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Does Human Intelligence Trump Evolution?





Dennise
As human advancements in machines, food production, nutrition, medicine, shelter and other achievements have eliminated diseases and contribute to longer life spans and longer periods of fertility; one may wonder how these rapid changes affect powerful evolutionary processes that have shaped us for eons. Are humans now the captains of evolution? Is such a statement ridiculously bold or naive?

Any thoughts?
Peterssidan
Evolution goes on as usual. Captains of evolution? Is that when we can change the DNA to design the perfect human?
loremar
The intellectually lower class are the ones busy procreating. Are we really evolving correctly?
Bikerman
err...even if we assume that there is a 'class' system of intelligence, this is not a correct assertion. Number of children equates mainly to economic circumstances and amount of control women have over their own fertility - it has little to do with intelligence. In those countries with a good standard of living and a decent measure of gender equality, the population is static or even shrinking across all demographics.
loremar
This:
Wikipedia wrote:
Demographic studies have indicated that in humans, fertility and intelligence tend to be inversely correlated, that is to say, the more intelligent, as measured by IQ tests, exhibit a lower total fertility rate than the less intelligent.

This:
Wikipedia wrote:
A theory to explain the fertility-intelligence relationship is that while income and IQ are positively correlated,[1] fertility is inversely correlated with income, that is, the higher incomes, the lower the fertility rates and vice versa

And this:
Wikipedia wrote:
Among a sample of women using birth control methods of comparable theoretical effectiveness, success rates were related to IQ, with the percentages of high, medium and low IQ women having unwanted births during a three-year interval being 3%, 8% and 11%, respectively. Since the effectiveness of birth control is directly correlated with proper usage, an alternate interpretation of the data would indicate lower IQ women were more prone to misuse of birth control.
Peterssidan
loremar wrote:
Are we really evolving correctly?

What is correct evolution according to you? You seem to think that people should evolve to be more intelligent but evolution don't care what you think. If being less intelligent is more successful that is what we will evolve towards. Note that IQ is more affected by education than genes. In reality it is very complex and hard to know in what direction evolution will go. At some point the human population will reach its peak and things will change. What happens until then will probably have very limited effect on the human evolution.
loremar
We're trying to survive the 100th gazillionth century and expand across the universe. I'm in favor of humans having larger brains.
Bikerman
As I said, the main influences on fertility rates are economic and gender-equality. The fact that some studies show a correlation between IQ and fertility is not proof of a causal effect (correlation does not imply causation), and in anycase the effect is small when considered against the two factors I've given.

This is fairly easy to demonstrate: just check the actual figures:


The drop in fertility is marked and clearly any effect from IQ is swamped.
Ankhanu
Dennise wrote:
As human advancements in machines, food production, nutrition, medicine, shelter and other achievements have eliminated diseases and contribute to longer life spans and longer periods of fertility; one may wonder how these rapid changes affect powerful evolutionary processes that have shaped us for eons. Are humans now the captains of evolution? Is such a statement ridiculously bold or naive?

Any thoughts?


Bold and naive Wink

It's apparently true that intelligence, or more correctly, culture has had a strong influence upon human evolution, that does not imply that we're "captains of evolution". We're not really in control of evolution, we've simply shifted the dynamic of differential survival and reproductive success away from natural selective pressures and replaced them largely with socio-economic ones, which have little to no biological basis. There has been very little natural selection at play on our species for quite some time, and we do appear to be somewhat evolutionarily static, but that could change rapidly with the right environmental changes; natural selection does apply, but it's fairly weak in influence at the moment.
New technologies are allowing us to directly influence genetics, but, they are still young and fraught with myriad ethical pitfalls, so, as yet, do not apply to humans and our evolution.

That said, we certainly have the capacity to shape our evolution, but, most efforts have been ethically unacceptable. Eugenics, genocide, etc. are all means to this sort of end, but, at the end of the day, they're morally/ethically wrong things to do. We don't mind selecting for beneficial traits in other species, but, when it comes to our own, the $#!t hits the fan, so to speak. There is danger in selecting humans reproducing "beneficial" traits. (I'd suggest treading this topic very carefully, loremar!)


