Humans Evolving Negativley

[kaos]

This is my theory about where human evolution is headed. It makes perfect sense to me, from all that I've learned about biology and evolution. I cannot prove it, and I would approve of any attempt to prove or disprove it. I also welcome any criticism or comments. I wrote it as if it were known and true, but just understand that it is only a theory.

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In the history of life, organisms have evolved by process of elimination, meaning only the fit survive. If an organism is born with a mutated gene that works to it's disadvantage, it dies before it reproduces. This process makes each species do 2 things. One, become more fit for their environment, and two, STAY fit for their environment.

 

Now, let's say an organism manages to do something incredibly stupid. Let's say it reproduces no matter how unfit for the environment it is. While this will not shrink the population, it WILL cause it's quality of life to drop. For example, mice that are blind and deaf live in a protected environment where they can reproduce, despite their disadvantages.

Example: A child is born with a gene that has a 75% chance of causing deadly stomach cancer. His kids are able to have their stomaches removed and adjust to a specialized diet. They live normal lives and have more kids that also have the defect and also need to have their stomaches removed. Eventually the defect will make its way into every descendant.

 

Guess what? This is beginning to apply to humans. As we develop medical advances that keep us alive longer, and make us appear more attractive to the opposite sex, we reproduce nomatter how unfit or unhealthy we are. This is beginning to cause a permanent "addiction" to medical technology. Since people are being treated for things that normally should be deadly, they are able to reproduce and pass these defects on to our kids. Our kids will then have to be treated for these defects unless they want to live a low quality or short life.

 

This also happens on a smaller scale with physical appearance and cosmetics.

When a man thinks a women is attractive or vice-versa, it is usually because they are healthy. Such features that we find attractive are markers that mean we are healthy, smart, etc. - basically more fit to reproduce and survive. With all the new cosmetic surgery and improvements, people are cheating their way to appearing healthy and fit, while they might actually be extremely unfit.

Example: People with good immune systems have more attractive natural body scents to people of the opposite sex. When people use perfume or deodorant, they are making themselves appear more attractive to the other sex, or subconsciously, more healthy than they really are.

 

The point is that our medical (and maybe some cosmetic) advances are causing us to become more and more dependent on medical technology, and in the long run, our quality of life may be deteriorating because even the unfit can reproduce.

[bascule]

The thing about humans is: they travel, and settle in distant areas: different cities, different countries. There's lots of genetic mixing. This means the gene pool remains extremely diverse, and since there's no selection driving us towards the bad traiths, there's no real chance for them to become predominant.

[kaos]

True but think about this:

Just one person with a single bad trait could have thousands of decedents. That's a lot of people that have a bad trait, all starting with one problem.

 

Question: Would the genetic variety cause the bad trait to be "stamped out" because of only 50% chance of passing it on between each generation? After just two generations, the chances of passing the genes on is less than 25%?

[silkworm]

The only truly negative trend I can see is the incidence of diabetes in the American population.

[Sisyphus]

Poor eyesight is largely genetic, too, isn't it? The invention of eyeglasses has made it nearly irrelevant, though, and so now it's far more common.

[silkworm]

I think that eyesight may be largely a nutrional issue. I've changed my diet recently and no longer need glasses, and can see better without glasses than I could with glasses a few weeks ago - and poor nutrition is the root cause of macular generation.

[Sayonara]

Poor eyesight is largely genetic, too, isn't it? The invention of eyeglasses has made it nearly irrelevant, though, and so now it's far more common.

Maybe it's not more common, but just easier to spot.

[Sisyphus]

Maybe it's not more common, but just easier to spot.

 

I kind of doubt that, just because I know so many people (myself included) whose eyes are naturally poor enough that we wouldn't be much better than blind without assistance. Of course, you might be right inasmuch as maybe our naturally poor eyes were made worse by lots of reading and other uncommon activities from centuries ago, but that seems rather weak.

 

Silkworm, I'm guessing your eyes weren't that bad to begin with. I don't think you can really deny that it's mostly genetic, can you?

[silkworm]

I don't know Sisyphus. Both of my parents and everyone in my family wears glasses (though none legally blind). But I do know that I could barely see anything except for a few feet in front of my face. Now with the new diet, which I haven't been on all that long or completely, I'm sure I'd test at 20/20 - which I wasn't with my glasses on.

 

I do know that a lot of people suffer from poor nutrition. Who knows how their quality of life can improve if they just eat better, eyesight included - and I'm saying that from personal experience.

[kaos]

What is your new diet silkworm? I want to try that =D

[Sisyphus]

Well, what kind of dietary changes did you have, then? I'd love to try it. (Though I can't imagine how changing my diet will change the shape of my cornea...)

[Anjruu]

The only truly negative trend I can see is the incidence of diabetes in the American population.

 

I had thought that diabetes was not genetic, and caused by poor nutrition. I do know that if you are obese as a child you are more likely to be diabetic as an adult.

