Question about evolution.

[3point14]

In the modern developed world everyone views procreation as a right. There is, therefore, no natural selection. In addition medical advances have led to us managing to keep in the gene pool those individuals who otherwise would have left it.

We seem to have evolved over the past years/centuries/millenia to be taller, better looking and, perhaps most crucially, smarter. Or at least better able to manipulate our environment.

There seem to be no selection pressures at any level of modern western society any more so have we stopped evolving?

If we have, what effect will this have on future generations? Are we storing up stupidity and illness for our decendants?

[drkitten]

In the modern developed world everyone views procreation as a right. There is, therefore, no natural selection. In addition medical advances have led to us managing to keep in the gene pool those individuals who otherwise would have left it.

We seem to have evolved over the past years/centuries/millenia to be taller, better looking and, perhaps most crucially, smarter. Or at least better able to manipulate our environment.

There seem to be no selection pressures at any level of modern western society any more so have we stopped evolving?

You contradict yourself.

As you point out, we seem to have evolved to be taller, better looking, and smarter. These trends
continue. Regardless of whether or not you view procreation as a "right," unless you're really really good at Applied Parthenogenesis, you still have the mate-selection problem. If you're dumb and ugly, you're going to have a much harder time getting laid -- and thus does humanity evolve for better-looking and smart.

And unless your doctor is much, much better than mine, there are still an awfully large number of people out there leaving the gene pool prematurely. Including people leaving for reasons that are technically preventable, but the people involved are either too poor or too dumb to be able to take advantage of them. Which again, one way that humanity evolves for smart.

So the simplest answer is that there still are selection pressures; they're simply different ones than we had before.

[Hawk one]

I think the main mistake is to think that there is some sort of "higher" target to evolve into. It isn't, it just happens. And just because there used to be one kind of pressure that is now gone, that doesn't mean all the other pressures from the world is gone. So, we keep on evolving, every single generation,only we now have different kind of pressures than we had in the past.

And make no mistake. the Western society do have lots of pressures. Some of them are preventable, some are harder to deal with because you got a poor hand at life from the start, both in your own body as well as what sort of upbringing you had.

[cyborg]

The losers don't get a say.

That's about as simple as it gets.

[VonNeumann]

We seem to have evolved over the past years/centuries/millenia to be taller, better looking and, perhaps most crucially, smarter.

Surely you are joking?

There is enough variation in the human genome for ugly/pretty, smart/challenged, tall/short ... without invoking "evolution".

[MRC_Hans]

Yes, the present variation we see in humanity, within historical times, can hardly be termed evolution. We are pretty much the same creatures as our Cro Magnon ancestors 100,000 years ago.

Hans

[3point14]

Woah! It's not like I was advocating eugenics or anything! :)

I'm sure, as has been pointed out, that the OP is far from perfect. I would never claim to be any sort of expert on evolution (or indeed on anything) I was just inviting speculation as to how modern (western) society would influence evolution in Homo Sapiens.

I figure that 'the right to breed' seems pretty universal.

Regardless of how successful or otherwise one is in life it's not going to stop one having and successfully raising children if the desire is there. If everyone that wants to can breed and by far the majority of those offspring survive, then surely that removes a whole raft of selection pressures and would have a large effect on the gene pool going forward?

Or not? As ever, I reserve the right to be wrong.

[MRC_Hans]

Well, on that, it is possible that we are putting natural selection out of work. One conspicuous area is fertility. In a natural setting, low fertility would be one trait likely to be weeded out rather quickly, but since we are able to help people with even very low fertility to be come parents, such a trait can now spread (assuming that it is, at least partly, genetic).

Eugenics is nasty word, mainly due to it's historical implications, but sooner or later, humanitiy may be forced to take it's evolution in it's own hands. Hopefully, that will be by genetic engineering, and not by weeding out any undesirables.

Hans

[drkitten]

If everyone that wants to can breed and by far the majority of those offspring survive, then surely that removes a whole raft of selection pressures and would have a large effect on the gene pool going forward?

Yeah, well, when you start with a false assumption, you can conclude anything you like. If I have a unicorn in my dresser, then Angelina Jolie is the Queen of Canada.

In this case, the false assumption is that "everyone that wants to can breed." You're also implicitly assuming that "everyone who can breed can breed as much as they like", which is also false.

[3point14]

Yeah, well, when you start with a false assumption, you can conclude anything you like. If I have a unicorn in my dresser, then Angelina Jolie is the Queen of Canada.

In this case, the false assumption is that "everyone that wants to can breed." You're also implicitly assuming that "everyone who can breed can breed as much as they like", which is also false.

Good mood today? I wasn't really trying put my assumptions up as too correct. I was kind of hoping that my tone might indicate that. Please feel free to educate me on matters that I (freely admit I) lack knowledge in, but go easy on the sarcasm?

[SomeGuy]

First of all, I am pretty certain that the increase in length/attractiveness/smarts is fully due to better food and better medical care.