Loremar: Your wiki source is a fine example of the pitfalls of crowd-sourced information can be right, and oh-so wrong at the same time Wink For example, there is no correlation between intelligence and fertility (the ability to conceive young), as your quotes state. However, there are some correlation between intelligence and family size. These are different concepts, though related.
loremar
Ankhanu wrote:
Loremar: Your wiki source is a fine example of the pitfalls of crowd-sourced information can be right, and oh-so wrong at the same time For example, there is no correlation between intelligence and fertility (the ability to conceive young), as your quotes state. However, there are some correlation between intelligence and family size. These are different concepts, though related.

In demographic context, fertility refers to the actual reproduction, in contrast to fecundity(equivalent to fertility in biology), the ability to reproduce. It means that fertility rate equates to family size(per woman), and not the success rate of reproduction. Yes, there is no correlation between intelligence and fecundity. But intelligence and fertility there is.

I am aware,I am going off topic but I was just trying to bring up the irony of human evolution and human intelligence(as said in the OP, our intelligence made us the captain of evolution). As there seems to be some studies that shows average IQ is recently deflating worldwide compare to the past. It's said that Flynn effect is coming to an end.

There's a film titled "Idiocracy" that touches on the subject of intelligence dysgenics. It's about a person who wakes up 500 years later and discovers that he's the smartest man alive.
Bikerman
I was actually taking 'fertility' to mean actual offspring rather than ability to conceive....it seems that the word is used in both senses, though to me the first is a bit weird...
Dennise
Well ... if not "captains" of evolution, how about lieutenants? Remember, natural evolutionary paths are not predetermined .... there is no 'blueprint' other than natural selection based on reproductive survival rates and death rates against environmental, limited food supply, diseases and other detrimental changes.

Were it not for human advances that have enabled command of our environment, longer fertile periods, fertility drugs, elimination of diseases ...... would we still be here? Would our species have flourished as it has?

A fundamental part of the evolutionary process are random DNA changes that are sometimes caused by various forms of radiation; both natural and man-made radiation. As there are now many sources of man-made radiation (e.g. think of Hiroshima/Nagasaki, radiation therapy, nuclear therapy, nuclear power), might these artificial radiation sources be contributing to man-made evolutionary changes?

On the flip side, what about longer human lifetimes? Species success is also dependent on member size - especially members that are no longer fertile and members that contribute little to species success i.e. the aged and feeble. We have many millions of such members, yet we prosper.

Considering the above challenges and threats to our survival success, we have prospered and prevailed to the point that - some say - we now have the capability to annihilate ourselves.

Again I would ask, have we not altered the course of natural evolution and in it's place introduced some form of artificial evolution?
Bikerman
As far as man-made radiation affecting evolution - no, I think not. Perhaps in some small areas of the sea it has had an effect, but considered over the whole the amount of radiation we produce is negligable and indistinguishable from background apart from extremely rare occasions such as the Japanese disaster (and even then the level quickly diminished with distance).

With regard to age - increased age in males means more chance of passing-on a mutation, so arguably having children later might contribute to diversity....The trend, however, is the other way. In the past a few powerful men would breed disproportionately and they would, normally, be 'old'.

The most telling factor, IMHO, is the childhood survival rate. We now have very high survival rates in most of the world. This means that the evolutionary potential of a particular mutation is diminished greatly (if the majority of the population survive, regardless of genetics, then any new mutation which is a benefit to adaption is not going to spread quickly and will most likely disappear as it becomes diluted across the population.
Ankhanu
Dennise wrote:
Well ... if not "captains" of evolution, how about lieutenants? Remember, natural evolutionary paths are not predetermined .... there is no 'blueprint' other than natural selection based on reproductive survival rates and death rates against environmental, limited food supply, diseases and other detrimental changes.

Were it not for human advances that have enabled command of our environment, longer fertile periods, fertility drugs, elimination of diseases ...... would we still be here? Would our species have flourished as it has?

We have changed the survival game through technology, no question. This is why I've said that natural selection is currently a minor player in human evolution, simply, we've reduced the pressure from natural sources on our survival and reproduction. Much of our success as breeders comes from socio-economic factors rather than survival and the like. I wouldn't say that we're directing our evolution at all, however, as very little in our current mating systems is based around normal channels anymore... there's little based on genes directing our mate choices and survivorship... genetically, it's almost as if we're mating randomly, in many ways. This means that there is little pressure to shift allele frequencies in any particular direction; we're almost maintaining a simple equilibrium, perhaps even creating a more generalize, homogenous gene pool, rather than the specialized disequilibria required for directional shifts.

