Parent-offspring conflict must be understood as a mechanism for reaching an optimum equilibrium between short-term (children) and long-term(parents) strategies within an extended family, where the family work as a multilevel unit of selection that remain as a subject of evolution across generations. This wider reformulation explains in detail the unexplained alimentary habits in children. This hypothesis has profound educational implications, since parent investment in repression of children and teenage behaviour is not only non-counterproductive but a necessary and unavoidable part of education of a non-sociopathic personality.
Why children like to eat sugars and carbohydrates while the parents have a hard time trying to make their children to eat the stick or some vegetables?. Why the teenagers fall in love with couples that are not good for them, while parents usually prefer, as couples for their sons, not so good looking but economically solvent, tender boys and girls ?
Donald Symons in "The evolution of human sexuality " gives a explanation of the second: the young people are so passionate because, in the evolutionary past, up to a few generations ago, they had their parents to moderate them. The sons will try to have dangerous adventures, that will increase the number or the quality of their offspring, while the parents will try to maintain them in stable long term relationship that will benefit the extended family as a whole. It seems that both roles have been exaggerated away of the point of equilibrium, since it seems absurd that youngsters are benefitted by their uneducated behaviours and parents are not benefitted by conformists youngsters without self initiative.
In terms of genetic interests according with the Trivers theory of parent-offspring conflict, it does make some evolutionary sense:
In the study of the parent-offspring relationships , Trivers reason about the conflict that appears because 50% of the genes are deferment between each child and each one of his parents. Trivers successfully explain, trough this conflict, the different behaviour of the parent with his brothers in contrast with the disinterest of their childrens for their uncles. Brothers share 50% of the genes, while nephews share only 25% with their uncles. The adolescent revolt can also be understood according with this theory. Upon coming on age, the reproductive interests of male children and their parents diverge. The parents will try to force the son to spend more time helping his brothers, while is in the interests of the adolescent to look for potential mates to have his own offspring. he can potentially have more children than brothers, while females, since they have long pregnancies, can not, at least until their parents are old.
Another example of parent-offsprint conflict is the gestational diabetes. It is caused by the fetus, that try to extract as much resources from the mother´s blood as possible. The genes that generate this hormonal attack are inherited from the father.
According with the parent-offspring conflict theory, the parents could be more interested in stable relations of their sons with other sons of good families. This end up in the benefit of the brothers. That is in the direct interest of the fathers. But the sons also are benefitted by this policy when applied to his brothers. But the parents may also benefit from the increase of fitness of their sons when they increase his own fitness trough risky behaviour. At last, more and better offspring for the sons means more grandchildren for the fathers. There is no reason for such acute specialisation in the context of the parent offspring conflict. The alimentary behaviour of children could be a case of parent-offspring conflict of strategies. But, unlike in the case of risky teenager sexual behaviour there is no apparent benefit for a child or adolescent in eating a disproportionate amount of sugars and carbohidrates. Not in a normal environment. What is missing here?
I will show that the dynamic of this equilibrium is adaptive for the success of all the familly individuals, and thus, it may be considered an internal mechanism for achieving an optimal reproductive strategy within the family. It is a collaboration via conflict. In algorithmic terms, I will give some hints to view this conflict as a computation for a maximization of the family success carried out with the minimum level of information and computational resources.This approach , unlike the Trivers theory of parent-offspring conflict, or the Symons theory of moderation, permits to explain also the nutritional behaviour of children
The missing part in the explanation can be in a wider mechanism that end up in a economic computation for the optimal strategy that is good in the long term for the family as a whole; The generations of a family, must respond to different environments. To respond optimally to each of these circumstances the developmental program encoded in the genetic pool of the family, that include the brain development, must accept a continuum of strategies. In situation of scarcity and uncertainty, short term strategies of survival and reproduction are needed, while in conditions of relative abundance, long term strategies are more successful. The critical elements of the family are the offspring, that are much more prone to die in stressful situations. It is simpler and easier in evolutionary terms that the children to carry a innate short term strategy by default. In case of scarcity, lack of attention, death of the parents etc, they will have not the educative effect of his parent towards long term strategies. In extreme cases, the children can survive and reproduce with their default short term strategies (1)
The taste for sugar and carbohidrates in the childhood is a very short term strategy. these aliments give instant energy. In the other side, to eat proteins and vegetables is a long term strategy because they are structural food for growth, so their benefits are delayed. The same happens with mate choice : a good looking couple guaranty the conception of children with the best genes he can afford, without regard for the long term problems of child rearing alone. In the other side, a couple with a probable longer commitment and resources can help in the rearing of offspring, but this is harder to find or maybe impossible in an ambient of uncertainty.
When parents have resources and time to educate their children, usually they repress the short term strategies and reorient them towards more long term ones. So the confrontation of parent long-term biased education and the children innate short term orientation is a simple mechanism for obtaining the optimum equilibrium in each environment. at the same time, both strategies are simple. No one of both sides need a complicated evaluation of the environment. is the conflict between both strategies of parents and children the mechanism that reach a optimum.
Then the decisive parameter in the personality if the future adult lies in the time and effort of the parents into the repression of the short term strategies. In environments where the parents have to work hard and/or they have no time for the children, the children will have a short term oriented personality, with drug abuse, alcoholism, early sex, gang affiliation, little support for delayed gratification, abandonment of studies etc.
This has no correlation with the socio economic level. Children of rich and poor people will be antisocial if their parents, or some other adults, don´t invest time in repressing their short term strategies.. Just the dedication of the adults to the children is the crucial parameter. Therefore, the modern liberal self indulgent "leave it alone" model of education is also catastrophic for the personality of the children. This is in accordance with what is observed by psychologists today.
The smile of the parents when his son exhibit his short term strategies despite their own repression, for example, when the child lies while playing, shows how this game of equilibrium is pleasant for the parents because the equilibrium is understood as such. The same good appreciation of the conflict appears in the children when he feel frustrated but later satisfied when he complete his homework because his parents demanded it to do so.
Published for the first time here:
(1) Here the family must be understood as a subject of evolution, under the multilevel-selection theory, that is a superset of the neodarwinian syntesis. According with multilevel selection, natural selection operates simultaneously at many sub-individual and super-individual levels. There is natural selection among the molecules, genes, organulles, cells and tissues of an individual, and there is selection among famillies, companies in the market, sport clubs, scientist in research, and societies in collaboration and conflict among them. Competition in a level becomes collaboration at a superior level that make use of the products of this competition if the deletereous (bad) conflicts are supressed and the creative competition is permitted. Since an unit of selection has inside smallers units in competition, it need a mechanism of deletereous internal conflict supression. It would be long to demonstrate that the clans where the humans evolved were a good candidates for being units of selection, since we are talking about a discipline that is just developping now. This is my contribution. super-individual selection under multilevel selection is studied and explained by the new group-selection theory.