Better food is obvious, but also better medical care which means that kids over the 16-19 years they do their growing up in, spend less days being sick.

I disagree with MRC_Hans about the (eventual) necessity of human driven human evolution. I don't think however that at this point it's appropiate to hold that debate which can hardly be based at currently available facts.

I think at the very least we can agree that if it will ever be necessary, it will not be in our time.

[Loss Leader]

In the modern developed world everyone views procreation as a right.


This is the only portion of your post with which I unreservedly agree. Procreation is, legally, a right that is almost impossible to curtail.


Are we storing up stupidity and illness for our decendants?


I would think that the absolute worst we're doing is preserving stupidity and illness at current rates. Since many factors affecting stupidity and illness may be environmental, it's possible that we could reduce both without rewriting our DNA at all.

[Big Les]

I agree that the assertion that we are evolving towards taller and better looking is flawed. "Ugly" people are still procreating with each other, if not with "better looking" ones (and some of us are managing it!). There's plenty of variation in between those subjective extremes. How you would determine that we are on average more attractive than centuries/millennia past, I don't know, but the average height of a man has changed by a few inches in 500 years or so, which can only be down to improved nutrition and healthcare.

In fact I'd tend to agree that the traditional ("natural" if you like) selection pressures have been removed for those reasons, as well as a lack of natural predators, and so on. However as others have said a whole new, more complex set of pressures will be taking their place and having effects upon our physiology the outcome of which we can't predict.

Are there really any changes that we can point to between Early Modern and present-day Homo Sapiens Sapiens? Is 40-100,000 years of the pressures we've had enough to have had measurable effect?

[Jimbo07]

Are we storing up stupidity and illness for our decendants?

See Idiocracy with Luke Wilson!

:D

[Taffer]

In the modern developed world everyone views procreation as a right. There is, therefore, no natural selection. In addition medical advances have led to us managing to keep in the gene pool those individuals who otherwise would have left it.

We seem to have evolved over the past years/centuries/millenia to be taller, better looking and, perhaps most crucially, smarter. Or at least better able to manipulate our environment.

There seem to be no selection pressures at any level of modern western society any more so have we stopped evolving?

If we have, what effect will this have on future generations? Are we storing up stupidity and illness for our decendants?

The important thing to remember, is, natural selection always occurs. Everywhere. Always. We cannot stop it, because doing so will produce other pressures. Any human-generated pressures are still "natural".

No, we have not stopped evolving. No, we will not ever stop evolving unless all variation within the human population reaches 0 (or close to it).

[Taffer]

Yes, the present variation we see in humanity, within historical times, can hardly be termed evolution. We are pretty much the same creatures as our Cro Magnon ancestors 100,000 years ago.

Hans

Well... that depends. Are the allele frequences different now then they were 100,000 years ago?

[drkitten]

How you would determine that we are on average more attractive than centuries/millennia past, I don't know,

You don't need to. Sexual selection is one of those wierd things that doesn't necessarily make sense to an outsider, but it's well-documented. I don't find peacocks (or scissor-tailed flycatchers (http://www.bioone.org/perlserv/?request=get-abstract&doi=10.1642%2F0004-8038(2001)118%5B0167%3ASSATLD%5D2.0.CO%3B2)) with particularly long tails to be "more attractive than centuries/millenia past," but I'm not the one that the peacocks were trying to impress. Similarly, a female Neanderthal might find the absence of brow ridges hideous --- but I'm neither a female Neanderthal nora male one.

Physical attractiveness -- whatever it means -- has been shown to be a positive survival trait in a lot of ways in modern society. It's also largely heritable; good-looking parents produce good-looking children. And it's also well-documented (as well as being generally plausible) that it's an advantage when it comes to getting a mate in the first place to be good-looking. (Even to the extent of overriding age! (http://www.newscientist.com/article.ns?id=dn940))



Are there really any changes that we can point to between Early Modern and present-day Homo Sapiens Sapiens? Is 40-100,000 years of the pressures we've had enough to have had measurable effect?

Not large-scale physical changes. 100,000 years is a very short time for gross morphological change, regardless of whether or not you're talking about man, monkeys, or mice. There are a lot of well-documented minor changes, however, many of which are clearly a result of cultural selection. For example, lactose tolerance is a relatively recent phenomenon, widespread (for the most part) only in populations with a history of adult dairy consumption. Humans have also co-evolved with a number of disease organisms such as smallpox and syphillis.

Ten thousand years ago, we were breeding children for lactose tolerance, because children who were lactose intolerant didn't do as well. Today, children who are phenylalanine intolerant don't do as well. Although it's possible to raise such a child on an aspartame-free diet, it's not a trivial task, and requires medical attention beyond the 'norm' (especially beyond the 'norm' that a low-income child can typically get). I expect that phenylalanine intolerance will be much less common five hundred years from now than it is now, unless we drop aspartame out of our diets.