If we didn't have the technological capabilities we do, would we still be here? Almost certainly. Would we be flourishing as we are? No, probably not. It is our technology that allows us to combat and alter the environment to make it suit us, rather than the other way around.

Dennise wrote:
A fundamental part of the evolutionary process are random DNA changes that are sometimes caused by various forms of radiation; both natural and man-made radiation. As there are now many sources of man-made radiation (e.g. think of Hiroshima/Nagasaki, radiation therapy, nuclear therapy, nuclear power), might these artificial radiation sources be contributing to man-made evolutionary changes?

Radiation is a very minor player in the scheme of genetic mutation. Yes, radiation can cause mutation, but in natural systems, it is exceptionally minor. Processes like transcription error and recombination are FAR greater players in the genetic mutation stage than is radiation. Even in anthropogenic systems, radiation is still a relatively minor player, except in instances of acute and/or prolonged exposure, which aren't particularly common. Chemically induced mutation would certainly be a more common issue than radiation.

Dennise wrote:
On the flip side, what about longer human lifetimes? Species success is also dependent on member size - especially members that are no longer fertile and members that contribute little to species success i.e. the aged and feeble. We have many millions of such members, yet we prosper.

Considering the above challenges and threats to our survival success, we have prospered and prevailed to the point that - some say - we now have the capability to annihilate ourselves.

Again I would ask, have we not altered the course of natural evolution and in it's place introduced some form of artificial evolution?

I'd responded to this in my initial post.
Yes. We've somewhat stalled natural evolution in our species, supplanting natural selective pressures with socio-economic ones.
kelseymh
Ankhanu wrote:
Dennise wrote:
Well ... if not "captains" of evolution, how about lieutenants? Remember, natural evolutionary paths are not predetermined .... there is no 'blueprint' other than natural selection based on reproductive survival rates and death rates against environmental, limited food supply, diseases and other detrimental changes.

Were it not for human advances that have enabled command of our environment, longer fertile periods, fertility drugs, elimination of diseases ...... would we still be here? Would our species have flourished as it has?

We have changed the survival game through technology, no question. This is why I've said that natural selection is currently a minor player in human evolution, simply, we've reduced the pressure from natural sources on our survival and reproduction.


I disagree. We have changed the natural selective pressures, because we have altered our environment. Here's one well documented example: nearly all adult primates lose the ability to digest lactose after infancy/childhood. Following the so-called Neolithic Revolution (development of agriculture approximately 10 Ma), those groups of humans which adopted collection of milk from domesticated livestock evolved lactose-tolerance.

Some groups of humans also evolved resistance to malarial parasites (which, along with their vectors, co-evolved with humans) by a modification of how red blood cells develop and form. That evolved modification has the side effect of reducing the cells efficiency for carrying oxygen. So you can investigate the relative selective pressures of malaria vs. anemia in different populations.

[...]
Quote:
We've somewhat stalled natural evolution in our species, supplanting natural selective pressures with socio-economic ones.


There have not been sufficient generations born to isolated groups to draw this conclusion at all. It is at best an unsupported assumption, and at worst a justification for "social Darwinism," but in neither case does it have scientific merit. If I'm incorrect, please provide peer-reviewed citations to support your claim.
Peterssidan
Ankhanu wrote:
genetically, it's almost as if we're mating randomly, in many ways. This means that there is little pressure to shift allele frequencies in any particular direction; we're almost maintaining a simple equilibrium, perhaps even creating a more generalize, homogenous gene pool, rather than the specialized disequilibria required for directional shifts.
Does this mean that the total number of alleles for all genes is declining because we are interbreeding so much, or is it increasing because of the weak selective pressure?
_AVG_
Uhh ... I don't know if I'm out of place here but I doubt that we or any species can really CONTROL evolution since evolution takes place at time scales MUCH larger than the average lifespan of a civilization (!)
I know that there are a lot of science fiction ideas out there about the future ... that someday mankind may "colonize space" or "find a way to sustain life" etc.
And we've only uncovered the tip of the iceberg as far as understanding how DNA and genes work. Nevertheless, we have made progress, and any increase in knowledge, however small is progress.
kelseymh
_AVG_ wrote:
Uhh ... I don't know if I'm out of place here but I doubt that we or any species can really CONTROL evolution since evolution takes place at time scales MUCH larger than the average lifespan of a civilization (!)
I know that there are a lot of science fiction ideas out there about the future ... that someday mankind may "colonize space" or "find a way to sustain life" etc.
And we've only uncovered the tip of the iceberg as far as understanding how DNA and genes work. Nevertheless, we have made progress, and any increase in knowledge, however small is progress.


