If you examine yer hyumin bean (from a dispassionate viewpoint, in the altogether, as it were,), it’s hard not to reach the obvious conclusion: this is a ridiculous critter. It’s damn near helpless. It’s got no hair or fur (well, almost) to protect it from the elements, and its exposed flesh is soft and easily torn. Its digestive system is too short and simple to exist entirely on plant matter, yet its teeth and fingernails are weak stubs, ‘way too short, dull, and flimsy to slash and rend prey, and it hasn’t got nearly enough fast-twitch muscle to be an effective prey-getter anyway. Its young present an horrific metabolic load to the mother during development — they can easily be a tenth of her mass, they hang around for three-quarters of a year, and during the last third of that they move around. Their heads are so big they can barely manage to get out of the mother, and once they are out they can barely move for a year or more, requiring constant support and causing a continued severe metabolic load. It doesn’t reach sexual maturity for well over a decade, and it gets there too soon — it needs another two or three years, minimum, to be big and strong enough to support reproduction. Intelligent design, hmph. It looks like it was put together by the same people who went on to found Microsoft.
Naiïve believers in evolution might expect it to correct the deficiencies. That hasn’t happened. “Later model” hominids are generally bigger than their predecessors, but they haven’t developed tougher skins, fangs, claws, or more fast-twitch muscle, nor do they have digestive systems better suited to a herbivorous lifestyle — if anything the changes have been in the opposite direction. Certainly the later versions of fetal and child development have been in the direction of greater burden.
What’s happened instead is that we have developed behavioral changes that help us survive, the most important one being leadership. Despite the absolute necessity for survival, human beings don’t work together all that well. Two people can pretty well do twice the work of one, but it isn’t inevitable; three people will almost never do three times the work of one, and larger assemblages get worse, rather than better — unless they have a leader. A leader resolves disputes and directs activities, getting everyone being led working together rather than wasting time on extraneous matters or resolving intragroup conflicts. (There’s a downside to that, to be addressed another time.)
There are two main factors of leadership: becoming the leader (that is, getting the position) and what the leader directs the group to do. One of the things that the leader will always do is use his (it is mostly “his”) influence to gain out-of-proportion access to food and mates, so those behaviors that lead to getting the leadership position are strongly selected for. If the leader directs the group well enough, it will survive and prosper — but it is individuals that eat and mate (or not), and the behaviors that result in good management benefit the whole group, not just the leader; the result is that good management behaviors are less strongly selected for in the leader than the behaviors that result in gaining a leadership position.
There are two ways of becoming a leader: violence and persuasion. A person wanting to become a leader can either beat the others into submission, or convince them that he is better suited to the job. The trouble there is that the first always trumps the second. A big, strong, stupid guy will almost always win over a physically weaker smart one. If he’s really stupid the tribe dies out, so there are selection forces to ameliorate that; they result in the classic “tribal” arrangement, with a big, strong, not terribly stupid chief assisted by henchmen and advisors who are weaker than he is but smarter.
Modern humans haven’t been around all that long, and ultramodern behavioral adaptations like agriculture, cities, and industrialization have existed for a tiny fraction of human existence. Evolution takes time to work, and it hasn’t had time to adapt human behaviors to the new conditions, so the behaviors we exhibit are mostly those we evolved during our days as hunter-gatherer-scavenger tribes. Most importantly, the behaviors necessary to make agriculture, cities, and industrialization work have not been selected for — they are intellectual constructs, not (yet) heritable behaviors, and in a pinch we always revert to heritable behavior patterns. (Quibbles about “instinct” be damned. How does a mother cat “know” to care for her babies? At any rate, behaviors can be and are transmitted by extragenetic means; “heritable” does not necessarily mean “genetic”.)
One of the things about of heritable characteristics is that they are unevenly distributed among the population, with our old friend “The Bell Curve” approximating the distribution. That is, there are a majority with the characteristic to a medium degree, a goodly number that have it more strongly and an equal number with less, and a few extremes who have it very strongly or almost not at all. The ones who have the “desire to be a leader” characteristic very strongly will do almost anything to achieve that status, and experience tells us that there are always a few wackos for which “almost” goes away.
A complex, populous industrial society provides a lot of slots for leaders, especially in Government and private bureaucracies, and every new program introduced provides more. The benefits of gaining such leadership slots are the same as they were for the hunter-gatherer-scavenger (“primitive”) societies that shaped our behavior: more access to food and more opportunities to mate. The behaviors necessary to gaining a leadership position haven’t changed all that much, either, although the proportions may have — it’s harder to achieve a leadership position by beating up others and easier to do so by intellectual means, relative to the conditions in a primitive tribe.
The behaviors necessary to accomplish effective leadership have changed out of all recognition. Many of the behaviors that led to tribal success in the primitive society are detrimental or destructive to an agricultural or industrial one. For example, a primitive tribe that drives another tribe away gains access to more resources, and one that defeats another tribe and incorporates its members (especially females) gains genetic diversity as well as more resources; but an industrial society that conquers another has to destroy the very wealth it wants in order to succeed, and gains only more dependents and expense. That’s not what our inheritance tells us, though.
If we build a social structure that contains power positions, those positions will attract those who have inherited a strong tendency to want a power position. The trouble is, even the behaviors that led to success in a primitive society were subject to weak selection, and the behaviors that lead to success in a modern, complex, industrial society have not been selected for at all. Power positions thus get quickly filled with people who want them badly enough to work hard to get them, but have no idea how to behave for success of the group from that position of power.
Examples will no doubt occur to you.