[ReligionStudent]

Woah! It's not like I was advocating eugenics or anything! :)

I'm sure, as has been pointed out, that the OP is far from perfect. I would never claim to be any sort of expert on evolution (or indeed on anything) I was just inviting speculation as to how modern (western) society would influence evolution in Homo Sapiens.

I figure that 'the right to breed' seems pretty universal.

Regardless of how successful or otherwise one is in life it's not going to stop one having and successfully raising children if the desire is there. If everyone that wants to can breed and by far the majority of those offspring survive, then surely that removes a whole raft of selection pressures and would have a large effect on the gene pool going forward?

Or not? As ever, I reserve the right to be wrong.

The fact is that not everyone has the right to reproduction. People of diminished mental faculties, from disease, or genetics, often are not considered able to consent and are thus do not have this right. Additionally, and possibly most important, no one has yet given the dead the right to reproduction. People who die young, either due to disease, accident, or genetic conditions, are unable to reproduce, and are thus selected against.

Additionally, you overlook the many studies that have shown sexual selection in humans, tied to looks, money, and other complex variables. So, even if everyone were allowed to reproduce, not everyone will be able to.

[Big Al]

Are there really any changes that we can point to between Early Modern and present-day Homo Sapiens Sapiens? Is 40-100,000 years of the pressures we've had enough to have had measurable effect?

I'll bet the average Cro-Magnon or Neanderthal could survive in our time a lot better than the average modern could survive in theirs.

All I will ask is that who is more likely to outbreed whom: a lean, dedicated athlete who lives only to win, or an unemployed couch potato with nothing to do?

[Big Les]

The latter, I'd have thought.

[becomingagodo]

All I will ask is that who is more likely to outbreed whom: a lean, dedicated athlete who lives only to win, or an unemployed couch potato with nothing to do?
Its not that simple.

Well, the people who have the most children are rapist and chinese, so I guess their is a selective pressure to be chinese or a rapist. Note: I got the birthrate thing from a person talking about evolution, it was from a lecture so I don't know if it right or wrong. I wonder if their is a evolutionary reason I am more attracted to oritental looking people.

Although having poor traits in your gene pool is not good nor bad, it is a commen mistake to think that danagerous traits are bad in evolutionary terms, proberly because of the survival of the fittest statement being overused. http://www.amazon.com/Survival-Sickest-Medical-Maverick-Discovers/dp/0060889659 survival of the sickest.

In the future evolution would proberly become more blurred, as cosmetic surgery and computer enhancement of humans would proberly become normal. So looks and intelligence would proberly become removed from the evolution selective pressure.

[Big Al]

Well, the people who have the most children are rapist and chinese, so I guess their is a selective pressure to be chinese or a rapist.

I would have thought only a very small percentage of very pro-life women would choose to carry a rape baby to term. And the Chinese government is finally trying to put the brakes on their birthrate.




If there is, I have the same genes. I find Oriental women very attractive.

http://www.amazon.com/Survival-Sickest-Medical-Maverick-Discovers/dp/0060889659[/URL] survival of the sickest.

In the future evolution would proberly become more blurred, as cosmetic surgery and computer enhancement of humans would proberly become normal. So looks and intelligence would proberly become removed from the evolution selective pressure.

Perceived poor traits can only gain an upper hand if:


They are advantageous or neutral in the heterozygous state (a single copy of the sickle-cell gene does not make the bearer ill, but provides malaria resistance. Two copies are required for the sickle-cell syndrome)
They do not prevent survival to child-bearing age
They don't distort birthrates (there are genes that can)
The gene pool is restrictedYou make a good point about looks and plastic surgery. However, one could say that only the wealthy can afford plastic surgery, and that such people tend to have smaller families (pushed to keep working, keep making films, play sports etc.) The state-subsidised couch potato will still tend to win out.

A small minority may choose to delay childbirth until later years (good for editing out lethal genes) but the teenage birthrate is rising (bad for lethal gene proliferation). What's more, medicine ensures that the vast majority of babies survive, regardless of many formerly fatal genetic conditions like hemophilia, cystic fibrosis, osteogenesis imperfecta, etc. This can only ensure that the genes can proliferate.

I think the selection pressures are on hold at the moment, because we live in this benign, artificial coccoon. Nonetheless, we're saving up lethal genes. If civilisation and technology ever did collapse, I think members of technologically-advanced nations could well fall prey to the accumulated baggage of lethal genes, failing to maintain a viable population.

[Paul C. Anagnostopoulos]

In the modern developed world everyone views procreation as a right. There is, therefore, no natural selection.
Say what?


Well, the people who have the most children are rapist and chinese, so I guess their is a selective pressure to be chinese or a rapist.
Say what?

~~ Paul

[TX50]

So humans will evolve to be good-looking, intelligent, Chinese rapists.

