Can current environment effect "natural selection"?
in [Immunology]
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From: Bryan Heit on 30 Jun 2006 10:38 kumar wrote: > In this respect I have few questions/thoughts:- > > 1. Can current/modern environment and lifestyle effect natural process > of "natural selection"? Modern technology most certantly has changed the forces of natural selection. For example, modern medicine has eliminated many of the diseases which used to kill off millions. You can look at the human genome and you'll find mutations that help protect us against diseases such as malaria, cholera, etc. Today, at least in developed nation, selection for these resistance genes no longer exists. The same could be said about mutations which are otherwise bad - PKU gene for example. In fact, some people argue that humans are no longer evolving as our technology has overcome all selection. Except, perhaps, the selection against the most deleterious mutations. Personally speaking, I would argue that the above concept is flawed at a fundamental level - although human technology has most certantly altered selection, it still exists. People often forget that selection doesn't just mean killing off those who aren't well evolved, but also can drive the successful breeding of those who are well evolved. And in modern society we do see differences in the birth rates among people of certain social demographics... > 1. Whether "natural selection" process recognize current environment > esp. prevailing in big cities similarily as natural environment and can > act naturally? Natural selection just means selection driven by the environment. A city is nothing more then another environment, and certantly can impact on selection. For example, people who are more resistant to the effects of pollution, or the diseases which are common in crowded locations, would do well in a city compared to people without these traits. > 2. Do we still have genetic material free from predisposed/inherited > diseases and disorders? All kinds. Over half of your DNA is what scientists call "junk" DNA. Although this DNA is not without a role, it does not code for genes. As such, it is generally considered not to be involved in evolution. Likewise, there are genes which are essentially "shielded" from being involved in diseases. This can occur for a variety of reasons - be it redundancy (i.e. other genes can do the job of the gene in question), or the gene being absolutely required for life (i.e. mutations in it = death). > 3. Whether "getting more predisposed/inherited diseases or disorders" > is an indicator of deviation from "natural selection" and of "survival > of fittest"? Highly unlikely. Firstly, the rates of human evolution are relatively slow, so modern technology simply hasn't been around long enough to have a huge impact in the variation found within the human genome. Secondly, many of the genetic and partially genetic diseases we suffer from today have existed for a long time - descriptions of people with heart disease and diabetes go back as far as ancient Egypt. Lastly, in many cases the gene(s) which impart susceptibility to some diseases actually evolved to protect us from pathogens. For example, the genes which lead to sycle-cell-cell anemia and cystic fibrosis evolved to protect us against malaria and cholera respectively. Likewise, there is some weak evidence that some of the genes which predispose us to diabetes may have evolved to increase our bodies ability to detect some viral pathogens. As such, these genes would be quite old; in some cases old enough that we find similar mutations in our close relatives, such as chimps. Bryan
From: Bryan Heit on 30 Jun 2006 12:41 Kumar, I cam across this on-line presentation which talks directly about natural selection in humans. It'll probably answer most of your questions. I think it is free. http://www.sciencemag.org/multimedia/video/seminars/ Bryan
From: kumar on 30 Jun 2006 23:56 Bryan Heit wrote: > kumar wrote: > > In this respect I have few questions/thoughts:- > > > > 1. Can current/modern environment and lifestyle effect natural process > > of "natural selection"? > > Modern technology most certantly has changed the forces of natural > selection. For example, modern medicine has eliminated many of the > diseases which used to kill off millions. You can look at the human > genome and you'll find mutations that help protect us against diseases > such as malaria, cholera, etc. Today, at least in developed nation, > selection for these resistance genes no longer exists. The same could > be said about mutations which are otherwise bad - PKU gene for