Ok, why not.
I've been trying to explain human behaviour in evolutionary terms, on the "science, creation & evolution" part of this forum. To read this in full detail, go to the 'the Morality and evolutionism' thread on that part of the forum.
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There is one thing that all life forms have in common: They all want to reproduce. All plants, all animals, all fungi, they all have one goal in life, and that is to have offspring. There are quite some animals that DIE after or during the sex. Some species of octopus will guard their eggs until they starve to death, and several species of (male) spiders die while fertilising a female, because they are eaten. Their bodies are quite nutricious to the female, and he indirectly helps to raise the kids (by being food for the pregnant female).
All animals have this goal, but what about us? We are a species of animal too. Linnaeus (1707-1778) gave all known animals a latin name (scientific name). He was a creationist, but that is not very surprising: The Theory of Evolution did not yet exist in his time. The name for human is Homo sapiens sapiens and we are a species of animal, just like the rest of the animal kingdom.
We can detect the same urges and instincts in humans as in other animals. We too want to reproduce. Men are fascinated with women (the only reason porn exists) and women are always looking for the perfect man (the only reason boy band exist ).
There is one little problem: If a woman want to have a child, she will be pregnant for 9 months and then she'll be raising the child for another 20 years (give or take a few years). Men on the other hand could impregnate several women on one day if he needed. Men can be less picky when it comes to partners, because he could make several women pregnant.
The goal of life forms is to reproduce. Men could hypothetically make several women pregnant on 1 day. Women have an evolutionary obligation to pick their mate carefully: They'll be carrying the child for 9 months, so she needs to make sure that he doesn't leave her. Women go for quality (in a partner), while men go for quantity: as much women as possible.
Dating is actually nothing more than finding a compromis between quality and quantity. The girl will search for clues that he is a successful candidate and the man will look for reasons why she is better than all the other potential mates.
Evolution needs animals (including us) to reproduce. If no-one did it, life would die out in one generation. (Duh!). So we have an inborn urge to reproduce. The release of hormones during puberty signals that the body is ready to reproduce. We usually postpone reproduction until we have finished our schools. Having a good job will only benefit the new born child, so it is in your best interest to finish your school first.
The urge will start with puberty. The average age of people during the Middle Ages was about 20/30 years old. It was quite necessary to have children when they were young. Our average age is 70/80 years. We can actually PLAN our children. We have however the instinctal urges.
The goal of our genes is to make copies of itself, and the only way to do this is by having a child. Your body 'pushes'' you in the right direction by making you feel attracted to the other sex. You start to look for 'hints' that you are considered a good candidate.
The evolutionary urge to reproduce is quite a strong one. We have some basic urges: Eating, drinking, breathing and going to the bathroom. These are VITAL things.
The urge to reproduce is not VITAL (means you do not die if you don't reproduce), but it is as important as these other things. Eating, drinking etc. are important to keep your body alive, but having sex keeps your SPECIES live. And this is in the end the most important drive, keeping your species (=keeping sets of genes that are almost the same as yours) alive.
Masturbation is a way to releave yourself of this urge. Mentally we are nothing more than primitive hunter-gatherers. We are scared of animals that could hurt us. The instinctal fear of spiders and snakes is an inborn fear that has helped our species survive for millions of years.
We obey to the same instincts as animals, with the exception that we can perform a 'second opinion' on our instinct by using our conscience. Our conscience is nothing more than a cerebreal mechanism to judge instincts. It is quite an interesting ability when you think about it. And it has proved its worth: Prett much every member of our species now has this ability.
Our body does not tell us to 'make babies' it tells you to have an orgasm. The result of man=>woman=>orgasm is usually pregnancy, which is good for evolution (yes, you can die happy now, knowing that copies of your genes will be passed on tho the next generation.)
Apparently, the orgasm is enough to 'fool' you body into 'thinking' it has done its job. You have not produced offspring, but your body interprets ejaculation as "having reached your goal, thus happy happy, joy joy".
Your body will basically try one thing, and that is to get you laid. It will try this with chemical warfare: Hormones are released INSIDE your head and there is nothing you can do about it.
Reaching an organsm (talking to both male and female readers here) will get you a rest from those infernal hormones and you will notice that it actually feels very good. Why anyone would think its a sin, I don't know. It's like saying that enjoying a good meal is a sin. You are just following an instinct, aren't you?
I think that we evolved this ability, others think it was god who gave us these feelings. But if god gave us these feelings, why would he forbid them? That would be quite sadistic. That's like putting a hungry man in a room full of food and telling him that he'll be punished for all eternity if he even thinks about eating the food.
Masturbation is a natural bodily function. We should take an example of our cats and dogs. They are not bothered by pointless feelings of shame that are induced by our social climate. The claim that it is 'morally wrong' doesn't hold either. Morality is a very subjective concept. It means something different for every person.
My personal way of looking at it is that moral behaviour is behaviour that benefits our society. It is a result of being a social animal. As long as our behaviour does not harm society, I don't see anything wrong with it, and it is that yardstick that I use to measure things by.
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