[Dogdoctor]

Here is my take, inteligent people are having fewer kids so we will end up being dumber due to lower IQ people passing their genes on more often.

[Loss Leader]

Here is my take, inteligent people are having fewer kids so we will end up being dumber due to lower IQ people passing their genes on more often.


I don't think "inteligent" people are having fewer children, I think "richer" people are having fewer children. Maybe within a fairly well-off country like the US, intelligence and wealth might be corelated. But there are billions of people on this planet who have never gotten the chance to demonstrate or develop their intelligence.

Also, we are presuming that intelligence is genetic. Much of it may be due to a healthy gestational and early childhood environment.

Grab a random sample of dirt poor people from rural China or Bangladesh, transplant them to Sunnyvale, California and give them nice incomes and lots and lots of education and then wait two generations.

I would bet the intelligence of their grandchildren and the intelligence of the native Californians is identical.

Except, of course, the surfers. But they will have moved south to San Diego long ago. You can't surf in a bay.

[Meadmaker]

My wife and I went through IVF when trying to have a second child. At some point it was suggested that donor eggs be used, and in discussing it with doctors, they pointed out that although we couldn't meet the women involved. we could see vital statistics such as height, body measurements, education levels, and all sorts of things that were indicators of high quality.

I've read that highly desirable women (i.e. documentably smart, athletic, healthy, or beautiful) can sell their eggs for top dollar.

Of course, when shopping for sperm donors, no one takes any old sperm from any guy who got paid to...donate. You learn the vital stats so that at least half the genes can be guaranteed to come from good stock.

It seems that high quality genes are finding ways to get where they need, even in these days when so many possessors of them don't want the trouble of actually being parents. Natural selection works in strange and mysterious ways,

[epepke]

Oh, foo! There are a lot of things that we have evolved in fairly recent times, less than 100,000 years. About half a dozen ways of resisting malaria, including favism, which couldn't have evolved before agriculture. Adaptations amongst northern Europeans to keep producing lactase after weaning. Increased ability to metabolize alcohol amongst Germanic types.

As long as there is any differential reproductive rate, which of course there is, we will continue to evolve. In a few thousand years, we may have evolved a susceptibility toward Catholicism or a resistance to HIV or greater stupidity (stupid people seem to breed faster).

[The Great Hairy One]

In the modern developed world everyone views procreation as a right. There is, therefore, no natural selection. In addition medical advances have led to us managing to keep in the gene pool those individuals who otherwise would have left it.

We seem to have evolved over the past years/centuries/millenia to be taller, better looking and, perhaps most crucially, smarter. Or at least better able to manipulate our environment.

There seem to be no selection pressures at any level of modern western society any more so have we stopped evolving?

If we have, what effect will this have on future generations? Are we storing up stupidity and illness for our decendants?


I'd dispute that we've "evolved" to become taller, smarter or better looking than our recent ancestors. Exposure to better food, better living conditions, less environmental toxins (no lead pipes, etc.) and better education would account for the majority of the increases in those areas. Remember that phenotype is not wholly dependant upon genotype (let me know if you need those terms explained).

In the modern developed world everyone views procreation as a right. There is, therefore, no natural selection.


This is quite wrong. Disease, environmental changes, allele frequencies, genetic drift - all of these are still present and are not dependant upon whether or not we have the right to procreate.

Furthermore, please understand that us geneticists only consider evolution to work on populations not individuals. Thus you have to examine the population as a whole, not as a sum of its parts. This is a very important distinction.

As to predicting what humans will look like in 10,000 years - our technology will easily overtake the natural processes of evolution within the next few hundred years. I predict that within the next three to four generations, parents will be gene-tailoring their offspring, with the aim of including specifically desired gene mixes. I suspect that we'll pretty much be controlling our own evolution shortly.

Yes, the present variation we see in humanity, within historical times, can hardly be termed evolution. We are pretty much the same creatures as our Cro Magnon ancestors 100,000 years ago.



Not quite true. Recent human evolution includes being able to digest milk as an adult (See: http://www.nytimes.com/2006/12/10/science/10cnd-evolve.html?ex=1184817600&en=18dddefec3102d5c&ei=5070). That's a currently known example, I am sure that if I dug a bit more that I could find others.

Cheers,
TGHO

[The Great Hairy One]

I'll bet the average Cro-Magnon or Neanderthal could survive in our time a lot better than the average modern could survive in theirs.



Note so. Due to recent - and I mean within the last 10,000 years - modern humans have developed a resistance to a great number of serious diseases which would knock the Cro Magnon or Neanderthal dead very, very quickly.

Read "Guns, Germs and Steel" by Jarred Diamond for more information around this.

Here is my take, inteligent people are having fewer kids so we will end up being dumber due to lower IQ people passing their genes on more often.


IQ is a quantitative genetic trait. This means that many, many genes make up the overall "intelligence" of the end organism. Due to the allele frequencies within a population, it's really impossible (at our current level of understanding) to predict how "smart" a kid will be when produced by parents A & B. Furthermore, due to random allele mixing during sexual reproduction, kid 1 will have a markedly varied level of "smart" than kid 2, kid, 3, and so on.

