We the humans...

Marriage as a social institution has always been a puzzle for me. Why do people marry? And if at all they do why do they end up in such mess, out of self initiative? All this lead me to do some soul searching on marriage.
Primarily from the Darwinian theory we know that there are only two primary instincts in man, like any other animal:
To survive
To reproduce
At the physical dimension, these are the only two prime moving factors for humans, like any other animal. The strive for survival is interesting in humans. It revolves around roti,kapda and makaan.I call this strive to be interesting because no other species of animal die out of hunger in the jungle, except for man in this non-jungle civilized world! Isn't it an amazing fact? No tree dies out of hunger thirst? Even it gets nourishment at its own place without doing any movement of limb(?). But man, "the most important, intelligent" creation dies out of hunger? Is it not a shame for the aadam zaat that 25 000 people are dying of hunger and poverty every day?

Well that is topic for another time. Lets move onto the second point of reproduction. Every specie has this inborn instinct to keep itself alive through future generations, a process called reproduction. And in most species of animals and insects it is the male which is very aggressive and takes the lead in the sexual activity. All the male of most species are polygamous by nature i.e they copulate with multiple mates.
This should have been the case with humans too. In the distant past in the early versions(? IT man) of human race, men should have copulated with multiple females. Then came the rules and customs for this. Rules like people within the same tribe, family should not copulate as by experience they came to know that this leads to weaker new generation. See . But it was also evident the stronger male, say like the leader of the tribe, had higher chances of taking away all the mates and leaving none for the others. This might have forced the society to bring up the idea of Monogamy and hence the insititution of marriage.
So marriage in this civilized world is an euphemism for the second basic instinct. Then over the years with strong religious and cultural programming many things came to be associated with marriage. Then marriages started to be made in heaven!
So by now we conclude that man is internally at the core an animal.
But there are also other dimensions for humans. In spite of being an animal it has somethings which are very unique and very different than other animals. No am not talking about physical differences like ability of grip and bigger brain. But the ability to think, ability to emote!
Yes it certainly sets human apart from the animals. With his thought process, his emotions he has sharpened his survival instincts. It is not for no reasons that man can be found in any and every part of the earth where there is no other species, like in Antarctica there are scientists who have spent 20 odd years!
But another question is do we really think? Or is it that only few think and others follow the herd? Some set the trend others follow the beaten path? Some venture ahead with the torch in hand and others grope in dark?