example. > > In fact, some people argue that humans are no longer evolving as our > technology has overcome all selection. Except, perhaps, the selection > against the most deleterious mutations. > > Personally speaking, I would argue that the above concept is flawed at a > fundamental level - although human technology has most certantly altered > selection, it still exists. People often forget that selection doesn't > just mean killing off those who aren't well evolved, but also can drive > the successful breeding of those who are well evolved. And in modern > society we do see differences in the birth rates among people of certain > social demographics... Is it so that many diseases, currently developed at epidemeic level as diabetes2, hypertention, cancer etc. may not be there in future due to new treatments? Can't we be naturally evolved to resistance to diseases persisted since long as malaria? How can it be for sure that we made it? Furthur, can't non-exposure or lesser exposure to persisting diseases since long(may also come later) reverse our evolved resistances and tolerances to these diseases on natural selection? > > > 1. Whether "natural selection" process recognize current environment > > esp. prevailing in big cities similarily as natural environment and can > > act naturally? > > > Natural selection just means selection driven by the environment. A > city is nothing more then another environment, and certantly can impact > on selection. For example, people who are more resistant to the effects > of pollution, or the diseases which are common in crowded locations, > would do well in a city compared to people without these traits. Yes, who can be in better natural/real health, more resistent/tollerant or lesser one? Btw, whether a more resistant/tollerant person move to healthful natural environment, can it effect him adversely? > > 2. Do we still have genetic material free from predisposed/inherited > > diseases and disorders? > > > All kinds. Over half of your DNA is what scientists call "junk" DNA. > Although this DNA is not without a role, it does not code for genes. As > such, it is generally considered not to be involved in evolution. > Likewise, there are genes which are essentially "shielded" from being > involved in diseases. This can occur for a variety of reasons - be it > redundancy (i.e. other genes can do the job of the gene in question), or > the gene being absolutely required for life (i.e. mutations in it = death). How these can be expressed if we reverse current environment to natural environment? Can we still aquire purest form of genetic material(somewhat like do interpreted as adam and eve)? > > 3. Whether "getting more predisposed/inherited diseases or disorders" > > is an indicator of deviation from "natural selection" and of "survival > > of fittest"? > > Highly unlikely. Firstly, the rates of human evolution are relatively > slow, so modern technology simply hasn't been around long enough to have > a huge impact in the variation found within the human genome. Secondly, > many of the genetic and partially genetic diseases we suffer from today > have existed for a long time - descriptions of people with heart disease > and diabetes go back as far as ancient Egypt. Lastly, in many cases the > gene(s) which impart susceptibility to some diseases actually evolved to > protect us from pathogens. For example, the genes which lead to > sycle-cell-cell anemia and cystic fibrosis evolved to protect us against > malaria and cholera respectively. Likewise, there is some weak evidence > that some of the genes which predispose us to diabetes may have evolved > to increase our bodies ability to detect some viral pathogens. As such, > these genes would be quite old; in some cases old enough that we find > similar mutations in our close relatives, such as chimps. > > Bryan Disease might have existed since long back(may be type1diabetes only) in somewhat dormant stages, but how is is now showing epidemic type spread? Modern lifestyle is ofter blaimen for this type of spread. If rates of human evolution are relatively slow how can we expect that current environment or current interventions(which are relatively new) can effect our genetic material, causes resistences etc.? Two thoughts are appeared by this discussions:- 1. Can short period of modernization effect our genetic material and natural selection? 2. Are we encouraging reversal of evolved resistences/tollerances due to unnatural interventions of treatments? Making a person healthy by interventions may pass signals to natural selection that problem don't exist so select those without resistent to these problems. Right?