 

[silkworm]

What is your new diet silkworm? I want to try that =D

 

It's the calorie restricted nutrient dense diet that science has shown to improve not only the longevity but the quality of life on everything that it's been used on except fruit flies. Not only has my eyesight improved, but my energy level is immense, my need for sleep marginal, my short term memory is the best its ever been, my long term memory is coming back all the time, I can even now look at a control panel for a moment and then control something I'm new too without looking at it, and my memory of things I've used before has returned, etc. etc. Basically, I feel pretty damned good. You pretty much have to design it yourself though, and work your way towards it, but the point is low calories/high nutrition. For example, I eat 1700 calories a day and while most of the calories I get are from eggs and cheese, the rest is from fresh fruits and vegetables.

 

Anjruu, I know 2 people who were born diabetic and my sister has been a diabetic ever since she was 2 - which was discovered after a long illness. I know family history plays a role, how much of one I don't know.

[bascule]

It's the calorie restricted nutrient dense diet that science has shown to improve not only the longevity

 

Last time I brought up caloric restriction SkepticLance had a small fit, but I agree, caloric restriction is our best bet for improving longevity as the less energy our mitochondria process, the fewer free radicals they produce.

[Steph]

Uhm... if we have a cure for something, why is it a problem if more people have it. there may be some economical repercussion, but in the case of glasses at least, those are good. our quality of life is WAY better than it was 50000 years ago.

[CanadaAotS]

What your saying is true - if we were all thrown into the jungle and had to survive.

 

I've always believed that technology is just another adaption, and with us almost an apendage to evolution. If you say, cut the legs off of an entire species of animal I doubt they would survive. Technology is the same, if we suddenly got rid of it, our bodies wouldn't be able to cope without it.

 

By the way, genetic mutations are far more detrimental then beneficial. Thats why human ailments will get worse and worse...

 

EXCEPT good old technology will probably solve the problem... once we completely understand DNA coding humans will no longer be born with DNA abnormalities. so, your theory is true but humans will always evolve and adapt to fix the problem.

[lucaspa]

I would approve of any attempt to prove or disprove it. I also welcome any criticism or comments.

 

I hope you mean this, because there are several flaws in the theory.

 

In the history of life, organisms have evolved

 

Organisms don't evolve. POPULATIONS evolve. Evolution happens to populations, not individuals.

 

by process of elimination, meaning only the fit survive. If an organism is born with a mutated gene that works to it's disadvantage, it dies before it reproduces. This process makes each species do 2 things. One, become more fit for their environment, and two, STAY fit for their environment.

 

Read Darwin. Natural selection is a process of PRESERVATION, not elimination. NS preserves good designs and passes them on to the next generation.

 

Now, let's say an organism manages to do something incredibly stupid. Let's say it reproduces no matter how unfit for the environment it is.

 

Natural selection is about numbers. It's not that an "unfit" individual will not reproduce AT ALL, but that it will have LESS offspring than those who are fitter for that particular environment.

 

However, this all depends on competition for scarce resources. No competition, no evolution.

 

While this will not shrink the population, it WILL cause it's quality of life to drop. For example, mice that are blind and deaf live in a protected environment where they can reproduce, despite their disadvantages.

 

Then blindness is NOT a disadvantage in that particular environment, is it? You are working with the fallacy that some traits are universally good and some are universally bad. That's simply not true.

 

Every trait comes with costs as well as benefits. It takes energy during embryonic development to make an eye. An eye is vulnerable to damage. If the environment is such that eyes are not needed, then having eyes are a DISadvantage. That's why we see the loss of eyes in the evolution of species that live underground. There is no benefit to counter the cost.

 

Example: A child is born with a gene that has a 75% chance of causing deadly stomach cancer. His kids are able to have their stomaches removed and adjust to a specialized diet. They live normal lives and have more kids that also have the defect and also need to have their stomaches removed. Eventually the defect will make its way into every descendant.

 

No, it won't. That would happen ONLY if this lineage has MORE kids than all other lineages. Why would this be so? What this does is keep the allele(s) in the population, but it doesn't increase the frequency in the population.

 

Since people are being treated for things that normally should be deadly, they are able to reproduce and pass these defects on to our kids. Our kids will then have to be treated for these defects unless they want to live a low quality or short life.

 

So? All this means is that our "environment" now includes medical technology. You have also overlooked the possibility of other advantageous traits. Let's say your child with an allele for stomach cancer later in life also has an allele for absolute resistance to Ebola virus. By keeping that individual alive and his having children, we now also have insurance against an outbreak of Ebola -- those people with the resistant allele will survive -- even with the risk of stomach cancer.

 

A problem with your thesis is that you think you are smarter than natural selection. You aren't. Natural selection can balance ALL the millions of variables in our environment, constantly selecting the best designs available. You, OTOH, look only at a couple of obvious traits, mistakenly pick traits that you think are "good", and would eliminate everything else in that genome as you eliminate the person. Losing that valuable genetic material from the population.

 

Example: People with good immune systems have more attractive natural body scents to people of the opposite sex. When people use perfume or deodorant, they are making themselves appear more attractive to the other sex, or subconsciously, more healthy than they really are.