You're not out of place Smile As to your first point, I think you're specifically addressing human evolution, rather than making a general statement. Humans do, and have been, "controlling evolution" (that is, engaging in artificial selection) for the past 10,000 years or so. Domestication of grain and livestock, breeding of dogs, cats, pigeons, etc. More recently, our (over)use of antibiotics to control the evolution of many species of bacteria.

Your second point may be valid, but is not necessary. Selective breeding never required any understanding of DNA or even of genes. All it required was a rather trivial observation: that organisms (specifically, macroscopic organisms) in a population reproduce sexually with variations of inherited characteristics. When those variations lead (naturally or artificially) to differential reproductive success, the distribution of characteristics in that population changes over time.

There is no difference, except for time, between the artificial breeding of teosinte to become maize, and the natural selection of tetrapod lungfish to become amphibious.
Ankhanu
kelseymh wrote:
I disagree. We have changed the natural selective pressures, because we have altered our environment. Here's one well documented example: nearly all adult primates lose the ability to digest lactose after infancy/childhood. Following the so-called Neolithic Revolution (development of agriculture approximately 10 Ma), those groups of humans which adopted collection of milk from domesticated livestock evolved lactose-tolerance.

This does not really differ from what I said. The development of lactose-tolerance is a fairly anthropogenic change in our biology, rather than a natural selective change. No, it wasn't as directed as proper artificial selection systems, but it was self-induced in large part.

kelseymh wrote:
Some groups of humans also evolved resistance to malarial parasites (which, along with their vectors, co-evolved with humans) by a modification of how red blood cells develop and form. That evolved modification has the side effect of reducing the cells efficiency for carrying oxygen. So you can investigate the relative selective pressures of malaria vs. anemia in different populations.

You're referencing sickle-cell, a preexisting genetic disorder "widespread" throughout the human population. It's not that they've evolved resistance, so much as resistance is a by-product of of the disorder. But, you're right, occurrence of sickle-cell is more prominent in malaria high regions as a result, and this is largely due to basic survival as a result of a natural pressure.

kelseymh wrote:
If I'm incorrect, please provide peer-reviewed citations to support your claim.

Gonna have to get back to you on this. I can't recall exactly where I came across the info in my undergrad, and all the articles I'm finding in my searches today are leading me further in the past than I'm referencing.

To be clear, I recognize that the language I've used has been somewhat strong. It was not my intent to suggest that natural selective pressures do not apply at all to our species, that is clearly fallacious, my point was that their influence has been greatly reduced. Second to, and associated with that point, I am also making reference to agro-urban societies more heavily than more "primitive" societies; "contemporary" society, for which basic survival is no longer a pressing issue.
Dennise
Here are a few more examples of human evolution 'tinkering':
    stem cell research
    genetic manipulation e.g. fruits, grain and vegetables
    cloning .... well not yet but some day?

and ---

Keeping fertile people - with deadly congenital diseases - alive through medical advances. Would evolutionary pressures otherwise reduce or eliminate such diseases by eliminating or limiting offspring? Instead, do some medicines enable perpetuation of defective genes causing certain diseases? It's horrendous to consider - and hypothetical - but what might happen if we completely halted all cancer research and treatment - other than palliative care? Would cancer gradually die out over time .... a long time? It is my understanding that sharks and perhaps other animals never get cancer.

Of course my statements ignore the important ethical side of evolutionary 'tinkering'. My intent is simply to learn how thinkers in this forum view and feel about human interference/control with/over evolution.
Peterssidan
Quote:
Keeping fertile people - with deadly congenital diseases - alive through medical advances. Would evolutionary pressures otherwise reduce or eliminate such diseases by eliminating or limiting offspring? Instead, do some medicines enable perpetuation of defective genes causing certain diseases?
If these people still get children the answer is yes to both questions.