From: kumar on 2 Jul 2006 06:21 kumar wrote: > Bryan Heit wrote: > > kumar wrote: > > > In this respect I have few questions/thoughts:- > > > > > > 1. Can current/modern environment and lifestyle effect natural process > > > of "natural selection"? > > > > Modern technology most certantly has changed the forces of natural > > selection. For example, modern medicine has eliminated many of the > > diseases which used to kill off millions. You can look at the human > > genome and you'll find mutations that help protect us against diseases > > such as malaria, cholera, etc. Today, at least in developed nation, > > selection for these resistance genes no longer exists. The same could > > be said about mutations which are otherwise bad - PKU gene for example. > > > > In fact, some people argue that humans are no longer evolving as our > > technology has overcome all selection. Except, perhaps, the selection > > against the most deleterious mutations. > > > > Personally speaking, I would argue that the above concept is flawed at a > > fundamental level - although human technology has most certantly altered > > selection, it still exists. People often forget that selection doesn't > > just mean killing off those who aren't well evolved, but also can drive > > the successful breeding of those who are well evolved. And in modern > > society we do see differences in the birth rates among people of certain > > social demographics... > > Is it so that many diseases, currently developed at epidemeic level as > diabetes2, hypertention, cancer etc. may not be there in future due to > new treatments? > > Can't we be naturally evolved to resistance to diseases persisted since > long as malaria? How can it be for sure that we made it? > > Furthur, can't non-exposure or lesser exposure to persisting diseases > since long(may also come later) reverse our evolved resistances and > tolerances to these diseases on natural selection? > > > > > 1. Whether "natural selection" process recognize current environment > > > esp. prevailing in big cities similarily as natural environment and can > > > act naturally? > > > > > > Natural selection just means selection driven by the environment. A > > city is nothing more then another environment, and certantly can impact > > on selection. For example, people who are more resistant to the effects > > of pollution, or the diseases which are common in crowded locations, > > would do well in a city compared to people without these traits. > > Yes, who can be in better natural/real health, more resistent/tollerant > or lesser one? > > Btw, whether a more resistant/tollerant person move to healthful > natural environment, can it effect him adversely? > > > > 2. Do we still have genetic material free from predisposed/inherited > > > diseases and disorders? > > > > > > All kinds. Over half of your DNA is what scientists call "junk" DNA. > > Although this DNA is not without a role, it does not code for genes. As > > such, it is generally considered not to be involved in evolution. > > Likewise, there are genes which are essentially "shielded" from being > > involved in diseases. This can occur for a variety of reasons - be it > > redundancy (i.e. other genes can do the job of the gene in question), or > > the gene being absolutely required for life (i.e. mutations in it = death). > > How these can be expressed if we reverse current environment to natural > environment? > Can we still aquire purest form of genetic material(somewhat like do > interpreted as adam and eve)? > > > 3. Whether "getting more predisposed/inherited diseases or disorders" > > > is an indicator of deviation from "natural selection" and of "survival > > > of fittest"? > > > > Highly unlikely. Firstly, the rates of human evolution are relatively > > slow, so modern technology simply hasn't been around long enough to have > > a huge impact in the variation found within the human genome. Secondly, > > many of the genetic and partially genetic diseases we suffer from today > > have existed for a long time - descriptions of people with heart disease > > and diabetes go back as far as ancient Egypt. Lastly, in many cases the > > gene(s) which impart susceptibility to some diseases actually evolved to > > protect us from pathogens. For example, the genes which lead to > > sycle-cell-cell anemia and cystic fibrosis evolved to protect us against > > malaria and cholera respectively. Likewise, there is some weak evidence > > that some of the genes which predispose us to diabetes may have evolved > > to increase our bodies ability to detect some viral pathogens. As such, > > these genes would be quite old; in some cases old enough that we find > > similar mutations in our close relatives, such as chimps. > > > > Bryan > > Disease might have existed since long back(may be type1diabetes only) > in somewhat dormant stages, but how is is now showing epidemic type > spread? Modern lifestyle is ofter blaimen for this type of spread. > > If rates of human evolution are relatively slow how can we expect that > current environment or current interventions(which are relatively new) > can effect our genetic material, causes resistences etc.? > > Two thoughts are appeared by this discussions:- > > 1. Can short period of modernization effect our genetic material and > natural selection? > > 2. Are we encouraging reversal of evolved resistences/tollerances due > to unnatural interventions of treatments? Making a person healthy by > interventions may pass signals to natural selection that problem don't > exist so select those without resistent to these problems. Right? Let us take case of diabetes. If we are suffering and taking insulin, how natural selection can adjust diabetes in next generations? If modern introductions are continuing at increasing rates but side by side modern interventions are also increasing, how "natural selection" will adjust those moden introductions?
