Pain, Evolution and Terminal Cancer.

As some of you may know by now, I am a staunch believer in the theory of evolution, which by the way, I think in no way conflicts with my belief in some Supreme Being. But I do have one question about the “logic” of evolution, if you will. What possible evolutionary advantage could there ever have been to having people feel the sometimes extreme pain that accompanies terminal cancer? Think about it. It certainly never gave our forebearers, at least, any advantage. And since it weakens the person, I can see alot of disadvantage to its place in the survival of the fittest scheme. I was thinking at length about this subject before I posted it now. And I have concluded that, really, much like the brain, there is no “evolutionary logic” to us feeling pain in any of our internal organs. Sure we don’t want to injure them. But that can be accomplished simply by feeling pain in the skin and flesh on the outside of our bodies.

I look forward to hearing other’s thoughts on this matter. And thank you in advance to all who reply :slight_smile:

There doesn’t have to be an evolutionary advantage to any trait that occurs after reproduction. The genes are already passed on and obviously didn’t effect whether the organism made it to the age of reproduction or not. Most cancers occur later in life, long after the person has had children. Our pain response to chronic, fatal illnesses later in life is simply a fossil, if you will, of our nervous systems ability to warn us of injury and death through acute pain.

There’s generally an advantage to detect damage and inform the brain via pain, it’s just not a system that’s complex enough to distinguish between a terminal illness where nothing can be done vs leaning on a hot stove.

I’d also say there’s advantage to feeling pain in the internal organs, the stomach for example. If some food gives a stomach-ache, then there’s somethign wrong with it, and the brain decided not to eat it anymore.

I think you are mistaken on some of the points of evolution. Everything doesn’t have a purpose, or an intended effect, some things just are. Humans have back problems because our upright structure is a modification of structure that originally walked on all fours. It would be great (for me personally) if we didn’t have this problem but there’s no way for it to be selected against, it’s the way we’re built.

As to cancer, most people who get cancer are beyond childbearing years so evolution (for the most part) isn’t really an issue. For the vast history of human development, people died long before they got cancers. If cancers formed ealier and prevented people from having or taking care of children then there would be a selective force at work, but it doesn’t, so there isn’t much selective force keeping us from getting cancers.

Evolution isn’t a force trying to create the perfect human. Whatever works is good enough. Pain is a side effect of the cancer, why should it be selected against? And how would that work? Internal pain could be a signal that you ate something bad, and thus be a useful trait. Or it could be an unavoidable side effect of the way our organs work.

No pain in internal organs? What if you eat something poisonous? Eat a little and feel pain, eat a lot and die. There probably is no “reason” for it (cancer pain) other than that there is no “reason” not to have it. Or, the need to have it in areas where we do outweighs whatever benefit might derive from not having it there.

Or to put it another way, there’s no selective pressure to “turn off” pain receptors due to terminal disease or injury. Your pain receptors work all the time because a mutation that turned off pain receptors when people are about to die or that turned off pain reception from injuries that will lead to death by definition cannot be passed on to the next generation.

Not true, since those genes would have been there all along.

You’re right, I was unclear. What I meant to say was that there is no way those genes could be passed on PREFERENTIALLY…there is no way to differentiate between the two genes selectively.

Just to be perfectly clear, “works” in this case is a synonym for “reproduces”.

Sure there is. If you’re in a lot of pain, you’re less likely to want to have sex and you’re probably less likely to be attractive to the opposite sex.

But the genes Lemur866 specified would turn off the pain receptors for internal organs in old people, so they didn’t suffer from cancer. Since it only effects people beyond “breeding” age, it has no selective advantage.

But I don’t know that we’ve answered the other half of the question from the op: what advantage do pain receptors in internal organs give (or, to put it another way, why do we have pain receptors for internal organs)? Stomach I get, but I’m not sure about everything else. What good did it do for our ancestors for their heart to hurt when it’s injured, since they couldn’t do anything about it anyway?

First, sometimes a heart attack or other problem doesn’t hurt. Think of the stories of people who just drop dead for no apparent reason. Second, the pain of angina due to cardiac conditions often is triggered by exertion. If you slow down or stop what you’re doing, the pain lessens, which is the only thing one could do in pre-open heart surgery days anyway. Third, most of the time heart problems, like cancer, don’t happen during one’s reproductive years, so it doesn’t matter much, evolutionarily speaking.

Pain is nature’s way of telling us to stop doing whatever it is we’re doing. If you feel pain in your organs, you’ve apparently been doing something very wrong.

Suffering as a result of disease would simply be an unpleasant side-effect of that (at least, in an age where there wasn’t much anyone could do about it).

What’s the breeding age for men?

The problem is that humans aren’t animals, we’re humans, we communicate abstract concepts. Old people are valuable resoucres in non-agricultural societies, and that accounts for 99% of our evolutionary history. Actual reproductive age is irrelevant when the individual can talk and remember. The time spent in agrarian and industrial societies has been to short to have any real evolutionary effect yet.

The problem with a a gane that turns off pain in cases of terminal diseases is that it’s useless. A person with a cancer that far advanced is already a failed experiment. If they somehow have genes that will negate thepain those gens won’t confer any reproductive advantage to their offspring and it sure won’t confer any advatage to them. In evolutionary genes that makes then useless. Although they may be a great help individuals they are evolutionary neutral.

There’s simply no way such genes could ever be selected for.

Um, yeah. That was the point.

To answer John Mace’s question, during most of our evolutionary history the maximum breeding age for most men was, what, about 40? I guess the more correct way to say it would be that a gene to turn off the pain receptors of internal organs to avoid the pain of cancer wouldn’t confer enough of a selective advantage to make a difference, since other factors tend to keep the individuals benefitting from such a gene from contributing to the gene pool, and most human offspring would be born to parents that haven’t experienced the effects of the gene.

Story Time!

A man who has never fathered a child is struck with terrible, chronic pain that only gets worse as the weeks go by. He realizes he is going to die soon. Reflecting on his accomplishments, he realizes he wants to leave behind a legacy: A son. He turns his efforts impregnating a woman before he dies. Had he not felt the pain of a terminal illness, he would have just died one day without taking stock of his life and realizing how little time he had to conceive a son.

There you go: A scenario in which the ability to experience the pain of a terminal illness can be an adaptable trait.

Puberty. Pretty much as soon as the hormones kick in, a male is capable of producing a child.

Some scholars have speculated that perhaps puberty hit our ancestors at an earlier age than it does today, due to their shorter lives.

Isn’t the OP’s underlying presumption that evolution works by the survival of individuals through intrinsic advantages just plain wrong?

Are you talking about lifespan or breeding life? I don’t believe we have any data on the former, and should probably assume that the two are roughly equal.