Natural selection in the human race vs. Medical Science

[Browne]

It is sometimes argued that advances in the medical science, by reducing the mortality due to hereditable diseases, result in building a reservoir of unfavourable genes in the human population, and that this will reduce the viability of the human species. Discuss this statement.

 

I have read a few blogs on this topic but none explain about medical science reducing the viability of the human species.

 

Can you please help me out here, it would really help gaining an understanding of this.

Thanks

[Phi for All]

Moderator Note: Thread moved from Relativity to Evolution, Morphology and Exobiology.

 

 

 

Click this link for a similar thread to use as a starting point for your discussion. And consider the fact that our ability to treat ourselves medically was naturally selected for.

Edited March 13, 2010 by Phi for All
Added note.

[StrontiDog]

It is sometimes argued that advances in the medical science, by reducing the mortality due to hereditable diseases, result in building a reservoir of unfavourable genes in the human population, and that this will reduce the viability of the human species.

 

In general, the more diverse the gene pool, the more likely a species is to survive in harsh conditions. By allowing significant portions of the population to survive and breed, which would not have done so in the past, humanity is getting more diverse, not less.

 

The effect of technology and lifespan on our species, in general, is not well understood from an evolutionary perspective. We only have one test case, and the experiment just started.

 

I would offer that without human interference, dogs would not have nearly the genetic diversity that they now have. Perhaps some environmental factor could wipe-out all dog breeds larger than a Chihuahua, and then the entire canine species would be small, annoying and yappy. . .but it would still exist.

 

Without this diversity, they'd go the way of the dodo. I doubt there were any wild dogs that small before domestication and selective breeding (a kind of Eugenics, when you think about it).

 

Besides, too few humans doesn’t seem to be a problem, does it?

 

Bill Wolfe

[Mr Skeptic]

It is sometimes argued that advances in the medical science, by reducing the mortality due to hereditable diseases, result in building a reservoir of unfavourable genes in the human population, and that this will reduce the viability of the human species. Discuss this statement.

 

We have just changed the rules, for now, of what constitutes "fit". Diversity is in general a good thing -- especially when it comes to disease resistance. This is because diseases frequently depend on their host having specific genetics. A change away from that, while it may have a detrimental effect, can also confer resistance to a disease, even a disease we have never been affected with. It is no simple matter to say that a gene is good or bad -- it depends on the environment. Look up sickle cell anemia, and also the delta 32 mutation, for examples of this.

 

So long as we are not losing the beneficial genes, then the extra diversity should be a good thing. Should our society collapse, the maladaptive traits will be weeded out quickly enough. In the meantime, there is also the possibility of extra evolution occurring, since there won't be heavy pressure to maintain genes as they are, allowing them to change more.

 

Also, people like to focus a lot on the "not dying" portion of fitness. In reality, not dying is nearly irrelevant to fitness. What really matters is how many surviving offspring you have. The trick, of course, is that dying before having kids sets your fitness to approximately zero or even negative.

[Browne]

Thanks Phi for All, I did look at that post but didn't find anything about the viability of humans.

 

In general, the more diverse the gene pool, the more likely a species is to survive in harsh conditions. By allowing significant portions of the population to survive and breed, which would not have done so in the past, humanity is getting more diverse, not less.

 

I hadn't considered this point, certainly a great point. Everything else I have learnt has refuted what you have said, yet it makes more sense using other examples in nature.

 

Should our society collapse, the maladaptive traits will be weeded out quickly enough. In the meantime, there is also the possibility of extra evolution occurring, since there won't be heavy pressure to maintain genes as they are, allowing them to change more.

Can evolution still occur even though humans are not isolated to one particular environment? A teacher said evolution can not take place within the human race because reproduction isn't limited to a certain evironment due to advances in technology.This means no human needs to evolve to adapt to a certain environment.

 

is this correct?

 

Thanks.

[Mr Skeptic]

Can evolution still occur even though humans are not isolated to one particular environment? A teacher said evolution can not take place within the human race because reproduction isn't limited to a certain evironment due to advances in technology.This means no human needs to evolve to adapt to a certain environment.

 

is this correct?

 

Thanks.

