all the other living species. Diamond himself seemed not so fond of this all-too popular interpretation because a few lines later he had doubts about whether the aptitude for real language made such a very great difference between man and his nearest relatives as was generally believed: However, virtually every claim of any animal behavior suggestive of elements of human language is greeted with skepticism by many scientists, convinced of the linguistic gulf separating us from animals. Such skeptics consider it simpler to assume that humans are unique, and that the burden of proof should be borne by anyone who thinks otherwise. Any claim of languagelike elements for animals is considered a more complicated hypothesis, to be dismissed as unnecessary in the absence of positive proof. Yet the alternative hypotheses by which the skeptics instead attempt to explain animal behaviors sometimes strike me as more complicated that the simple and often plausible explanation that humans are not unique (Jared Diamond 1992, p.146/147).

The True Nature of Scientific Discoveries

What is valid for the biological world, i.e., the world of living organisms must also be valid for the scientific world, i.e., the world of scientists, at least as far as they are living beings and not mysterious ghosts. Biology and science in general do not evolve by themselves, rather, if at all, then only those unique persistent and self-made creatures which, for whatever reason, we call intelligent humans. Hence we are well advised to follow Thomas Kuhn’s path-breaking new epistemological approach centered on the single individual and test how far it can bring us in relation to a possibly novel biology of science. As we have learned from purely theoretical considerations, real cognitive progress, which is always simultaneously evolutionary progress and vice versa, can only be achieved by absolutely blind attempts. These are the universally disliked genetic mutations and recombinations which ensure that, with foreseeable regularity, completely new types of individuals can originate. The developing individual himself must remain completely excluded from advances of this kind out of purely selection theoretical reasons linked to the germ line/soma relationship. This means nothing other than that, in the actual context of science, scientists, contrary to their privileged public reputation, do not do what is asked of them daily, namely bring knowledge into the light of day for this insatiably curious humanity. Astonishingly, Thomas Kuhn’s considerations of what we understand by a scientific paradigm come unbelievably close to this purely evolutionary context:

Requiem for a Wonder of Nature

The outcome of our evolutionary considerations of the cleverest of all the apes can be formulated briefly and succinctly: the fictitious wonder of nature the human being is dead or, more realistically, never existed except in our imaginations. The creature Homo sapiens, however, with all its wonderful, and to some extent strange illusions and fictions lives on and is still evolving today exclusively according to the universal principles of the biological evolution of living things which means by the method of random genetic mutation and concurrent natural selection. The special thing about this statement above all is that a critical epistemology and the modern synthetic theory of evolution can support each other in the conceptual corroboration of this diagnosis (Heschl 1993c). The most important contribution to epistemology consists of the insight into the fact that cognitive gain by the human subject in the course of his ontogeny is impossible, since the latter, for inherent systemic reasons—as a rule somatic mutations are disadvantageous (Knippers 1997, p. 232)—must remain excluded from any adaptive changes. In other words, the personal individual development is exactly like the embryonic development or epigenesis (see special issue of Science 293, 1063–1105)—this latter term comes from the developmental theory of C. F. Wolff in 1759, a time when naive minds still imagined homunculi, i.e., small manikins, in the fertilized egg cells—namely a process controlled in smallest detail by the just all-knowing intelligent genome (see Shubin, Tabin and Carrol 1997).

The Indivisible Individual

Living organisms change in the course of many generations due to mutation and selection. To portray this as the “mechanism” of evolution as has been done in the past and how it usually appears in many contemporary biology text books is, strictly speaking, confusing. The term “mechanism”, borrowed from the language of human technology, implies that a product is made from certain materials in the same way as a machine. The results of this process are then called living organisms and represent the provisional products of the manufacturer who, in this case, is evolution. No matter how lucid this metaphorical representation may be, when used uncritically it has proved itself to be just as confusing as most other expressions borrowed from human affairs. Animals are not subject to a superordinate or completely methodical controlling mechanism which allows them to become increasingly better adapted to living on this planet. Animals live, reproduce, change, and, while doing this, experience various destinies—some successful, others less so—and that is the whole story, that is all there is to it. The result is called biological evolution without any special principle or natural law having to be associated with it. Again, caution is advised with regard to old entrenched terms and concepts.

Evolution Has Us in Its Grip

Let us forget scientists again for, as we have just seen, in principle, they are quite normal. Perhaps they have more education or, rather, conceit than the ordinary man in the street, but “the fact that some academics have intellectual flatulence does not mean that all mankind suffers from such flatulence” (Feyerabend 1980, p. 14). We now want to deal with the much more interesting question of how it could possibly come about that Homo sapiens can be defined as that special, but not unnatural primate species in which the cognitive capabilities, namely those which come under the attractive but very controversial description intelligence, have an apparently crucial importance. It is probably beneficial if we recapitulate what we have achieved with our critical considerations of the wonder of nature man and how this new picture can be applied to what we can observe everyday in representatives of Homo sapiens. Undoubtedly, our most important outcome is the concept that human individuals, just like all other multicellular organisms, be they animals or plants, are excluded from any form of real cognitive gain on principle. Each of us learns, i.e., varies and develops his behavior in manifold ways throughout his life but this has nothing to do with real learning which only occurs through evolutionary, that is undirected phylogenetic changes.

Learning: Appearances Are Deceptive

Let us begin our critical stock-taking straight away with that category of behavior that perhaps demonstrates best the embodiment of development and progress concerning cognition. If something is learned, whether by an animal or a person, this formulation alone seems to include a growth in cognition. No other behavior is so strongly associated with cognitive progress as everything that has the slightest thing to do with learning. Classical behavioral research itself has contributed a great deal to this point of view in that it has always emphasized the sharp contrast between innate instincts and learned reactions (Tinbergen 1951). In this way, the one was ultimately defined by exclusion of the other. If a certain behavior could not be incontrovertibly proved to be innate in the course of certain experiments, it was then thought logically to represent an individually acquired ability, i.e., something really new. Experiments with so-called experience deprivation were used to find out if the behavior of an animal was innate or it could only have been acquired by its own individual experience. When a very definite reaction (courting display to the opposite sex, flight behavior with regard to predators, feeding behavior towards the natural food of the species), on first contact with the object which triggers the response, was shown correctly and, above all completely, it was concluded that the animal already possessed the appropriate, probably innate knowledge that enabled it to react in such a way as to increase its chances of survival.

The Central Dogma Reformulated

In this chapter we will occupy ourselves with the central statement of this book, namely the claim that the only thing we can know about the possibilities of advances in cognition must be that, in principle, we cannot know anything about it. It is only logical, some would agree with a saying that sounds as if it came from Socrates (469–399 B.C.): “I know that I know nothing” which they may have heard sometime. However, Socrates’wise saying misses the mark somewhat since, firstly, he claims something paradoxical and, secondly, he does not take the fundamental question of cognitive acquisition into consideration. With regard to the latter, it makes no difference if one maintains that one knows something or knows nothing. Both claims reflect at least some knowledge. This is generally valid for all ontological puzzles of philosophy that are based on the well-tried patterns “there is a reality of something (e.g., soul, intellect, thing per se, etc.)” versus “there is no reality of anything (e.g., soul, intellect, thing per se, etc.)”.