Survival Instincts

You will be surprised to know that most human behaviour and instincitve likes/dislikes (the one's common to almost all people) can be explained on the basis of

Survival and the propagation of one's genes

Well, at least the reasons linking certain behaviour or instincts to the above objective was valid at the time when we were but hunters in the jungle. Somehow after all these years, we haven't yet grown out of a few of them that have become ........."less necessary" shall we say? For example:

Fear of the dark and sudden loud noises:
Our most developed sense is that of sight (relatively). In the dark, a human being is helpless. If something attacks him (a snake or panther), he won't be able to defend himself. So fear of the dark was a nature's way of ensuring man didn't unnecessarily risk his life. Now a predators strike is usually accompanied by a sudden loud noise. So fear boosts man's reflexes/attention and prepares him for flight. Even when man becomes too frightened to move, he becomes harder to see (if camouflaged or in dim light) owing to the fact that moving objects catch the eye better than still ones - which is again a necessity because moving prey and predators are more important than still plants and rocks.

Men desiring beautiful women:
Beauty - especially skin texture, radiance, hair quality, proper weight (neither emaciated nor too much overweight) is a sign of health. A healthy body is necessary to ensure the viablity of offspring.

Women desiring men of power/ men who are caring and understanding:
When mankind lived in tribes, power (think of the tribal chief) brought better promise of safety and food. Today power holds the promise of luxury and social-respect. Men who are caring and understanding have more chances of sticking around when a chlid is born - vital to the future of the child.

Desire for peer approval:
Cavemen who didnt' blend in with the pack weren't welcome. For a pack to stay together solidarity is important. Now members of a pack were mostly an extended family and hence had a lot of common genes. Common genes means common characteristics. That's why instinct made them hostile to outsiders. And that's why today lots of people find it hard to trust other people who are of different ethnicity, religion, colour, language giving rise to communalism.

Parents giving more priority to thier children's needs then thier own, children not reciprocating:
The propagation of life and one's own genes demands that the newer generation be given more preference than the older.

Altruism as a natural calling:
Back in the days when man was part of a pack, the survival of the individual depended on the survival of the whole group. Here, Nobel Laureate John Nash's Game Theory applies: Everyone acting for the common benefit will produce results that are better for everyone than those when each acts for what is best for only his own interests. So if each person on the detection of an enemy (say a predator like a tiger) ran off and alerted the rest instead of running as far as he can from it,this would increase the chances of survival of everyone.

There are more. These are just the ones that come to my mind right now. I'm sure if you try you can think of many more. Please tell me if any occur to you. I hope i've helped you get an insight into the reasons for some of our basic desires, preferences and instincts.