From: Bryan Heit on 4 Jul 2006 10:15
kumar wrote: > Bryan Heit wrote: > >>kumar wrote: >> >>>In this respect I have few questions/thoughts:- >>> >>>1. Can current/modern environment and lifestyle effect natural process >>>of "natural selection"? >> >>Modern technology most certantly has changed the forces of natural >>selection. For example, modern medicine has eliminated many of the >>diseases which used to kill off millions. You can look at the human >>genome and you'll find mutations that help protect us against diseases >>such as malaria, cholera, etc. Today, at least in developed nation, >>selection for these resistance genes no longer exists. The same could >>be said about mutations which are otherwise bad - PKU gene for example. >> >>In fact, some people argue that humans are no longer evolving as our >>technology has overcome all selection. Except, perhaps, the selection >>against the most deleterious mutations. >> >>Personally speaking, I would argue that the above concept is flawed at a >>fundamental level - although human technology has most certantly altered >>selection, it still exists. People often forget that selection doesn't >>just mean killing off those who aren't well evolved, but also can drive >>the successful breeding of those who are well evolved. And in modern >>society we do see differences in the birth rates among people of certain >>social demographics... > > > Is it so that many diseases, currently developed at epidemeic level as > diabetes2, hypertention, cancer etc. may not be there in future due to > new treatments? Hopefully. Some of these diseases, like cancer, are an inevitable result of our biology. So people will always get them, but we'll hopefully be able to cure or treat the disease. In the case of diabetes, one day we may be able to vaccinate against it. Others, like hypertension, need not exist today. Exercise and proper diet could wipe that out today... > Can't we be naturally evolved to resistance to diseases persisted since > long as malaria? How can it be for sure that we made it? Some people have evolved resistance to malaria. Sycle-cell anemia represents one such advance. If you have one copy of the sycle-cell gene you're as close to immune to malaria as you can get. However, if you get two copies of that gene you get sycle-cell disease. There are many other mutations which have induced resistance to malaria; some are totally harmless to humans if they get it in 2 copies. As for how we know if a gene provides resistance, it's simple. You look for people who are resistant to a disease (say people who make it through a large outbreak without getting disease) and then use conventional genetic mapping techniques to identify genes which are associated with surviving the disease. Given enough time, and enough people getting sick, you can identify the resistance gene(s). > Furthur, can't non-exposure or lesser exposure to persisting diseases > since long(may also come later) reverse our evolved resistances and > tolerances to these diseases on natural selection? Yes. If you are not exposed to a pathogen we've evolved resistance to can lead, over many generations, to a loss of that gene. The reason being that there is no longer disease selecting for the gene, so there is nothing to keep in in the population. If the gene also has deleterious effects, the gene may even be "forced" out of the population by natural selection. >>>2. Do we still have genetic material free from predisposed/inherited >>>diseases and disorders? >> >> >>All kinds. Over half of your DNA is what scientists call "junk" DNA. >>Although this DNA is not without a role, it does not code for genes. As >>such, it is generally considered not to be involved in evolution. >>Likewise, there are genes which are essentially "shielded" from being >>involved in diseases. This can occur for a variety of reasons - be it >>redundancy (i.e. other genes can do the job of the gene in question), or >>the gene being absolutely required for life (i.e. mutations in it = death). > > > How these can be expressed if we reverse current environment to natural > environment? They're not expressed, ever. Junk DNA just sites around, and doesn't encode for any genes. > Can we still aquire purest form of genetic material(somewhat like do > interpreted as adam and eve)? Not really. At times genes or chunks of DNA will get duplicated during cell division. This can make copies of a gene which can then evolve into something else. But we do not receive "new" DNA from outside our bodies - all we get is what mom & dad give to us. Bacteria are an example of the opposite. Many bacteria can import new DNA from other bacteria, thus giving themselves "new" genes which come from other species. > Disease might have existed since long back(may be type1diabetes only) > in somewhat dormant stages, but how is is now showing epidemic type > spread? Modern lifestyle is ofter blaimen for this type of spread. A lot of the diseases we suffer from now (diabetes being a good example) have existed for a long time. They simply were very rare until recently as people did not live long enough for them to form, and didn't have the lifestyle to increase the risk to the levels we have now. So our longer lives are one of the reasons these diseases are more common, and the other half of the equation is they way we live now (notably diet). But the underlying genetics have been around for thousands, if not hundreds of thousands or millions, of years. > If rates of human evolution are relatively slow how can we expect that > current environment or current interventions(which are relatively new) > can effect our genetic material, causes resistences etc.? In our lifetimes, not much. It takes hundreds or more generations to see significant genetic change, so modern technology isn't likely to have genetic consequences for a long time yet. The obvious exception being genetic engineering. That allows for instantaneous change... > Two thoughts are appeared by this discussions:- > > 1. Can short period of modernization effect our genetic material and > natural selection? No for genetic material, yes for natural selection. Exception to the 'no' being genetic engineering. > 2. Are we encouraging reversal of evolved resi |