Quote:
It's horrendous to consider - and hypothetical - but what might happen if we completely halted all cancer research and treatment - other than palliative care? Would cancer gradually die out over time .... a long time? It is my understanding that sharks and perhaps other animals never get cancer.
I don't think cancer would die out. Animals can also get cancer. I think the biggest reason why cancer is such a big problem for humans is that we get older than what we are adapted to.
Dennise
Quote:
I don't think cancer would die out. Animals can also get cancer. I think the biggest reason why cancer is such a big problem for humans is that we get older than what we are adapted to.


Yes, animals do get cancer but some e.g. sharks - shaped through eons of evolution - do not.

A agree that living longer does increase ones chances of getting it, but many develop cancer during their fertile years and so may propagate this awful disease. Environmental issues are a wild card in this as well.
Radar
The theory of evolution is the changing of creatures over time due to the survival of the fittest.

If we were deliberately changing ourselves to survive better, then maybe, but are we?
Ankhanu
Radar wrote:
The theory of evolution is the changing of creatures over time due to the survival of the fittest.

If we were deliberately changing ourselves to survive better, then maybe, but are we?

Fundamental problem here: evolution is the changing of gene frequencies in a population over time, due to a selective pressure. As you stated it, and your follow up statement, it implies that individuals change over time based on survival, which isn't true. Evolutionary processes in all cases, except artificial selection, are also not deliberate.
Bikerman
Secondary important problem: evolution acts at the genetic level not the phenotype level (ie the key factor is the gene, not the individual made from that gene). The process of natural selection is concerned with the survival of the gene, not the individual. Most of the time the two can be considered equivalent, but not always, and that way of thinking can lead to mistakes.

As one example, consider a pregnant woman. If we consider natural selection as survival of the individual, then, in any conflict between mother's survival and that of the baby, the mother's body would abort the baby to ensure survival. That is not what happens - observation does not fit theory and since this is science, this means the theory is wrong - no appeal..

When we consider it as survival of the gene then what we observe makes sense and the theory is intact.
ocalhoun
Ankhanu wrote:
Radar wrote:
The theory of evolution is the changing of creatures over time due to the survival of the fittest.

If we were deliberately changing ourselves to survive better, then maybe, but are we?

Fundamental problem here: evolution is the changing of gene frequencies in a population over time, due to a selective pressure.

...That might be an overly narrow definition, brought on because that's the only kind of evolution we're familiar with, but there could be others.*

I might broaden it by only requiring it be hereditary and relatively slowly changing over time.


*For example, self-replicating and self-improving machines could follow a very evolution-like pattern, but without genes as such. (Though I suppose you might think of their internally-stored blueprints of themselves as 'genes'.)
*Or for different example, you could have a population where a particular mutation becomes prevalent, but which has no selective pressure for or against that mutation... (something like blue eyes, maybe) Then you could have evolutionary change without the selective pressure.
Bikerman
Without the selection pressure it is difficult for me to see how a trait would spread. Generally speaking any mutation will tend to die-out over time unless it is selected for.
kelseymh
Bikerman wrote:
Without the selection pressure it is difficult for me to see how a trait would spread. Generally speaking any mutation will tend to die-out over time unless it is selected for.


I'm not sure that's true. I think a more accurate statement is that a neutral mutation will not increase in frequency unless it is selected for. Otherwise it'll just maintain at some low-to-medium rate in the population.
Bikerman
But hang on - there is surely only a chance that the mutation will be passed-on (ie the mutated gene must come from the parent with the mutation). Does it not follow that it will tend to die-out?
ocalhoun
kelseymh wrote:
Bikerman wrote:
Without the selection pressure it is difficult for me to see how a trait would spread. Generally speaking any mutation will tend to die-out over time unless it is selected for.


I'm not sure that's true. I think a more accurate statement is that a neutral mutation will not increase in frequency unless it is selected for. Otherwise it'll just maintain at some low-to-medium rate in the population.

What if it happened to be a dominant gene, while the normal, un-mutated, version was recessive?
Bikerman
Hmmm...if the gene were dominant then it would spread through that generational line. It would then depend on whether that particular line spread or not....I'm no biologist so I can't give the chances of that happening.....
Ankhanu
ocalhoun wrote:
kelseymh wrote:
Bikerman wrote:
Without the selection pressure it is difficult for me to see how a trait would spread. Generally speaking any mutation will tend to die-out over time unless it is selected for.