 

So? And if the geek with the bad immune system is a genius? So he uses Tag body spray and fathers several children. Yes, the children MAY have his poor immune system, but they also may have his higher IQ. And some of the children will have their mother's good immune system AND their father's higher IQ.

 

Remember what I said about competition? You are assuming no competition for the medical treatments. Yet that isn't true, is it? The cosmetic surgery you describe is not covered by insurance and is expensive. So not everyone can afford it. Those that can have demonstrated the ability to compete for money. Thus, they have already shown themselves to be "fit". Even if they buy cosmetic surgery for their children, the children will inherit the alleles the parents had that made them successful competitors in the marketplace. And if the children are successful, then the grandchildren will get the surgery. And there you have it: the more "fit" are having differential reproductive success.

[lucaspa]

By the way, genetic mutations are far more detrimental then beneficial. Thats why human ailments will get worse and worse...

 

That's not true. 997.4 mutations out of 1,000 are either neutral or beneficial. Only 2.6 out of a 1000 have any direct effect on lifespan or reproduction.

 

Human health now is much better, due mostly to better nutrition. Most ailments come from the environment, not mutations.

 

DNA coding humans will no longer be born with DNA abnormalities. so, your theory is true but humans will always evolve and adapt to fix the problem.

 

It's possible that, someday, we can change DNA sequences such that no one is born with muscular dystrophy, for instance. But if we wipe out ALL "DNA abnormalities", then we are also destroying the genetic variability within the species. When that happens, we will become extinct. As I said in the previous post: we are not nearly as smart as natural selection. The moment we really start tinkering with the genes to produce a "better" human, then we are hanging out a sign: "extinction sale, everything must go"

[CanadaAotS]

Oh well I read somewhere that more are detrimental then beneficial.

[CharonY]

That's not true. 997.4 mutations out of 1,000 are either neutral or beneficial

Wait a tick. How was that determined (from a paper, possibly?)? And more importantly, how many of these were neutral and how many beneficial? I would assume that the vast majority should be neutral and only a fraction beneficial.

As such lumping both data sets together would not allow a direct comparison with detrimental mutations.

[Sayonara]

Yes, I agree - that kind of highly specific statement really ought to be referenced.

[lucaspa]

Wait a tick. How was that determined (from a paper, possibly?)? And more importantly, how many of these were neutral and how many beneficial? I would assume that the vast majority should be neutral and only a fraction beneficial.

 

PD Keightley and A Caballero, Genomic mutation rates for lifetime reproductive output and lifespan in Caenorhabditis elegans. Proc. Natl. Acad. Sci. USA 94: 3823-3827, 1997

 

This study documents the rate of deleterious mutations in the worm C. elegans. Because they are hermaphroditic, the authors were able to separate the worms and run parallel populations descended from a single individual. By maintaining independent sublines, the effect of selection could be minimized, and thus the deleterious mutations could be kept in the population. Lethal mutations are still lethal, but the experimental design allows accumulation of deleterious mutations (as well as neutral mutations) and then the effect on lifespan and production of viable offspring, both of which are measurements of fitness. The estimated deleterious mutation rate per haploid genome (the whole organism) was 0.0026, or 2.6 per thousand.

 

"Deleterious" refers to mutations that directly shorten lifespan or decrease the viability or number of offspring. "Beneficial" and "neutral" apply only to particular environments. There is no such thing as a universally beneficial trait. Every trait comes with costs as well as benefits. Change the environment and what was once beneficial is now detrimental.

 

Other population studies indicate that the vast majority of mutations are neutral in any particular environment.

[lucaspa]

Oh well I read somewhere that more are detrimental then beneficial.

 

And where was that? Creationist literature often makes this claim, but the citations are studies done in the 1930s. This was done with massive amounts of x-rays on flies -- causing multiple mutations in the same individual. Also, only naked eye visible "mutations" were looked at. If you are going to massively change the developmental program of an animal, then you are most likely going to change it for the worse. But those studies were designed ONLY to show what was under genetic control, NOT to study the effect of mutations that occur in nature.

[Edtharan]

Even if more mutations were detrimental than beificial, this doe not mean that they will lower the fitness of an organism. In sexual selection each organism gets 2 coppies of their genome, each from a different parent. Any bad mutations on one can be canceled out by the other. Also DNA has many repair mechanisms that can detect and either repair the mutation, or switch it off so it doesn't cause a problem. And lastly, an bad genome might stop the organism developing in the first place (even in humans, each time an egg is fertilized does not mean that a baby will be produced).

 

So the fact that there are many more bad mutations, than good mutations does not mean that the organism's gene pool will nessisarily become corrupted.

[DaveC426913]

There is no such thing as negative evolution. We are always evolving toward some set of selection criteria, never away.

 

Since the physcial "fitness" of a human is no longer critical to its survival, this is not being selected-for anymore (or much, at least).

 

What we are doing is moving from physical evolution to social evolution. It is social traits that now determine who breeds and who does not.