Cheers,
TGHO

[Corsair 115]

Here is my take, inteligent people are having fewer kids so we will end up being dumber due to lower IQ people passing their genes on more often.See C.M. Kornbluth's The Marching Morons for a science-fiction short story which uses that idea as a backdrop.

[PixyMisa]

Here is my take, inteligent people are having fewer kids so we will end up being dumber due to lower IQ people passing their genes on more often.
However, IQ scores have been rising steadily ever since IQ testing was introduced. (This is called the Flynn effect, and it's true all over the world.)

[Taffer]

Furthermore, please understand that us geneticists only consider evolution to work on populations not individuals. Thus you have to examine the population as a whole, not as a sum of its parts. This is a very important distinction.

Ooh, what field of genetics?

[The Great Hairy One]

Ooh, what field of genetics?


I used to study Drosophila stress resistance, and was aiming to do my PhD in the genetic basis of aging, but gave up science for a career in IT. I've not worked in science since 1994, but keep up to date by reading journals and chatting with friends from back then (who are now in research and lecturing).

I call myself a geneticist because I have a degree majoring in genetic engineering and evolution studies.

Cheers,
TGHO

[Art Vandelay]

If everyone that wants to can breed and by far the majority of those offspring survive, then surely that removes a whole raft of selection pressures and would have a large effect on the gene pool going forward?"Forward" implies teleology.

but since we are able to help people with even very low fertility to be come parents, such a trait can now spread (assuming that it is, at least partly, genetic).Why would it spread? Removing pressures against, and providing pressures in favor, are two entirely different things.

Eugenics is nasty word, mainly due to it's historical implications,"its"

In this case, the false assumption is that "everyone that wants to can breed." You're also implicitly assuming that "everyone who can breed can breed as much as they like", which is also false.For the most part, that is true. Especially for women. A woman determined to have children can pick up guys, then put the kids up for adoption.

I'll bet the average Cro-Magnon or Neanderthal could survive in our time a lot better than the average modern could survive in theirs.I think that speaks more to our social safety net than our relative survival abilities.

All I will ask is that who is more likely to outbreed whom: a lean, dedicated athlete who lives only to win, or an unemployed couch potato with nothing to do?Anyone secure enough to be a couch potato is well able to reproduce. Someone who is constantly exhausted (an "athlete" is misleading, as actual athletes are careful to not overtax their bodies) is less likely to reproduce. In fact, especially strenuous activity often causes women to stop having periods. And in ancient times, injuries and diseases were rife.

I would have thought only a very small percentage of very pro-life women would choose to carry a rape baby to term.Why? You really think that most women would be willing to kill their children merely because of how they were conceived?

Except, of course, the surfers. But they will have moved south to San Diego long ago. You can't surf in a bay.Santa Cruz is closer.

[SomeGuy]

I would have thought only a very small percentage of very pro-life women would choose to carry a rape baby to term. And the Chinese government is finally trying to put the brakes on their birthrate.




If there is, I have the same genes. I find Oriental women very attractive.



In the future evolution would proberly become more blurred, as cosmetic surgery and computer enhancement of humans would proberly become normal. So looks and intelligence would proberly become removed from the evolution selective pressure.

Perceived poor traits can only gain an upper hand if:


They are advantageous or neutral in the heterozygous state (a single copy of the sickle-cell gene does not make the bearer ill, but provides malaria resistance. Two copies are required for the sickle-cell syndrome)
They do not prevent survival to child-bearing age
They don't distort birthrates (there are genes that can)
The gene pool is restrictedYou make a good point about looks and plastic surgery. However, one could say that only the wealthy can afford plastic surgery, and that such people tend to have smaller families (pushed to keep working, keep making films, play sports etc.) The state-subsidised couch potato will still tend to win out.

A small minority may choose to delay childbirth until later years (good for editing out lethal genes) but the teenage birthrate is rising (bad for lethal gene proliferation). What's more, medicine ensures that the vast majority of babies survive, regardless of many formerly fatal genetic conditions like hemophilia, cystic fibrosis, osteogenesis imperfecta, etc. This can only ensure that the genes can proliferate.

I think the selection pressures are on hold at the moment, because we live in this benign, artificial coccoon. Nonetheless, we're saving up lethal genes. If civilisation and technology ever did collapse, I think members of technologically-advanced nations could well fall prey to the accumulated baggage of lethal genes, failing to maintain a viable population.[/QUOTE]

Alternatively civilisation and technology collapse and new diseases occur and the humans that best adapt are those from the technologically advanced nations due to their greater genetic variance.

[Taffer]

I used to study Drosophila stress resistance, and was aiming to do my PhD in the genetic basis of aging, but gave up science for a career in IT. I've not worked in science since 1994, but keep up to date by reading journals and chatting with friends from back then (who are now in research and lecturing).

