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 Posted - 01/06/2005 : 18:13:55 [Permalink]
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| One factor of many that is affecting human evolution is smoking. It is clear (W.H.O.) that the average smoker that perishes loses about 20 years of their life. Worldwide, 10,000 people are dying every day with smoking/tobacco related diseases, that is 3.65 million per year at the current rate. In 75 years, that is about 274,000,000 people (approx. population of entire U.S.) dying an early death due to smoking. Clearly, smokers are eliminating themselves from the gene pool at an early age, but because that age is generally past the reproductive years, they continue to breed more smokers. However, studies show that fertility among smokers is lower, therefore, they are slowly eliminating themselves from the gene pool. In a few generations when over a billion have died, we may see an evolutionary change that tends to shy away from smoking among human beings. Whew, what a relief. Unfortunately, the affects of smoking on brain function are quite substantial and brains cells are killed by every puff of smoke. Will this cause future generations to be stupider and stupider? I think we can safely say that stupidity will not be bred completely out of the human race. |
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chaloobi
SFN Regular
1620 Posts |
Posted - 01/06/2005 : 18:16:48 [Permalink]
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Dave W:
Another quote from the same article:
quote:
Random genetic drift is a stochastic process (by definition). One aspect of genetic drift is the random nature of transmitting alleles from one generation to the next given that only a fraction of all possible zygotes become mature adults. The easiest case to visualize is the one which involves binomial sampling error. If a pair of diploid sexually reproducing parents (such as humans) have only a small number of offspring then not all of the parent's alleles will be passed on to their progeny due to chance assortment of chromosomes at meiosis. In a large population this will not have much effect in each generation because the random nature of the process will tend to average out. But in a small population the effect could be rapid and significant.
Further discussion in the block quote that follows talks about two reproductively isolated populations gradually diverging via genetic drift, but the effect in vast populations like that of humanity today, constantly intermixing, has got to be very small. Yes, it still technically affirms the question "Is evolution occurring" but it's still minimal on such a large scale. Clearly genetic drift is only significant when populations are constantly fragmenting and isolating from each other, forced into situations of frequent in-breeding, such as in the natural world with animals and in pre-agricultural revolution humanity. I still believe it is valid that humanity today is largely free of the effects of genetic drift. A better argument can be made for the effects of natural selection on present day humanity. |
-Chaloobi
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chaloobi
SFN Regular
1620 Posts |
Posted - 01/06/2005 : 18:19:00 [Permalink]
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quote:
Originally posted by Doomar_
One factor of many that is affecting human evolution is smoking. It is clear (W.H.O.) that the average smoker that perishes loses about 20 years of their life. Worldwide, 10,000 people are dying every day with smoking/tobacco related diseases, that is 3.65 million per year at the current rate. In 75 years, that is about 274,000,000 people (approx. population of entire U.S.) dying an early death due to smoking. Clearly, smokers are eliminating themselves from the gene pool at an early age, but because that age is generally past the reproductive years, they continue to breed more smokers. However, studies show that fertility among smokers is lower, therefore, they are slowly eliminating themselves from the gene pool. In a few generations when over a billion have died, we may see an evolutionary change that tends to shy away from smoking among human beings. Whew, what a relief. Unfortunately, the affects of smoking on brain function are quite substantial and brains cells are killed by every puff of smoke. Will this cause future generations to be stupider and stupider? I think we can safely say that stupidity will not be bred completely out of the human race.
The real question is whether or not smokers have a genetic trait that tends to make them want to smoke. If it's just socio-economic circumstance or learned behavior from parents it's not necessarily an evolutionary change. |
-Chaloobi
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filthy
SFN Die Hard
USA
14408 Posts |
Posted - 01/06/2005 : 21:06:37 [Permalink]
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quote:
Originally posted by chaloobi
quote:
Originally posted by Doomar_
One factor of many that is affecting human evolution is smoking. It is clear (W.H.O.) that the average smoker that perishes loses about 20 years of their life. Worldwide, 10,000 people are dying every day with smoking/tobacco related diseases, that is 3.65 million per year at the current rate. In 75 years, that is about 274,000,000 people (approx. population of entire U.S.) dying an early death due to smoking. Clearly, smokers are eliminating themselves from the gene pool at an early age, but because that age is generally past the reproductive years, they continue to breed more smokers. However, studies show that fertility among smokers is lower, therefore, they are slowly eliminating themselves from the gene pool. In a few generations when over a billion have died, we may see an evolutionary change that tends to shy away from smoking among human beings. Whew, what a relief. Unfortunately, the affects of smoking on brain function are quite substantial and brains cells are killed by every puff of smoke. Will this cause future generations to be stupider and stupider? I think we can safely say that stupidity will not be bred completely out of the human race.
