I therefore propose an alternative scenario:

Rail journey to Lake Titicaca, Peru
Rail journey to Lake Titicaca, Peru

the mother–child paradigm at the time of postnatal brain growth. The two facts that are missing in Tomasello’s work are mentioned here.

1. There is now a proposal for the situation in which the first step was taken: Postnatal brain growth led to the helpless human newborn, which was dependent on cooperation and intentional communication.

The situation was inevitable because it was predetermined by biological evolution, and it was permanent and not unique or accidental because all individuals went through this childlike stage of development. The situation therefore required some form of an evolutionary adjustment.

2. There is now a proposal for the individual who took first step. This was the newborn’s mother, who could only ensure the survival of the child through cooperative actions.

Continue reading “283”


Hypothesis 14

Mother and newborn 2

Funerery Rock, Machu Picchu, Peru
Funerery Rock, Machu Picchu, Peru

The newborn baby cannot develop its own activities; it orients itself towards the mother and tries to anticipate her actions and to share her intentions. This is the origin of the shared intentionality observed only in humans.

Intentional communication and cooperation have their phylogenetic origin in the communication and cooperation of mothers and newborns during the newborns’ helplessness in the first year of life.


The starting point of my considerations here is the study by Michael Tomasello on The Origins of Human Communication (German: Die Ursprünge der menschlichen Kommunikation Frankfurt/M. 2009). His comments on pointing gestures as the beginning of communication are convincing.

As far as the evolutionary beginnings of typically human communication and cooperation are concerned, however, I have come to different conclusions on the basis of theoretical considerations. Tomasello describes the phylogenetic origins in Chapter 5.

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For newborns it is essential for survival,

Temple Mount + Intihuatana, Machu Picchu, Peru
Temple Mount + Intihuatana, Machu Picchu, Peru

if they are not capable of acting themselves, then at least to understand those individuals who can act i.e. first to understand the mother and her actions and then later, if possible, to be able to predict her intentions i.e. to recognise her intentions and to behave in such a way that the desired care behaviour is achieved.

Likewise, mothers learn to interpret the behaviour of their newborn children and to recognise their children’s intentions and wishes. Here is the place where mentalisation first emerged and further levels of intentionality were tested, because they were absolutely necessary for the infant survival.


IV.    The networked brain

Hypothesis 13

Mother and newborn 1

Intihuatana + Temple Mount, Machu Picchu, Peru
Intihuatana + Temple Mount, Machu Picchu, Peru

The helplessness of the human newborn requires a new form of communication. The newborn monkey can communicate through purposeful actions.

The human newborn cannot. Instead, mothers have to guess their newborn’s wishes. They must understand the baby’s intentions in order to be able to provide the appropriate care.


While a newborn monkey is already an active member of its social group, the human newborn is helpless. The phenomena of mentalisation and intentionality are important to understand the mechanisms that work here and the abilities that need to be mastered by individuals.

Dunbar describes it as follows:

Nevertheless, primatologists have always assumed that there is such a thing as “social cognition” (a form of social recognition). This ability manifests itself in people as being able to put themselves in the mind of another person (a phenomenon known in psychological literature as “mentalising”.

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A philosophical principle is attributed to William von Ockham, a late English academic,

Main temple + Intihuatana, Machu Picchu, Peru
Main temple + Intihuatana, Machu Picchu, Peru

since the simplest explanation of a phenomenon is preferable to the more complicated ones. If one fact or argument is true and at the same time sufficient for an explanation, other explanations must be rejected.

In the case of the evolution of the human brain, this means: The biological explanation of the development of the human brain is based on true facts and offers a sufficient explanation. All more complicated explanations based on tool use, language, or other cultural achievements are to be rejected.

When comparing the development of the human body, including that of the brain, on the one hand and human culture on the other, the large gap in time between the appearance of Homo sapiens about 250,000 years ago and the first cultural artefacts with symbols about 60,000 years ago in South Africa needs to be considered.

This large gap in time is further evidence of the temporal disparity between previous biological and later intellectual and cultural development.


Hypothesis 12


Temple Square, Machu Picchu, Peru
Temple Square, Machu Picchu, Peru

The human brain was created on a purely biological basis without the influence of intellectual/cultural forces on the biological evolutionary process and even before the development of human culture.


The brain is a very expensive organ for the organism because it is energy-intensive and prefers to be supplied with energy. Growth up to the size of the human brain, and the end of that growth because of human reproductive biology, can be explained biologically.

This excludes more complicated mental or cultural causes according to the philosophical principle of Ockham’s razor.


The end of brain growth when Homo sapiens appeared

Palace District, Machu Picchu, Peru
Palace District, Machu Picchu, Peru

about 250,000 years ago has nothing to do with the fact that the brain, unlike the earlier hominid brains, would have been perfect (Mayr). I also consider the idea of a seamless transition from genetic adaptation to cultural tradition (Habermas) to be an unacceptable simplification,

one that does not take sufficient account of the change of era at the end of the growth in size of the human brain. Here further intermediate steps, which make this type of development plausible, are mentally necessary and are still to be described.

The prolongation of brain growth into the first year after birth makes the human brain even more expensive and leads to the problem of who can afford the costs.

The mother alone probably cannot afford the increased costs; further helpers are required. If we assume pair bonding and family structures, the father and other family members, such as older siblings, can be considered additional helpers.

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Evolution has nevertheless found a solution to overcome this first natural limit of brain growth.

Palace District, Machu Picchu, Peru
Palace District, Machu Picchu, Peru

Robert D. Martin continues:

It appears that because of the unique size of the adult human brain, part of the growth that would normally occur within the womb has been transferred to postnatal life.

