Probably the main issue on which most thinkers have stumbled upon is why is man able to accept a certain level of slavery ... implying, to be honest with oneself, slavery itself. If you are free, you are not even for a little while or the smallest thing slave of anyone. Etienne de la Boetie rised the question in 1549 and although himself and many others since have had some explanations, the real lever behind such an abnormal behaviour has never been found.
To begin in the right direction, one has to take into account two things.
First, humans are far from being perfect and ready to die if put in a cage as will do most 'wild' animals. Humans are far from the animals but in a reverse Darwin's evolution arrow.
I mean, a cat has been a cat since ... and any cat has no intent to become a better cat. Is it because he is of an 'inferior' species that has no intelligence to find ways to 'progress' ?
Or is it because as a cat, he is a perfect cat, 100% happy to be a cat, even not the smartest or the most beautiful, he is no less or no more a cat than other cats, being a cat is in itself an aim that every cat is granted with.
That does not mean that each cat does not become a 'better' cat ! The kitten learns to be an adult and the adult learns from his life just like a child and an adult human. Humans, on the contrary, spend all their lives searching for their identity. Humans explore in a life time many theories, many practices that might help him to understand who he is, in a word, man feels that he is not 'perfect', or at least, that the human's world he lives in and that he himself has set in motion is far from being an Eden ...
It then could be said that humans are trying the situation in which the cat is 'naturally'. Humans are trying to reach their 'natural balance' and it looks like it is not an easy and short task !!!
Second, and this may already give an answer to the first part, man is, contrary to what he thinks, nearer from animals because, like animals are, man before all is cautious.
He will try to ensure, for women the perpetuation of the race, ie. find for the well being of her children to come the better environment possible, for men, the best way to gain power over his pairs in order to get the best life he can afford to, beginning with women.
These similar aims in their essence are the driven forces of humanity, and since no man can be safe without making an alliance with others, and when men form groups, because there is a need for a leader, there is a place for all the tricks to join the higher ranks of the leading ones, including becoming a slave for some part of oneself in exchange for power and security.
So, despite his claim of unabated progress, man has remained very 'primitive', not like a 'perfect in its kind' animal but like an imperfect as a species human, and his moral behaviour, globally as well as locally (until how he raises his children and how he acts in his family) is quite simple and morally stretchable ... And, not unlike animals, man, from his very beginning, wants to ensure his sustainability as he is, and his first motivation in progress is not progress in itself, but progress as a mean to remain what he is, a species that has many defects in which he prefers to remain rather than become better, and put behind his desire of dominance. If man has progressed also in his moral standards, it is more as a byproduct of his quest to dominance than a progress in itself.
All those things have been studied by, for instance, the Konrad Lorenz Institute for Evolution and Cognitive Research and other private and national offices, agencies and high level 'ethologists', and if ethology was in the beginning the study of animal behaviour, it has been applied to mankind since sometime now, with the terrible effect on the peoples we can see today (The International Society for Human Ethology/ aims at promoting ethological perspectives in the scientific study of humans worldwide). The leading people, who join in leading groups, always favorise the growth of multiple illusory theories and the acceptance by humans of their limitations, and of the deviances that follow, as normal and even desirable.
Individually as well as collectively, man sees his illusions over who he is, and over who he might be able to be, should he decide to overcome those for good, as a protective shield against a situation in which he could not lie to himself because, as a horse with blinders, he prefers to believe wrongly in false theories and advance into dead ends rather than accepting that he can pass over the limitations he himself sets, limitations that ensure him not to lose his 'right to run for domination', his taste of having the most he can get for himself in a life time of pleasure and power.
If Anne Dambricourt* is right in her thesis of an evolution process that does qualitative jumps (please notice I do not subscribe to creationism), still unexplained, and, as in Plato's cave, evolution creates only new shapes of life that were designed in advance. This thesis accounts for the stability of the 'non evolving' animal world, AND man's world who, as an imperfect creature he is, runs after his imperfection and his relative unbalanced way of being as a warranty against the unknown result of his possible own change !!
Any hope ever to see ... a "CHANGE WE BELIEVE IN" ???
* Philipp V. Tobias, director of the unit of Paleoanthropology, University of Johannesburg:
" She has made liberal use of ontogenetic developmental principals and I believe this is terribly important, at a time when very few people are pursuing such an approach. The way in which gene mutations alter the rates of developmental processes provides a valid biological support base for the approach of Dambricourt-Malassé. The work of Dambricourt-Malassé is a healthy corrective and I believe her work should be given every encouragement. Its scientific rigour is not in doubt. I have great admiration for what you are doing and feel that the ontogenetic approach to morphology and phylogeny is the utmost importance, as exemplified by my use of it in my own researches, by the work of Stephen Hay Gould etc."