The real question is whether or not smokers have a genetic trait that tends to make them want to smoke. If it's just socio-economic circumstance or learned behavior from parents it's not necessarily an evolutionary change.
Agreein' with 'loobi. Smoking is an aquired, social habit resulting in addiction. It only shortens the life of the indivdual, rather than make any changes in populations as a whole. I don't think it has any bearing on the evolution of the species. Most smokers still manage to have children.
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"What luck for rulers that men do not think." -- Adolf Hitler (1889 - 1945)
"If only we could impeach on the basis of criminal stupidity, 90% of the Rethuglicans and half of the Democrats would be thrown out of office." ~~ P.Z. Myres
"The default position of human nature is to punch the other guy in the face and take his stuff." ~~ Dude
Brother Boot Knife of Warm Humanitarianism,
and Crypto-Communist! 
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| Edited by - filthy on 01/06/2005 21:09:07 |
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Dave W.
Info Junkie
USA
26022 Posts |
Posted - 01/06/2005 : 21:37:23 [Permalink]
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quote:
Originally posted by chaloobi
Further discussion in the block quote that follows talks about two reproductively isolated populations gradually diverging via genetic drift, but the effect in vast populations like that of humanity today, constantly intermixing, has got to be very small. Yes, it still technically affirms the question "Is evolution occurring" but it's still minimal on such a large scale. Clearly genetic drift is only significant when populations are constantly fragmenting and isolating from each other, forced into situations of frequent in-breeding, such as in the natural world with animals and in pre-agricultural revolution humanity. I still believe it is valid that humanity today is largely free of the effects of genetic drift. A better argument can be made for the effects of natural selection on present day humanity.
Okay, allow me to highlight one phrase from the two sentences you bolded.In a large population this will not have much effect in each generation because the random nature of the process will tend to average out. But in a small population the effect could be rapid and significant. What Suzuki is saying is simply this: in a small population, drift can have a dramatic effect in a short time. He's not saying that its effect is insignificant in a large population over a long period, but only insignificant in a large population in a generation (or even two or three, depending on its size). A random walk through a population of billions will still eventually eliminate or blanket a trait.
Note again: I don't disagree that drift can be responsible for relatively massive and quick genetic change in a small population. I do disagree that its effect is inconsequential in a large population over long periods of time.
Here's the problem, after all: you're claiming that natural selection right now has zero effect on humanity, and so are suggesting that we're not evolving at all. But the simple fact of the matter is that evolution doesn't have to happen in any particular time frame, and the theory of punctuated equilibria suggests that evolution is extremely sluggish for most of a species' history. Doesn't mean they're not changing, just that the rate is very slow. Drift can account for genetic change in the absence of selectors.
I wish I could remember the name of the muscle right now, but there's a muscle that all our ape cousins have which can flex all five toes at once. Most humans don't have it, but some 10% or so have a twisted little wreck of a version of it (it's possible for it to be entirely tendon, for example). It should be obvious that this muscle presents no selection pressure of any sort (we're fine without it, it doesn't work when we've got it, and it presents no sexual characteristics), so without the drift of a mutation which disables the building of the muscle, we should all have it still. But we don't. In a few thousand or million more generations, this muscle may be non-existant in humans. Or, we may all have it. That's drift for you. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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chaloobi
SFN Regular
1620 Posts |
Posted - 01/07/2005 : 07:20:02 [Permalink]
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quote:
Originally posted by Dave W.
quote:
Originally posted by chaloobi
Further discussion in the block quote that follows talks about two reproductively isolated populations gradually diverging via genetic drift, but the effect in vast populations like that of humanity today, constantly intermixing, has got to be very small. Yes, it still technically affirms the question "Is evolution occurring" but it's still minimal on such a large scale. Clearly genetic drift is only significant when populations are constantly fragmenting and isolating from each other, forced into situations of frequent in-breeding, such as in the natural world with animals and in pre-agricultural revolution humanity. I still believe it is valid that humanity today is largely free of the effects of genetic drift. A better argument can be made for the effects of natural selection on present day humanity.
Okay, allow me to highlight one phrase from the two sentences you bolded.In a large population this will not have much effect in each generation because the random nature of the process will tend to average out. But in a small population the effect could be rapid and significant. What Suzuki is saying is simply this: in a small population, drift can have a dramatic effect in a short time. He's not saying that its effect is insignificant in a large population over a long period, but only insignificant in a large population in a generation (or even two or three, depending on its size). A random walk through a population of billions will still eventually eliminate or blanket a trait.