I call myself a geneticist because I have a degree majoring in genetic engineering and evolution studies.

Cheers,
TGHO

Oh, neat! I have a BSc in Genetics, and I'm currently doing graduate studies in Phylogenetics and Evolutionary genetics.

[qayak]

In fact, especially strenuous activity often causes women to stop having periods.

Not strenuous activity, it is when their body fat drops below a certain percentage. This is not just especially strenuous activity, it is very strenuous activity over a prolonged period of time. Common to marathon and other long distance runners. It maybe strenuous to carry a heavy box up a flight of stairs but that won't cause a woman to stop having a period. :D

[The Great Hairy One]

Oh, neat! I have a BSc in Genetics, and I'm currently doing graduate studies in Phylogenetics and Evolutionary genetics.


Your knowledge would be much more up-to-date than mine, then! Whilst I was very much heavily into the science when I was studying and working in it back in 88-94, I consciously avoided it for several years after I started work in IT.

Phylogenetics is a great field. Lots of stuff there worth looking at!

Cheers,
TGHO

[Dogdoctor]

Intelligence may be going up due to better education, better diet, overall a better environment for the child but intelligent people from my perspective seem to be generally busy people and less intelligent people have much more time to spend raising offspring. Intelligent people also realize there is a population problem and wouldn't have lots of kids for that reason too. I am pretty sure that on the average highly intelligent people have less kids than lower IQ people. Even if there is more effect of environment on intelligence there is still likely an inherited basis and that will gradually dwindle away due to less intelligent people having more kids who survive. How many geniuses have 12 children?

[wollery]

Well, the people who have the most children are rapist and chinese, so I guess their is a selective pressure to be chinese or a rapist.

I would have thought only a very small percentage of very pro-life women would choose to carry a rape baby to term. And the Chinese government is finally trying to put the brakes on their birthrate. I have no idea what the heck the rapist argument is about. rape has little or nothing to do with procreation, and most babies born to rape victims are either abandoned or aborted.

As for the Chinese, they've been putting the brakes on their population for about 30 years, and highly successfully too. Which is why most of my friends have no siblings, and have only one child themselves. It's called the "one child policy" and has curbed the Chinese population growth rate so efficiently that it's heading rapidly towards zero, and is far below that of the US.

The country with the fastest growing population is Liberia. In fact, Africa's population is growing much faster than Asia's.

http://www.globalhealthfacts.org/topic.jsp?i=81

The birth rate in China is the 157th highest in the world (Africa having the 12 highest rated countries)!

http://www.globalhealthfacts.org/topic.jsp?i=69

This is largely due to China having the second highest contraceptive use rate in the world.

http://www.globalhealthfacts.org/topic.jsp?i=72

[3point14]

I'd dispute that we've "evolved" to become taller, smarter or better looking than our recent ancestors. Exposure to better food, better living conditions, less environmental toxins (no lead pipes, etc.) and better education would account for the majority of the increases in those areas. Remember that phenotype is not wholly dependant upon genotype (let me know if you need those terms explained).


No, phenotype and genotype I can do. Spelling them consistently, however...



This is quite wrong. Disease, environmental changes, allele frequencies, genetic drift - all of these are still present and are not dependant upon whether or not we have the right to procreate.

Furthermore, please understand that us geneticists only consider evolution to work on populations not individuals. Thus you have to examine the population as a whole, not as a sum of its parts. This is a very important distinction.


Thank you for that, something I know (or have known) but tend to forget to consider.



As to predicting what humans will look like in 10,000 years - our technology will easily overtake the natural processes of evolution within the next few hundred years. I predict that within the next three to four generations, parents will be gene-tailoring their offspring, with the aim of including specifically desired gene mixes. I suspect that we'll pretty much be controlling our own evolution shortly.


That scares me slightly. Maybe it's just regular old fear of the unknown.



Not quite true. Recent human evolution includes being able to digest milk as an adult (See: http://www.nytimes.com/2006/12/10/science/10cnd-evolve.html?ex=1184817600&en=18dddefec3102d5c&ei=5070). That's a currently known example, I am sure that if I dug a bit more that I could find others.

Cheers,
TGHO

Thanks.

"its"


Thanks. One of my pet peeves and I go and do it myself.

[Big Al]

Note so. Due to recent - and I mean within the last 10,000 years - modern humans have developed a resistance to a great number of serious diseases which would knock the Cro Magnon or Neanderthal dead very, very quickly.

I presume you meant "Not so", TGHO ;)

Can you give some examples? I've had shots against TB, yellow fever, dengue fever, smallpox, polio, filiariasis, malaria and god knows what else. Take those away and send me to the Sudan, and get ready to count my life expectancy in weeks if not days.

We may have gained some level of immunity to some diseases, such as plague, at some time, but have almost certainly lost it now. The fact is that, in the post-antibiotic/aseptic era, the selection pressures for immunity have been greatly reduced if not eliminated.

