Why is Pleasure linked to Procreation?

[Apes Anonymous]

Hi everybody, great forum!
I got here after doing a search in google about a question that's been preoccupying me about evolution. I am no scientist as you'll soon guess, but as most people find evolution to be one of the most fascinating subjects.
I know that Evolution experts agree that mutations are the product of pure chance and that although it might look like "mother nature" has a plan to keep us alive that is not the case. Nature, we are told, has no favorites and merely supports the fittest.
This is a hard concept to swallow for the common man who sees that nature, in fact, rewards all our survival instincts, and it sure looks like we are being forced to survive and procreate. We are, for instance, rewarded by pleasure every time we eat, or engage in sexual intercourse , and are punished by pain or fear when our life is threatened.
Now science tells us That it only looks that way because we are mixing cause and effect, and that we should say: "I'm still alive because nature gave me the instinct of fear." and not the other way around: "Nature gave me the instinct of fear in me in order to keep me alive". The second statement is dead wrong because nature doesn't give a damn if we live or die.
I accept the the theory of evolution as a valid explanation for life, but the hard part for me is to understand how so much incentive to procreate can be given to living beings without any intention on the part of nature. For example, how come the sensation of pleasure is concentrated on the genitals? It is hard to keep the cause-effect order in mind if you know what genitals are for. The first thing that comes to mind is that animals are therefore encouraged to procreate.
I think that when people who believe in Intelligent Design it has more to do with the feeling that nature has an intention than what we are told by religion.
I think that maybe if I understood a bit better how Evolution operates, it might clear my confusion, so I guess my question to the knowledgeable members of this forum is: "How can you explain the development of sensations such as pleasure or pain in evolution and what are the mechanisms that associate them to the survival of a species?" I'll be grateful for any links you can point me to.

[Fishteacher73]

Pleasure and pain are basic indicators of of actions and their rewards. Sex, food, etc. are pleasurable because they in general are positive for viable offspring. Pain indicates things that are generally harmful. Granted as we have grown intelectually we have learned to manipulate these reactions to our advantage with either drugs to induce the brain's chemical reaction to pleasure or over-indulge to the point that it is harmful.

[Apes Anonymous]

Hi Fishteacher73,
Yes I understand that pleasure and pain are vital for animals, but the problem is how did animals acquire those sensations through evolution. In other words, how do we go from a creature that feels no pain nor pleasure to one that does? And how did copulation and eating become pleasurable?

[TeleMad]

Apes Anonymous: And how did copulation ... become pleasurable?

Imagine a population with some animals that find pleasure in reproducing (ignore how this first arose, for this topic) and some that don't. Which group, on average, do you think would reproduce more? Those that find it pleasurable. Now, if there is any genetic underpinnings to that pleasurable sensation, then the group that's doing the more reproducing because it's pleasurable will pass on their "sex is pleasurable" genes to their offspring. So the "sex is pleasurable gene(s)" would spread through the population and become fixed.

[Apes Anonymous]

Thank you for the answer Telemad, what you said is quite sensible but I think that the part you omitted...

Originally Posted by TeleMad

(ignore how this first arose, for this topic)

...is exactly what I'm trying to understand. I apologize for not being very clear. I guess that if I understood how an asexual biological entity evolves into a sexual one, that would solve my problem. I'm afraid that this has to do with the birth of consciousness in animals, because that's a difficult problem.

[pgrmdave]

I don't think it has to do with the birth of consciousness, there is no reason for us to be self-aware to experiance pleasure. Telemad is correct, there is an evolutionary benefit to experiancing pleasure and pain. It would be random mutations, fluctuations in DNA that would cause some people to be more sensitive in some areas than others. The mutations don't necessarily make only the genitals more sensitive, however, those beings that have more sensitive genitals rather than more sensitive [insert other body part here] would have more desire to have sex, resulting in more offspring, who are more likely to have that particular mutation, and spread it.

I am more interested in how life moved from organisms that only had one gender to organisms that had two, and why, if having two genders is a benefit, are there no species that have more than two?

[Apes Anonymous]

Thank you pgrmdave for your input.
When I mentioned consciousness I was referring to the ability to "sense" the environment without necessarily reaching the levels that humans have attained. Now I'm starting to doubt if we can attribute consciousness to an organism without a nervous system. So if a "brain" is necessary to experience pleasure sensation, then the early sexual organisms had to have another incentive for mating. Any ideas?

Originally Posted by pgrmdave

I am more interested in how life moved from organisms that only had one gender to organisms that had two, and why, if having two genders is a benefit, are there no species that have more than two?

Interesting thought, but I think that because 2 is the cheapest way to go, nature would select it over 3 or more because that would be asking too many parters for the survival of the species. So my guess is that if such a species ever developed, chances are it would be extinct.

[Qfwfq]

Originally Posted by Apes Anonymous

(ignore how this first arose, for this topic)[TeleMad]

...is exactly what I'm trying to understand.

Before animals, there were plants. Before there were plants that attracted insects with nectar, there were (and still are) plants that simply release pollen in the wind (which has been around for quite a while). The pollen simply ends up where it ends up. Some of it will just happen to strike the pistillus of a plant of the same species or at least compatible. There you are, neither pleasure nor pain. When insects began to find nourishment in the secretions of plant genitals, they brought an advantage to those plants. If the insects were attracted more to some plants and less to others, even specimens of the same species, guess which ones got the most reproductive advantage?

Now, of course, you might shift the question to: How then did the pollen mechanism come about? Or, how did the insects come about? Or, how did animal forms come about? Or, how did photosynthesis come about? Or, How did multicellular forms and cell differentiation come about?

Nobody knows each and every detail of the whole chain but, with a bit of insight, we can nevertheless understand the overall picture.

[Qfwfq]

Originally Posted by Apes Anonymous

Now I'm starting to doubt if we can attribute consciousness to an organism without a nervous system. So if a "brain" is necessary to experience pleasure sensation, then the early sexual organisms had to have another incentive for mating. Any ideas?

I've had that kind of doubt for quite a while but I'm not all that worried by it.

Replace the notion of pleasure with other reactions to stimuli, even at a more molecular level. What makes a protozoan struggle to ingest a bit of food, and not a speck of something useless or even harmful? One could even say it smells the food and goes up the gradient of concentration. It's all one cell, unlike us it can't have the same organs, the same nervous system etc... Its parts are, mainly, different proteins and these are able to fold and unfold according to conditions. These macromolecules are complicated mechanisms, able to exploit chemical energy nonthermally. Heat only comes in as necessary for diffusion.

How did all this come about? The steps from the organic soup to the first cells haven't been quite agreed on but I think I can see a few things through the mist, even though I'm not a biologist.

[Qfwfq]

Originally Posted by Apes Anonymous

Interesting thought, but I think that because 2 is the cheapest way to go, nature would select it over 3 or more because that would be asking too many parters for the survival of the species. So my guess is that if such a species ever developed, chances are it would be extinct.

I don't quite fully agree but I do agree that 3 wouldn't have terribly more advantage over 2. Two makes the big difference as to diversity amongst offspring. In some cases it might be too much to ask in many cases it would not be a problem. In a sense, there are many examples of more than two, just not at the cellular level. Even on the same heat, females of some species usually have several siblings and might have let more than one guy have a go at it.

Basically I'd say that a scheme for actually more than 2 cells simply didn't show up and wasn't likely to, if it did it brought hardly an advantage, especially compared to promiscuity, although not necessarily so crushingly condemned.