Note again: I don't disagree that drift can be responsible for relatively massive and quick genetic change in a small population. I do disagree that its effect is inconsequential in a large population over long periods of time.
I was thinking about that last night and actually anticipated your response. The rapidity with which genetic drift changes a population is inversely proportional to the population's size. Small populations change very rapidly. Presumably VAST populations, like the Earth's billions, would only change on a very SLOW time scale. But the fact is what we are experiencing today - human population on such a vast scale - is:
1. Unprecedented in history, so study of past evolutionary change may not even apply and new, previously unseen, mechanisms of change may likely take effect and surprise everyone.
2. Likely temporary, so the point in 1 is moot.
quote:
Here's the problem, after all: you're claiming that natural selection right now has zero effect on humanity, and so are suggesting that we're not evolving at all.
Please note I've already contradicted my OP several times, even in posts I've written directly to your attention. For the record, I don't believe natural selectors have been removed from the majority of human population.
quote:
But the simple fact of the matter is that evolution doesn't have to happen in any particular time frame, and the theory of punctuated equilibria suggests that evolution is extremely sluggish for most of a species' history. Doesn't mean they're not changing, just that the rate is very slow. Drift can account for genetic change in the absence of selectors.
Agreed. And in this case, even if natural selection had been eliminated from all of humanity in the last 100 years due to unchecked population grown and powerful social support structures, it's only a temporary situation. Indeed, it appears the condition of unchecked population growth is already unravelling. And the condition of social support structures by no means ever existed for anything like all of humanity, or even the majority for that matter.
quote:
I wish I could remember the name of the muscle right now, but there's a muscle that all our ape cousins have which can flex all five toes at once. Most humans don't have it, but some 10% or so have a twisted little wreck of a version of it (it's possible for it to be entirely tendon, for example). It should be obvious that this muscle presents no selection pressure of any sort (we're fine without it, it doesn't work when we've got it, and it presents no sexual characteristics), so without the drift of a mutation which disables the building of the muscle, we should all have it still. But we don't. In a few thousand or million more generations, this muscle may be non-existant in humans. Or, we may all have it. That's drift for you.
Right. Drift is about probability and radom chance in the absence of an overt selector. What happens to a mutation that produces a trait that's not selectable? It gets passed on and on or it dies out. Random chance. |
-Chaloobi
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chaloobi
SFN Regular
1620 Posts |
Posted - 01/07/2005 : 07:25:12 [Permalink]
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quote:
Originally posted by filthy
quote:
Originally posted by chaloobi
quote:
Originally posted by Doomar_
One factor of many that is affecting human evolution is smoking. It is clear (W.H.O.) that the average smoker that perishes loses about 20 years of their life. Worldwide, 10,000 people are dying every day with smoking/tobacco related diseases, that is 3.65 million per year at the current rate. In 75 years, that is about 274,000,000 people (approx. population of entire U.S.) dying an early death due to smoking. Clearly, smokers are eliminating themselves from the gene pool at an early age, but because that age is generally past the reproductive years, they continue to breed more smokers. However, studies show that fertility among smokers is lower, therefore, they are slowly eliminating themselves from the gene pool. In a few generations when over a billion have died, we may see an evolutionary change that tends to shy away from smoking among human beings. Whew, what a relief. Unfortunately, the affects of smoking on brain function are quite substantial and brains cells are killed by every puff of smoke. Will this cause future generations to be stupider and stupider? I think we can safely say that stupidity will not be bred completely out of the human race.
The real question is whether or not smokers have a genetic trait that tends to make them want to smoke. If it's just socio-economic circumstance or learned behavior from parents it's not necessarily an evolutionary change.
Agreein' with 'loobi. Smoking is an aquired, social habit resulting in addiction. It only shortens the life of the indivdual, rather than make any changes in populations as a whole. I don't think it has any bearing on the evolution of the species. Most smokers still manage to have children.
It is possible, however, that some people are more prone to addiction than others due to some genetic trait. That appears to be the case with alcoholism, afterall. But with smoking, the vast majority of smokers breed successfully before they ever get any negative effects from their addiction. On the other hand, children of mother's who smoke during pregnancy have adverse health effects. Ditto for chidlren that grow up with parents blowing smoke in their faces for their whole lives. Anecdotally, my mother smoked until I was 12 or so. I'm the youngest of 5 and there are now a total of 15 confirmed grandchildren and another two suspected (don't ask). Our family TFR is well above the US average. |
-Chaloobi
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Dude
SFN Die Hard
USA
6891 Posts |
Posted - 01/08/2005 : 19:44:01 [Permalink]
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After reading this thread it seems that chaloobi is of the opinion that evolution is somehow necessary.