 

Evolution, simply defined, is a change in the allele frequency of a population. (An allele is a specific "version" of a gene.) Every new mutation generated is a new allele and therefore evolution. Every allele lost is also evolution. Any increase or decrease of a certain allele's frequency is also evolution.

 

This is distinct from speciation and the theory of common ancestry. As a mixed population, we share a common gene pool and therefore cannot speciate -- our alleles are exchanged with each other and so we remain compatible. We will remain a single species, unless perhaps we get reproductively fragmented once more, such as due to space colonization.

[skyhook]

diabetes is a fatal disease in the past when the cause of the disease has not been determined. The people of the past holding the genes would have been limited by natural selection. The people at present will still survive with diabetes, even if they have the diabetes causing genes. Their chance of reproducing is better.

So those holding the genes could be on the increase.

 

 

Can evolution still occur even though humans are not isolated to one particular environment? A teacher said evolution can not take place within the human race because reproduction isn't limited to a certain evironment due to advances in technology.This means no human needs to evolve to adapt to a certain environment.

 

is this correct?

 

Evolution happens all the time to any living things. so, I'll disagree.

[pioneer]

The vast majority of human progress, over the past 10,000 years has been because of the human brain/mind and not because of genetics. Medicine reflects this observed reality. Even if we breed forward regressive and/or defective genes, this will not effect human progress, since the mind is the key. Even someone with a genetic defect can still contribute at the level of the mind. That is what evolves humans through cultural advancements.

 

There is no science genes, which give one a knowledge of science at birth, like an instinct. One has to use the brain, anew, and build up this knowledge through education. Whether one has genetic defects or not, which may require medicine, one can still build up this knowledge base. The human brain, in turn, is also learning to manipulate the DNA, via genetic engineering. This is not the DNA manipulating the DNA, since the process is not random, but based on intelligent design plans via genetic engineering. We tend to look for cause and effect, and not just throw the dice.

 

In many religions, they break down the human entity into body, soul and spirit, with the body or genetics, at the bottom, since that part is close to the animals. This is where genetics is far more important. The soul is connected to our emotional natures and/or the impact of the limbic system on the cerebral. While the spirit is more purely cerebral.

 

The ancients saw these brain aspects of humans, being the human continuity of progress, analogous to genetic evolution. The Divine soul and spirit lives on through teaching and education, where previous products of the human mind continue, even when the body dies. Even with Einstein gone, we can get the mind version of gene transfer, absorbing this theory through mental osmosis. The spirit of Einstein lives on this way even when the genetics are pushing up daisies. His soul is more connected the more human side of him; emotions, which some like to experience by reading an Einstein biography. His soul is alive if the author is able to recreate the ambiance of his life. Both his spirit and soul impact us, even though we don't have any of his genes. It would not have mattered, if he had genetic defects. As long as his soul and spirit live through education, That is how he helped to advance humans.

 

The irony is connected to evolutionary theory, which is why we are discussing this topic. With respect to medicine, the actions and words do not add up. We give evolution lip service in school, but in actions, such as in medicine, we ignore it and do the opposite of what the theory suggests. We would not go into a herd of deer and put extra resources into patching up the sick and weak. This could lead to extinction. Evolution is a product of the human brain, that does not fully explain the reality of human progress. The ancient way makes more sense and is what medicine does in action, but not always via lip service.

[StrontiDog]

Can evolution still occur even though humans are not isolated to one particular environment? A teacher said evolution can not take place within the human race because reproduction isn't limited to a certain evironment due to advances in technology.This means no human needs to evolve to adapt to a certain environment.

 

Largely, yes. It is correct. Though no individual ever evolves, the human species might. Just something to keep in mind, but it's important.

 

A species can remain unchanged for millions of years if its current genetic diversity is sufficient for viability within its niche of the ecosphere. This too, IS evolution. Change doesn't seem to have to occur unless there is some environmental pressure to do so. At which point the species either changes, or becomes extinct.

 

Remember the Coelacanth, which was thought to have been extinct for millions of years. . .until somebody caught one and brought it to the attention of the world.

 

It's what folks mean when they say science is falsifiable. It can be proven false, and it's surely one of science's greatest strengths.

 

Bill Wolfe

[CharonY]

Change doesn't seem to have to occur unless there is some environmental pressure to do so.

Changes will occur. Only they may not persist.