What is to say that Cro-Magnon or Neanderthal were immune to diseases we've long forgotten? At least in the modern era they'd have a good chance of being cured of modern ailments.

[Belz...]

Surely you are joking?

There is enough variation in the human genome for ugly/pretty, smart/challenged, tall/short ... without invoking "evolution".

Uh-huh. Where do you think those "variations" come from ?

[drkitten]

Can you give some examples? I've had shots against TB, yellow fever, dengue fever, smallpox, polio, filiariasis, malaria and god knows what else. Take those away and send me to the Sudan, and get ready to count my life expectancy in weeks if not days.

And, yet, somehow, the Sudanese -- all forty million of them -- have life expectancies measured in decades.


We may have gained some level of immunity to some diseases, such as plague, at some time, but have almost certainly lost it now.

No. It takes a lot longer than a few hundred years for widespread resistance to disappear from the genome. Just as a simple example -- how many children do you know that die of measles? The death rate from measles has been documented among Native Americans at well over 50% -- because they didn't have any resistant at all.

Plague is actually another good example. The simple fact is that we have not eradicated plague, but simply gotten sufficiently resistant to it that it no longer spreads quickly. There are still something like 100 cases a year in the USA -- but no one catches the plague, even in the pneumonic variant which is spread directly from person to person. The fact is, we've developed resistance to infection by that particular bug, enough to reduce it from a global killer to a nuisance.

The "Spanish flu" that killed more people in 1918 than the First World War is another good example; that particular variant is still around, but it's so harmless that they don't even bother including it in the anti-flu cocktail any more.

Similarly, look up the death rates and infection rates for syphillils and how we've co-evolved with the spirochete since the 1500s.



The fact is that, in the post-antibiotic/aseptic era, the selection pressures for immunity have been greatly reduced if not eliminated.

This is -- not to put too fine a point on it -- simply incorrect.

[supercorgi]

Adaptations amongst northern Europeans to keep producing lactase after weaning. Increased ability to metabolize alcohol amongst Germanic types.

Thanks ancestors! Because of you I can enjoy both cheese and beer! :D

[The Great Hairy One]

I presume you meant "Not so", TGHO ;)


Just proving that even I am not perfect - a shock, I know. :p


Can you give some examples? I've had shots against TB, yellow fever, dengue fever, smallpox, polio, filiariasis, malaria and god knows what else. Take those away and send me to the Sudan, and get ready to count my life expectancy in weeks if not days.


Not quite. There are a great number of diseases which dramatically affected native populations when they first encountered Europeans. Smallpox was even used as a biological weapon in Australia in the early 1800's, well before immunisation was even understood.

Generally, my expectations would be that a modern human would have a much greater chance of resisting or surviving modern diseases than a Cro-Magnon or Neanderthal.

We may have gained some level of immunity to some diseases, such as plague, at some time, but have almost certainly lost it now. The fact is that, in the post-antibiotic/aseptic era, the selection pressures for immunity have been greatly reduced if not eliminated.


This is simply not true. Firstly, we've not lost immunity to diseases. Those diseases still exist within the environment, such as Black Plague. One of the main reasons Black Plague really isn't a threat anymore is not because we're immunised to it, but rather that the survivors of the outbreaks in the past have passed on their immunity to current generations. That's just one example, there are many others. Measles, mumps, smallpox, chicken pox, influenza, all sorts of fevers, etc., etc. are other examples.

Secondly, selection pressures for immunity have certainly not been reduced or eliminated. Antibiotic resistant bacteria are a major threat today, and the evolutionary pressure on bacteria and virii is certainly still present. We get a new strain of influenza nearly every year. There's still dozens of diseases, like malaria, which we just can not control.

What is to say that Cro-Magnon or Neanderthal were immune to diseases we've long forgotten? At least in the modern era they'd have a good chance of being cured of modern ailments.


It's quite possible that modern medicine could keep a Cro-Magnon or Neanderthal alive if they contracted a modern disease. However, the risk of them dying most certainly would be higher, because their immune system would not have the same level of reaction to the disease as ours would.

Have a read of examples in history - Europeans wiping out huge populations in North and South America and Australia via introducing diseases the natives had either never encountered or had never developed a resistance to. A Cro-Magnon or Neanderthal would fair about as well as an American Indian, Incan, Aztec or Australian Aboriginal in these cases.

Cheers,
TGHO

[ReligionStudent]

I'll bet the average Cro-Magnon or Neanderthal could survive in our time a lot better than the average modern could survive in theirs.

All I will ask is that who is more likely to outbreed whom: a lean, dedicated athlete who lives only to win, or an unemployed couch potato with nothing to do?

I think part of the point is that the person from today would have firearms, antibiotics, etc, and the reason they might be fat is better nutrition and less physical exertion and stress.