If a species is well suited to their environment, then natural selection simply does not occur. Nor is it in any way necessary under this condition.
The platypus is a good example. The species is millions of years old (supported by fossil evidence) and relatively unchanged. It's well suited to it's environment.
Currently humans hold a position that could be called well adapted to our environment. There is no natural selection (except in certain sub-populations) that grossly effects our species.
Other mechanisms of evolution, as presented by Dave_W, occur all the time. They are not as dramatic in the short term (speaking in geological time here, 10k-100k year spans) but can have some impact over longer time frames.
Again, it seems from the tone (and please feel free to correct me if wrong) chaloobi, that you are saying that evolution via some method of selection is necessary.
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Ignorance is preferable to error; and he is less remote from the truth who believes nothing, than he who believes what is wrong.
-- Thomas Jefferson
"god :: the last refuge of a man with no answers and no argument." - G. Carlin
Hope, n.
The handmaiden of desperation; the opiate of despair; the illegible signpost on the road to perdition. ~~ da filth |
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chaloobi
SFN Regular
1620 Posts |
Posted - 01/09/2005 : 16:56:34 [Permalink]
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quote:
Originally posted by Dude
After reading this thread it seems that chaloobi is of the opinion that evolution is somehow necessary.
If a species is well suited to their environment, then natural selection simply does not occur. Nor is it in any way necessary under this condition.
The platypus is a good example. The species is millions of years old (supported by fossil evidence) and relatively unchanged. It's well suited to it's environment.
Currently humans hold a position that could be called well adapted to our environment. There is no natural selection (except in certain sub-populations) that grossly effects our species.
Other mechanisms of evolution, as presented by Dave_W, occur all the time. They are not as dramatic in the short term (speaking in geological time here, 10k-100k year spans) but can have some impact over longer time frames.
Again, it seems from the tone (and please feel free to correct me if wrong) chaloobi, that you are saying that evolution via some method of selection is necessary.
I made several false starts to answer your question and I just concluded that I'm not sure if it even makes any sense to regard the issue this way. On the one hand I would say that without evolution, extinction for a species will eventually follow. But that's not correct because it follows anyway. When a species evolves to take advantage of or deal with changes in it's overall environment, it becomes a new species, eventually. And the old either continues or dies out.
Evolution transcends species - it's not about the survival of an individual or an entire species. It's about the survival of life. Or is it about specific genes? The gene for thought or for language or for whatever - obviously it's more complicated than that, but just for discussion sake. So, it's a more like this: if a species doesn't evolve, it's entire genotype might be lost in the face of a changing environment.
If that happened to humanity, what would be lost? Well, everything that distinguishes humanity from other animals - our culture, our accumulated information and ideas, our intelligence and reasoning abilities. These might be lost if humanity never evolved again and our minds were not enough to deal with some kind of cataclysm. I'd say that would be a significant loss. But does it really matter anyway? If the universe is truely as we understand it today, sans religion, then I'm not sure. |
-Chaloobi
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Dave W.
Info Junkie
USA
26022 Posts |
Posted - 01/09/2005 : 20:48:06 [Permalink]
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quote:
Originally posted by chaloobi
So, it's a more like this: if a species doesn't evolve, it's entire genotype might be lost in the face of a changing environment.
If a species does evolve, it's entire genotype might be lost in the face of a changing environment.
Say, for example, that in the face of human-induced global warming, brown bears evolve into a relatively hairless bear. And then comes the next ice age. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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Dude
SFN Die Hard
USA
6891 Posts |
Posted - 01/10/2005 : 00:08:20 [Permalink]
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quote:
So, it's a more like this: if a species doesn't evolve, it's entire genotype might be lost in the face of a changing environment.
Evolution is necessary only in the context of the continuation of life. The selection pressures of the environment only effect a species if that species is not well adapted to it's environment. There are several instances in the fossil record of specific species occuring relatively unchanged for millions of years. There are even some living examples, I believe I mentioned the platypus.
As Dave_W pointed out, evolution via natural selection can drastically alter a species in relatively short time (geologically speaking), thereby erasing their specific genes from the planetary pool. Also, extincion events (like the one currently occuring to amphibians accross the globe) can erase the genome of entire species.
If humans desire to remain human (as we currently define it) then continued evolution from natural selection would be undesirable.
