The brain of an individual, previously only responsible for the integrity of its own individual, is given the additional function of enabling contact with the brains of other individuals in intentional communication, thereby circumventing its own limitations.
results in an evolutionary change of function and an evolutionary innovation. The brains of individuals in the social
group form a network, just as PCs make up a network.
And just as a network consisting of many PCs can solve tasks that would overburden the individual PC, a network of many human brains can solve larger tasks than a single brain.
The network is created to circumvent the natural limits of brain growth (hypothesis 11) a second time. It is created before the beginning of mind and culture and is also arranged in front of them as their prerequisite.
Hrdy estimates that cooperative upbringing began
at the beginning of the Pleistocene epoch (about 1.8 million years ago) when the African Homo erectus appeared. The author drew this conclusion from the relatively small difference in size between the sexes compared to the much older Australopithecines.
The male Homo erectus were
only 18 percent larger than the females. This degree of sexual dimorphism is only slightly more pronounced than in modern humans. (p. 384)
plausible interpretation of Blaffer Hrdy would mean that the hominids were
looking after their young together long before Homo sapiens. Therefore, the use
of human communication by the helpers and thus the whole group of Homo sapiens
is very plausible.
van Schaik and Karin Isler also emphasise the importance of the helpers in
caring for the young:
In most mammal species, the mother is on her own during the strenuous gestation and nursing periods, so any help will save the mother energy.
No mammal on Earth has produced young that take longer to mature or depend on the support of so many others than Pleistocene humans.
With the help of alloparents and parents, these offspring – incredibly costly and equipped with large brains – slowly grew up and enough survived to produce a population capable of penetrating into new habitats, raising children there, spreading further, and eventually populating the entire planet.
Nourished not only by their mothers but also by other members of the group, even descendants who were weaned long before they could care for themselves could slowly grow up without suffering hunger.
(German: Sarah Blaffer Hrdy 2010: Mütter und andere, Berlin, p. 377)
of the longer childhood and adolescence, the raising of the young has become
extremely expensive for humans and their forerunners. Sarah Blaffer Hrdy, the originator
of the quote, has dealt with the prolonged course of human life and its
Once the intentional communication and cooperation between the mother and the infant are established in a social group, all individuals go through this phase as infants and all female individuals experience it from the maternal side.
the mothers, as has been observed in various cases, would otherwise be
overwhelmed with the task of raising the children alone, fathers, grandmothers,
older siblings and other relatives also take on the responsibility of looking
after and caring for the offspring.
individuals will also use the new intentional communication they have
experienced and which the infant demands from them when they communicate with
the new form of communication does provide advantages, adolescents and then
later adults will playfully make use of intentional communication and
cooperation. This is how the new form of communication will become established
in the social group.
the mother–child paradigm at the time of postnatal brain growth. The two facts that are missing in Tomasello’s work are mentioned here.
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
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.
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.
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.
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.
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 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.
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.
The helplessness of the human newborn requires a new form of communication. The newborn monkey can communicate through purposeful actions.
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
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.
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”.
philosophical principle is attributed to William von Ockham, a late English
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.
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.
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
large gap in time is further evidence of the temporal disparity between
previous biological and later intellectual and cultural development.
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.
end of brain growth when Homo sapiens appeared
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,
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
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.
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.
has nevertheless found a solution to overcome this first natural limit of brain
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)
explains the consequences of the narrow human birth canal for the growth of the
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.
there was never any doubt as to why the human brain could not continue to grow.
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)
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.
brain was already perfect, why should it keep growing?
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?
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.
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.
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.