Natural Selection and Mental Disorders

[Johnny Pneumatic]

This is something that really stumps me, why hasn't Natural Selection weeded out these genes? Why do I have OCD(although non existant with the medication. Thank you science.) and all the other mental disorders that people have? Also why hasn't Natural Selection weeded out the capacity to be susceptible to hallucination?

 

[apoger]

You can extend this to a multitude of condidtions that affect humans. Why hasn't natural selection made us perfectly healthy?

The answer is that we have yet to encounter conditions that would prevent the afflicted from living long enough to breed. Thus the genes have been passed on. If a selective event killed all those with OCD repeatedly, we would eventually find that no humans remain with that trait.

 

[Dancing David]

Like sickle cell anemia, half or partial expression of the trait can be beneficial. In the mental health field there is the 'curse of mental illness' which is that everyone in your family is very succesful, except for the person living with mental illness. I knew clients who had families that all had PhDs and MDs or went to all sorts of high class universities.

 

[epepke]

This is something that really stumps me, why hasn't Natural Selection weeded out these genes? Why do I have OCD(although non existant with the medication. Thank you science.) and all the other mental disorders that people have? Also why hasn't Natural Selection weeded out the capacity to be susceptible to hallucination?

I've thought for a long time that mental disorders were actually beneficial in mild cases, though they might be detrimental in serious cases. Mild cases are more numerous than serious ones, so the genes were selected for.

 

[thatguywhojuggles]

This topic makes me wonder if modern medicine will have an adverse effect on the process of natural selection.

 

[Batman Jr.]

The subject of this thread is a common misconception about Natural Selection. It doesn't produce an idealized version of an organism. It merely eliminates things that would keep it from reproducing, and that's it.

 

[rockoon]

I second that mental illness could have been selected for.

Also another common misconception is that natural selection stops after a person can no longer reproduce. Long lives put more pressure on the resources of an area. It is no suprise that things like cancer are most common right around the time that the individual would have become a burden on his family/tribe.

"Make way for the young"

 

[Xeriar]

This is something that really stumps me, why hasn't Natural Selection weeded out these genes? Why do I have OCD(although non existant with the medication. Thank you science.) and all the other mental disorders that people have? Also why hasn't Natural Selection weeded out the capacity to be susceptible to hallucination?

OCD, autism, and others could certainly be selected for rather than against.

Many others, like Down's Syndrome, are simply mutations that humans are susceptible to, particularly with older parents. Older parents are a more recent phenomenon, so these forms of selection are only beginning to take place.

 

[Jorghnassen]

Evolution is not an optimization process. Besides, what we perceive as detrimental isn't necessarily an impediment to reproduction, and you have to consider simple genetics such as dominant or recessive genes and what not (e.g. if everyone who had blue eyes was exterminated today, then there would still be individuals born with blue eyes in the next generation, same goes if you eliminated all colour-blind people).

 

[El Greco]

This topic makes me wonder if modern medicine will have an adverse effect on the process of natural selection.

There's no Natural Selection anymore on planet Earth. It has been replaced by Human Selection.

 

[Major Billy]

why hasn't Natural Selection weeded out these genes? Why do I have OCD

You haven't told us what symptoms of OCD you have. The common ones are:

1) Avoiding dirt or contamination
2) Excessive tidiness and neatness
3) Excessive washing
4) Constantly checking things (e.g., relocking doors)

Although these behaviors are not that advantageous now, back before there was soap, disinfectant, sanitation, and humans were surrounded by other predators, wouldn't they promote survival?

(PS: #4 is an advantage now if your chosen profession is Engineering)

 

[crimresearch]

How do you know that some mental 'disorders' are not evolutionary advantages...say psychopathy?

 

[Jorghnassen]

There's no Natural Selection anymore on planet Earth. It has been replaced by Human Selection.

Uh? Natural selection is still happening, maybe not at the human level too much (until some major disaster strikes...), but otherwise it has not been superseded by artificial selection (which only applies to selectively bred/genetically modified organisms). On the other hand, one could argue how much the actions of humans has indirectly influenced the course of evolution.

 

[El Greco]

On the other hand, one could argue how much the actions of humans has indirectly influenced the course of evolution.

Of course, that's what it's all about. Let's take man for example. Natural selection is practically over. There's no way that a markedly different human will evolve in some dark corner of Earth. Evolution is terribly slow and has nowhere to hide anymore too. With the advance of genetic engineering the game is over. As far as other species go, we're still "allowing" it as long as it doesn't annoy us but even then, human intervention can (and does) very easily modify, destroy or undo what "natural selection" has been working on for ever. So, even if we continue to "allow" some things to go on, "natural" is now a small subset of "human" and not the other way around.