I'm not sure that's true. I think a more accurate statement is that a neutral mutation will not increase in frequency unless it is selected for. Otherwise it'll just maintain at some low-to-medium rate in the population.

What if it happened to be a dominant gene, while the normal, un-mutated, version was recessive?


Neutral mutations tend to not really spread unless linked to another trait. To use your eye colour example, it will propagate within the population on sheer chance alone, but if it's linked to, I dunno, genes for slightly longer tibia in a jumping species, it might be more apt to spread, even though it has no advantage or disadvantage itself. This sort of linking is well documented in many systems, and is a plague of artificial selection; select for one trait, and you get a bunch of unwanted stuff along with it Razz

Whether a neutral gene mutation is dominant or recessive is kinda moot; if it's neutral, it's neutral.
Peterssidan
If the mutation is linked to another trait that is not neutral, then the mutation can't be neutral. Am I missing something?
Ankhanu
Peterssidan wrote:
If the mutation is linked to another trait that is not neutral, then the mutation can't be neutral. Am I missing something?


No. Evolution doesn't really work in isolation, normally. Individual genes aren't really selected for or against, it's the whole package that is successful or not. That package can include mutations that are beneficial, some that are detrimental and some that have no survival/reproductive effect, or neutral. Since you get entire packages, rather than individually wrapped genes, you get a mix of the three, with benefit/detriment trade offs, and some neutrals just along for the ride.

Selection IS an active process, so neutral mutations that are in the same package as strongly beneficial or detrimental mutations will increase or decrease in frequency accordingly.
illini319
Well.. Selection is an active process but at times, it is also a stochastic one. That is to say that a neutral mutation (I'm not even sure what that means since it sure isn't technical) is only neutral within the context of non-selection. And if external conditions were to change such that it re-defines which traits of genetic diversity are advantageous versus not, then things get really interesting. In fact, such events occur all the time... It's just a matter of whether such things get passed on to the next generation. If you bought a lottery ticket with the winning numbers, but never claim it, did you really win?
Ankhanu
illini319 wrote:
... a neutral mutation (I'm not even sure what that means since it sure isn't technical) ...

A mutation is considered evolutionarily neutral if it has no impact upon fitness (i.e. survival and reproductive success). It's a change, but it does not impact the organism in any meaningful way. It is somewhat standard terminology.

illini319 wrote:
... if external conditions were to change such that it re-defines which traits of genetic diversity are advantageous versus not, then things get really interesting. In fact, such events occur all the time... It's just a matter of whether such things get passed on to the next generation.

Yup, but, evolution is, as I'm sure you recognize, a process that works in the past, rather than towards a potential future. Offspring are well suited to the environment their parents faced, not necessarily to their own or that of future generations.
illini319
Ankhanu wrote:
It's a change, but it does not impact the organism in any meaningful way. It is somewhat standard terminology.


Standard lay terminology I would agree with. Mutation is reserved for genetic changes with measurable phenotypic differences from the norm (defined as majority) that impair. Whereas polymorphisms are not mutations per se but genetic variations of non-discernible (or largely irrelevant) selective value. (e.g. Curly vs. straight hair). Neutral is too vague and implies a value (neutrality) that cannot be reliably be assessed. Maybe silent mutation is what is what is meant? In which case, these are broadly categorized as polymorphisms, not mutation.

It is a bit of splitting hairs but it is an important difference because you can only call something a mutation if you actually know what 'normal' is. Our current data of the human genome, for example, was based on about 8 people - at best. And yet still, the vast majority of the sequence is still from an old white balding guy (C. Venter). I don't know about you, but certainly I don't think bald is the new norm! (or old, white and male for that matter)

Ankhanu wrote:
Yup, but, evolution is, as I'm sure you recognize, a process that works in the past, rather than towards a potential future. Offspring are well suited to the environment their parents faced, not necessarily to their own or that of future generations.


Evolution is neither past nor future, but an incredibly slow (usually) constant - whose mechanism (genetic mutation) can only affect the future. Spontaneous mutations (as most are) do not affect past generations but have a chance to impact future generations provided its a germline mutation and that it is either positively or negatively selected for (sometime in the future, though not necessarily the very next generation). There are wrinkles to this, such as when mutations occur and if it impacts fertility or the opportunity for progeny(childhood leukemias). But these arguably are rooted in a mutation that occurred in the past generation or in utero.
Ankhanu
illini319 wrote:
Ankhanu wrote:
It's a change, but it does not impact the organism in any meaningful way. It is somewhat standard terminology.