We are, I believe, unique on this planet as the only species to evolve an intellect that is capable of deliberate introspection and awareness of our consciousness. This gives us a tremendous advantage over anything else living. The ability to adapt by deliberate manipulation of our environment. (i.e. it's cold therfore we make clothes and shelter, stuff like this that no other species is capable of) We are learning at a tremendous rate, we (as a race) double our knowledge every few years. (think I read someplace that the human race has aquired more knowledge in the last 50 years than in the entire history of the race previously) And so on.
Our ability to manipulate our environment continues to grow. This is an unprecedented (in nature) ability. This ability, essentially, makes us one of the most well adapted species to have ever evolved. Odds are, barring some massive disaster like a large/dense meteor strike or a nuclear war, that we will be around for a long time.
Even so, there will be some change from the slower types of evolution. In 100k years, assuming we are still around, we'll probably have some significant differences from humans alive today. But we'll probably still be human.
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Ignorance is preferable to error; and he is less remote from the truth who believes nothing, than he who believes what is wrong.
-- Thomas Jefferson
"god :: the last refuge of a man with no answers and no argument." - G. Carlin
Hope, n.
The handmaiden of desperation; the opiate of despair; the illegible signpost on the road to perdition. ~~ da filth |
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beskeptigal
SFN Die Hard
USA
3834 Posts |
Posted - 01/10/2005 : 04:12:42 [Permalink]
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The reason small populations can experience larger changes genetically is that they have a proportionally smaller gene pool.
The mechanism of new species evolving requires isolation from the main group. So it isn't necessarily drastic climate change or other obvious environmental influence. Something as simple as mate selection can lead to different species. Big environmental changes certainly can lead to big evolutionary changes, but evolution is multi-factorial.
Humans in all areas of the world have sufficient genetic material in common so as to define us as all one race. As long as we continue to interbreed, and we do, genetic mutations are mixed into a very large pool. If any of our group were to evolve away from that common genetic base, the group would have to become isolated.
If we sent a reproducing group to populate an outpost on Mars, we would have the isolation required for new species to evolve. The offspring could all survive, therefore no special selection would occur and the group would still drift genetically in a different direction than the population left on Earth.
Survival of the fittest and natural selection are really dated terms. Though natural selection is closer than survival of the fittest. There are many factors involved in the process.
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chaloobi
SFN Regular
1620 Posts |
Posted - 01/10/2005 : 09:05:37 [Permalink]
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quote:
Originally posted by Dave W.
quote:
Originally posted by chaloobi
So, it's a more like this: if a species doesn't evolve, it's entire genotype might be lost in the face of a changing environment.
If a species does evolve, it's entire genotype might be lost in the face of a changing environment.
Say, for example, that in the face of human-induced global warming, brown bears evolve into a relatively hairless bear. And then comes the next ice age.
Yes of course, but not in one fell swoop such as if all humans were suddenly extinct.
BTW - I'm kinda hoping that the biggest benefit of global warming will be an interuption of the ice-age cycle. That'd be worth losing a bit of coastline, wouldn't it? |
-Chaloobi
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| Edited by - chaloobi on 01/10/2005 09:06:42 |
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Dude
SFN Die Hard
USA
6891 Posts |
Posted - 01/10/2005 : 11:16:07 [Permalink]
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quote:
{snip}natural selection are really dated terms.
Natural selection is not a dated term.
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Ignorance is preferable to error; and he is less remote from the truth who believes nothing, than he who believes what is wrong.
-- Thomas Jefferson
"god :: the last refuge of a man with no answers and no argument." - G. Carlin
Hope, n.
The handmaiden of desperation; the opiate of despair; the illegible signpost on the road to perdition. ~~ da filth |
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BigPapaSmurf
SFN Die Hard
3192 Posts |
Posted - 01/10/2005 : 14:04:06 [Permalink]
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What is dated is the idea of survival of the fittest being the primary/only driving force of evolution. Natural Selection is just the result of the driving evolutionary forces and will never be dated.
Natural selection as applied to modern civilized humans is another matter. As you could argue that we stop natural selection from weeding out the less stable/sucessful traits. We still evolve along as ever though. |
"...things I have neither seen nor experienced nor heard tell of from anybody else; things, what is more, that do not in fact exist and could not ever exist at all. So my readers must not believe a word I say." -Lucian on his book True History
"...They accept such things on faith alone, without any evidence. So if a fraudulent and cunning person who knows how to take advantage of a situation comes among them, he can make himself rich in a short time." -Lucian critical of early Christians c.166 AD From his book, De Morte Peregrini |
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