It has been correctly said that human pregnancy actually lasts 21 months: nine months in the mother and another twelve months outside. This particular characteristic related to the development of the human brain explains why our newborns are so helpless, despite the fact that they correspond in many other respects to the standard pattern that nidifugous animals typically reveal. (p. 105)

Martin explains the consequences of the narrow human birth canal for the growth of the newborn’s brain:

A closer look reveals a special reason for the relatively helpless condition of human newborns. It has to do with the growth of the brain. The general rule for primates is that the brain has reached half its adult size at the time of birth.

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But there was never any doubt as to why the human brain could not continue to grow.

"Fountain of Ceremonies", Machu Picchu, Peru
"Fountain of Ceremonies", Machu Picchu, Peru

The answer lies in the biology of human reproduction. Robert D. Martin explains the problem in the essay The Evolution of the Human Body:

The dimension of the birth canal that passes through the pelvis represents a limit to the circumference of a newborn child’s head, and in humans the relevant dimensions are even smaller to enable the pelvis to be remodelled for bipedal walking.

At birth, the size of the human brain has already reached the limit set by the pelvis. The human birth process has therefore become exceptionally complex compared to that of other primates. It includes the continuous twisting and turning that a newborn has to do in order to be born head-first when he or she turns towards the mother’s back.
(Die Evolution des menschlichen Körpers, in: Fischer/ Wiegandt: Evo­lu­tion, pp. 74-109, p. 105)

This is where the development into a human being should have come to an end. The birth channel of the early human woman, who was still far from Homo sapiens and its culture, blocked brain growth and thereby preventing the development of the great ideas of a Descartes, Darwin, Kant and Mayr.


The brain was already perfect, why should it keep growing?

Entrance to the "Mausoleum", Machu Picchu, Peru
Entrance to the "Mausoleum", Machu Picchu, Peru

Is the answer to the question of the end of brain growth really that simple? In the passage already quoted, Jürgen Habermas also overlooks the problem of the end of the growth of the human brain:

Once the growth of the human brain stopped, cultural learning processes began to take the place of genetic adaptation. What other animal species lack is the transfer of symbolically stored knowledge from generation to generation, such that it can be revised and expanded light of new experiences.

If genes cannot induce human adaptation, does culture have to take over? But where does culture come from? Who discovered cultural learning processes?


Hypothesis 11

Extended brain growth

Round Tower, Machu Picchu, Peru
Round Tower, Machu Picchu, Peru

In humans, brain growth is limited by the width of the woman’s birth canal, through which the child must pass at birth. The selective advantage of an individual having a large brain reaches a natural limit here.

To overcome this natural limitation, evolution has found two solutions in human beings: The first solution is to prolong brain growth into the post-natal period. This solution is acquired by a further increase in effort because of the required and time-consuming care of the helpless infant.


Why, during the course of evolution, does the human brain simply stop growing? This question is just as fascinating as the question related to the causes of growth in previous periods. Surprisingly, it does not get discussed very much.

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Another advantage of large social groups is that they are attacked less often by predators.

Palace District, Machu Picchu, Peru
Palace District, Machu Picchu, Peru

Dunbar comments,

that the main reason for the development of large groups of primates is the risk of ending up as prey. This risk of becoming a victim has even contributed directly to the selection of large brains, as it has been shown in many instances that predators attack members of species with small brains with a disproportionate frequency, relative to the frequency in their respective habitats. (p.250)

Dunbar compared the neocortex volume of monkeys and great apes with the sizes of the respective groups and determined the correlation discussed above. Applied to humans, Dunbar comes with a group size for humans of 150 individuals (the Dunbar Number).

He finds this number in many forms of human organisation: in the average size of hunting and gathering clans, in the size of European villages before the industrial revolution, in the size of personal networks, etc.

Obviously, the relationship between brain and social complexity in humans is similar to that of the great apes.

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In primates, the group size correlates with brain size. In other mammals and birds this is not the case.

Machu Picchu, Peru
Machu Picchu, Peru

There, however, it is apparent that the monogamous species (in pairs) have a larger brain than the polygamous species. Dunbar’s interpretation of this finding is,

that the original incentive for the evolution of larger brains can be found in the development of bonding in couples, which usually goes hand in hand with the fact that both parents care for the offspring (…)

We can imagine that in the event that when pair bonding became an established practice, it led to larger brains and the cognitive ability to deal with complex relationships (relations). Primates have succeeded in exploiting these cognitive abilities by generalising them so that they would be available to all members of social groups. (pp. 249s)

So with the larger brain, which was developed through pair bonding, more complex social systems could be mastered with friends i.e. with non-reproductive partners.


The larger the brain, more precisely: the neocortex (historically the youngest part of the cerebral cortex) in a primate species,

Machu Picchu, Peru
Machu Picchu, Peru

the larger the group in which this primate species can live. That implies that the size of the brain depends on the number of social contacts that individuals of this species manage. Dunbar continues:

Furthermore, additional analyses have shown that a number of behavioural patterns that are particularly associated with the social complexity of primates are also correlated with the relative size of the neocortex.

These include the size of the grooming clique (grooming: mutual body and fur care), the use of alternative mating strategies in males, the use of coalitions and alliances, manoeuvring for tactical deception, and the quality of social play. (pp. 247s)


Hypothesis 10

The social brain

Parade, Cusco, Peru, 27. 8. 1989
Parade, Cusco, Peru, 27. 8. 1989

With the brain size of monkeys, the potential size of the social group increases, as individuals with the larger brains can establish and maintain social relationships with a larger number of group members (Robin Dunbar).

The advantage of the larger social group and the advantage of greater contact ability lead to a selection of individuals and groups with the larger brains. Selection promotes brain growth, as confirmed by hominid fossils.


The brain is an expensive organ because it consumes a lot of energy that the living being has to provide. Why did it paid off in evolution to invest in large brains?

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