Standard lay terminology I would agree with. Mutation is reserved for genetic changes with measurable phenotypic differences from the norm (defined as majority) that impair. Whereas polymorphisms are not mutations per se but genetic variations of non-discernible (or largely irrelevant) selective value. (e.g. Curly vs. straight hair). Neutral is too vague and implies a value (neutrality) that cannot be reliably be assessed. Maybe silent mutation is what is what is meant? In which case, these are broadly categorized as polymorphisms, not mutation.

IIRC, a silent mutation is one in which there is a change in the genotype, but no variation in phenotype (e.g. GCC being mutating to GCA still coding for alanine)? In which case, no, it is not what I meant. What I meant was a mutation, with phenotypic effect, that does not impact fitness. I.e. there is a change (anatomical or chemical), it has no discernible effect upon either survivorship or reproductive success, and is not selected for (or against) as adaptation; it is "neutral" in selection and genetic drift is more important in explaining its propagation within a population. As you mentioned, something that currently has neutral selective pressures could change in the future with changing circumstances, and can't really be predicted, but that's up to the future Wink A neutral trait MAY become common, or even come to predominance, in a population through random breeding, or it may be packaged along with a trait that IS beneficial. Likewise, it could disappear from the population for much the same reason, only change "beneficial" to "detrimental".

Maybe it wasn't used in your classes, but it was in mine.

illini319 wrote:
Ankhanu wrote:
Yup, but, evolution is, as I'm sure you recognize, a process that works in the past, rather than towards a potential future. Offspring are well suited to the environment their parents faced, not necessarily to their own or that of future generations.


Evolution is neither past nor future, but an incredibly slow (usually) constant - whose mechanism (genetic mutation) can only affect the future. Spontaneous mutations (as most are) do not affect past generations but have a chance to impact future generations provided its a germline mutation and that it is either positively or negatively selected for (sometime in the future, though not necessarily the very next generation). There are wrinkles to this, such as when mutations occur and if it impacts fertility or the opportunity for progeny(childhood leukemias). But these arguably are rooted in a mutation that occurred in the past generation or in utero.

You appear to have misunderstood; I wasn't particularly clear in my wording.
My statement was a reference to the fact that selective pressures on a parent generation result in offspring that are well suited to their parents' environment, not necessarily to their own (if there are changes in the environment). It's possible that what worked in G1, leading to a proliferation of the genes for those traits, won't be advantageous to the G2; G2 is well suited to G1's conditions; G3 is suited to G2's, and so on.
If the conditions of G2 are different than G1's, reproductive success of G1 will not predict the traits that are advantageous of G2's situation... The classic example of Darwin's finches (modulation in bill sizes as influenced by rain/drought cycles and food resource availability) nicely encapsulate this idea.

Yes, I'm using G1->G2 time lines in chat, but, yeah, we're talking longer periods in reality.
illini319
It is the term mutation I have the greatest apprehension with. What, in real terms, would a genetic variant that does manifest as an altered phenotype but has no immediate consequence nor selective pressure be other than a polymorphic trait? Independent of its predominance in a population, it would not be perceived as a mutation as there is no change in the organism's fitness in anything. If we were to use the term neutral, it would probably be more accurate to call it unperceived. As I'm sure you know, with deeper sequenciing comes the humbling appreciation of how littered we are with SNPs (or putative ones anyway), genetic variants to be sure but... less confident to be elevated to 'mutation' status unless we strip the definition of mutation down to nucleotide change. If so, then the fundamental question remains as to what one should define as wild-type since 'normal' itself has a greater tolerance for such nt changes. Genetic heterogeneity is the norm, IMO, and if anything genetic heterogeneity is the neutral 'cloud' of packaged variance that though time leads to selection. Either way to call it mutation implies a functional separation from a population - which we've just agreed it can not be if qualified as neutral.
Ankhanu
Granted, I'm not a geneticist... it's a subject I didn't pursue in any detail beyond required intro courses and associated material in other courses (and sitting in on various talks at conferences), so, yeah, I'm likely using mutation incorrectly, or too generally (my education sits at the organismal and ecological levels, not genetic/molecular/systemic). Apologies, and thanks for the slap in the right direction Wink
codegeek
...or perhaps it is all a master plan of evolution. Maybe humans were meant to become intelligent, maybe there is a grand purpose to it all. However, there is also the possibility that evolution has gone horribly wrong and we were never supposed to get smart enough to destroy ourselves and the planet in the process. In any case, I guess time will tell.
Ankhanu
codegeek wrote:
...or perhaps it is all a master plan of evolution. Maybe humans were meant to become intelligent, maybe there is a grand purpose to it all. However, there is also the possibility that evolution has gone horribly wrong and we were never supposed to get smart enough to destroy ourselves and the planet in the process. In any case, I guess time will tell.