 

[rockoon]

Of course, that's what it's all about. Let's take man for example. Natural selection is practically over. There's no way that a markedly different human will evolve in some dark corner of Earth.

I believe that the selection effect on man is now almost entirely on the instinctual willingness and ability to have many many babies regardless of how well they might be able to provide for them (basically, the tendency to be reproductively irresponsible) - since society will now make sure that the children survive to have babies of their own, whatever traits increase the chance of reproductive irresponsibility will become more and more represented in our species.

This will continue until we more than max out our resources and are forced to enact laws restricting the number of children a person might have.

This isnt precisely evolution since no genes are being removed, but instead are just more or less represented.

 

[John Bentley]

I believe that the selection effect on man is now almost entirely on the instinctual willingness and ability to have many many babies regardless of how well they might be able to provide for them (basically, the tendency to be reproductively irresponsible) - since society will now make sure that the children survive to have babies of their own, whatever traits increase the chance of reproductive irresponsibility will become more and more represented in our species.

This will continue until we more than max out our resources and are forced to enact laws restricting the number of children a person might have.

This isnt precisely evolution since no genes are being removed, but instead are just more or less represented.

The problem with your thesis is that it isn't happening, at least not in the western world. In fact, the birth rate in the western world is declining. The population increase in so-called third world nations has more to do with the fact that child mortality rates are declining due to medical intervention, so more of the offspring survive. Historically, birth rates decline when 2 things become prevalent in society:
1. Women have the right to say no to more children.
2. Child mortality rates decline enough to put a strain on a family's (or society's) ability to support the increased number of offspring.

Having said this, I agree that population control may become necessary before the above mentioned "natural" birth rate reductions come into play. Or else the thirld world nations will be faced with famine and disease -- which usually lead to wars of expansion and... hey, it's already happening, isn't it?

 

[The idea]

I believe that the selection effect on man is now almost entirely on the instinctual willingness and ability to have many many babies regardless of how well they might be able to provide for them (basically, the tendency to be reproductively irresponsible) - since society will now make sure that the children survive to have babies of their own, whatever traits increase the chance of reproductive irresponsibility will become more and more represented in our species.

The problem with your thesis is that it isn't happening, at least not in the western world. In fact, the birth rate in the western world is declining.

If there are genes that favor reproductive irresponsibility, then isn't it possible that these genes are occurring at an increasing frequency in the western world even if the overall birth rate in the western world is declining?

 

[Johnny Pneumatic]

Re: Re: Natural Selection and Mental Disorders

1) Avoiding dirt or contamination
2) Excessive tidiness and neatness
3) Excessive washing
4) Constantly checking things (e.g., relocking doors)

Although these behaviors are not that advantageous now, back before there was soap, disinfectant, sanitation, and humans were surrounded by other predators, wouldn't they promote survival?

I think these have only been since humans have known about germs and it being good to have stuff clean. You won't wash your hands to remove germs if you don't know germs exist and that some are harmful. I don't know what OCD people obsesed about centuries ago, maybe just having to have stuff sat in just the right place and making sure for the 45th time that the campfire is really put out. I fail to see the survival advantage here.

Who has sex with crazy people? Natural Selection not only effects up to breeding but if you're hallucinating or just being very very anal about certain things having to be "just right" wouldn't this inpinge on taking care of your child?

 

[Johnny Pneumatic]

You can extend this to a multitude of condidtions that affect humans. Why hasn't natural selection made us perfectly healthy?

As far as germs making us sick they evolve to to get around our defences. AIDS anyone? It keeps changing.

 

[Rolfe]

Actually, if "germs" are really efficient, they don't make us sick at all. Or not sick enough to be a real inconvenience, and certainly not sick enough to die. What we call HIV seems to have been perfectly adapted to the Vervet monkey. Lived with its host species in perfect harmony.

The trouble started when it got into a species not its natural host. It's not in the virus's interests to kill its host. It seems to be blind luck that this particular virus changes its antigenic structure so fast, as far as I know.

Much of the microbial mayhem wreaked in the animal kingdom is caused by organisms which have got into species not their natural hosts, and are thus causing much more serious damage than they'd probably prefer to, given a choice.

(OK, if you're a cold virus, it's to your advantage to make your host sneeze. I'm talking about serious illness and death.)

Rolfe.