Evolution is a blind process... nothing is meant/intended. This is a flawed premise.
mzprox
Humanity has the ability to play "gods" and also the ability to destroy herself. It's hard to say that human evolution is faster or slower novadays, there are more of us, so more chance for mutations, but actualy species is evolving/changing faster when their numbers are low, more chance for a new species to appear.

A few possible scenario for the future of humanity:

A,
-Science will prosper and eventually we will learn the method to modify ourself safely at the gemon level. And we will do it, because we can, because of power and knowledge. Sure there will be ethical protests, laws, but it can only slow it down, somewhere it will be done eventually if it hasn't been done already. (I'm working on the field btw, but only with transgenic mice Smile )

B,
-Humanity will face an apocalypse (wars over scarse resources, a pandemic, an asteroid event etc) civilization will be on downhill, humanity may have to adapt to very different conditions (different climate, pollution levels etc) so it might give a push to natural evolving

C,
-In a probably not so close future I think intelligence won't be human's only. We know our brains work like computers, it's a matter of time before artificial intelligence rises and it eventually can take the place from humans. They could be considered the next setp..

All these three at the sci-fi level right now, but they might be closer than we think.
spinout
http://www.youtube.com/watch?v=l4TKCNKaJPQ

This is my favorite subject. Genetic jumps... or??? Terraforming like the movie prometheus!
jajarvin
Evolution occurs because the living entities are trying to adapt to the conditions in which they live.
Peterssidan
jajarvin wrote:
Evolution occurs because the living entities are trying to adapt to the conditions in which they live.

Sounds like Lamarckism which has been dismissed a long time ago.
Bikerman
It is wrong on several levels.
a) It assumes entities are consciously trying to adapt. That is not necessary for evolution.
b) It misses the crucial factor of heredity - it doesn't matter what individual entities 'do' unless this is somehow transmitted to the next generation.
c) It places evolution at the level of the phenotype - the individual entity. Dawkins et al have convincingly shown that this is wrong, and that evolution should be thought of at the genotype level (cf The Selfish Gene).
scifi-real
Everything is possible, when genetics is mastered. http://scifi-real.com/playing-god-genetic-superhumans/
The question is, are we ready to play God?
Iceaxe0410
The way I view evolution is the adaptation of any life form to increase their survival rate of making it into the next generation. In other words, a life form's ability to adapt to changes in the environment to ensure survival.

Depending on how you define intelligence, it can be a part of evolution. For example, intelligence can be described as the ability to use critical thinking and analysis; to understand and come up with a solution as problems are encountered. Both can be used to adapt to changes in the environment. I wouldn't say intelligence is necessary for survival. Many lifeforms continue to live on solely on instinct or facilitated by mutual relationships with other organisms.

Of course, I do believe that intelligence can overcome the limitations of evolution which usually tends to move more slowly at least in humans. Insects, plants, and microorganisms can evolve very quickly, but many might attribute it to their shorter life cycles. Several generations occur in a shorter amount of time. That means genes and traits change more frequently over time compared to humans and other life forms.

Then of course, intelligence can have the opposite effect. Just think of how intelligence has created the implementation of guns, bombs, nuclear weapons, and machines. Those by themselves do not end life, but the people that control them. It may not be a matter of intelligence, but a matter of behavior, morals, beliefs, and emotions.

While these aren't necessarily genetics, they can be considered a form of evolution. Changing the minds and behavior of people to ensure survival is probably the quickest way to evolve for humans. Unfortunately, this can work in the opposite direction and actually cause devolution, such as war, greed, and power where people die and resources lost.

I guess one would have to ask if science and intelligence can overcome the problems of the world without destroying ourselves in the process. It's possible, I'd say, but very unlikely to happen in any of our lifetimes.
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