[ReligionStudent]

I presume you meant "Not so", TGHO ;)

Can you give some examples? I've had shots against TB, yellow fever, dengue fever, smallpox, polio, filiariasis, malaria and god knows what else. Take those away and send me to the Sudan, and get ready to count my life expectancy in weeks if not days.

We may have gained some level of immunity to some diseases, such as plague, at some time, but have almost certainly lost it now. The fact is that, in the post-antibiotic/aseptic era, the selection pressures for immunity have been greatly reduced if not eliminated.

What is to say that Cro-Magnon or Neanderthal were immune to diseases we've long forgotten? At least in the modern era they'd have a good chance of being cured of modern ailments.

This is a big part of Diamond's Guns Germs and Steel. His theory is that due to having domestic animals Europeans have developed immunity or resistance to more diseases than non-Europoeans and were able to destroy cultures they came into contact with through these diseases while surviving them easily.

[skeptigirl]

In the modern developed world everyone views procreation as a right. There is, therefore, no natural selection. In addition medical advances have led to us managing to keep in the gene pool those individuals who otherwise would have left it.

We seem to have evolved over the past years/centuries/millenia to be taller, better looking and, perhaps most crucially, smarter. Or at least better able to manipulate our environment.

There seem to be no selection pressures at any level of modern western society any more so have we stopped evolving?

If we have, what effect will this have on future generations? Are we storing up stupidity and illness for our decendants?I haven't read the two pages yet so this is probably redundant. It's a myth that we are not still evolving. The time scale which evolution takes place is slow in organisms which reproduce as slowly as we do. So you just can't see much happening. If you look back at humans from 10,000 years ago, we are actually noticeably different

The second myth is that selection is all good (similarly evolution deniers try to claim all mutations are bad). So we keep a diabetic alive, but that included the intelligence of someone to do so. So you get both at the same time. And as highly educated, perhaps most intelligent people have fewer and fewer kids, along comes something like pandemic flu and those with fewer healthier kids are selected over those with many, less healthy ones. Perhaps even the more intelligent persons who simply wash their hands are at an advantage.

Also, keeping people with genetic defects alive is analogous to tool use. Perhaps the lion is genetically at an advantage except we have the intelligence to make guns. Insulin is just another kind of tool.

[skeptigirl]

I presume you meant "Not so", TGHO ;)

Can you give some examples? I've had shots against TB, yellow fever, dengue fever, smallpox, polio, filiariasis, malaria and god knows what else. Take those away and send me to the Sudan, and get ready to count my life expectancy in weeks if not days.Nitpick as long as you opened the door, unless that was BCG vaccine, the "shot" against TB would have been a screening test for inactive TB, not a shot against TB. And would that we had a malaria "shot" it would save a lot of people. There are prophylactic anti-parasitics for malaria.

As of 2005 when CDC last updated this page, (http://www.cdc.gov/NCIDOD/DVBID/DENGUE/) No dengue vaccine is available. Recently, however, attenuated candidate vaccine viruses have been developed. Efficacy trials in human volunteers have yet to be initiated. Research is also being conducted to develop second-generation recombinant vaccine viruses. Therefore, an effective dengue vaccine for public use will not be available for 5 to 10 years.

The last routine smallpox vaccines for travel to the Sudan was at least 20 years ago or more, so I assume you are talking a while ago? In which case you likely got oral polio vaccine. However, were you an adult who never had oral polio vaccine as a child, you may have had the killed injectable form.

And as for filariasis, again there is no preventative "shot". It is prevented by avoiding mosquito bites in endemic areas. If you had contracted it, you'd be getting an annual dose of medication for as long as the adult worms remained alive, (I have no clue how long that is but I'm sure you could find it on the Web). The medicine keeps the larvae from destroying your body but doesn't kill the adult worms.

Again from CDC: (http://www.cdc.gov/NCIDOD/DPD/parasites/lymphaticfilariasis/factsht_lymphatic_filar.htm)Who is at risk for infection?

Repeated mosquito bites over several months to years are needed to get lymphatic filariasis. People living for a long time in tropical or sub-tropical areas where the disease is common are at the greatest risk for infection. Short-term tourists have a very low risk. An infection will show up on a blood test.


We may have gained some level of immunity to some diseases, such as plague, at some time, but have almost certainly lost it now. The fact is that, in the post-antibiotic/aseptic era, the selection pressures for immunity have been greatly reduced if not eliminated.Antibiotics cure plague. Natural selection resulting in amplified genetic mutations offering immunity or partial immunity to plague are not particularly widespread though at least one genetic change has been identified that may offer protection. There is nothing "de-selecting" it. So the idea of lost genetic immunity is wrong. You are probably confusing acquired immunity such as survivors having antibodies against repeat infections. Newborns have a few of these antibodies from Mom for a few months but otherwise they are not genetically passed on.

What is to say that Cro-Magnon or Neanderthal were immune to diseases we've long forgotten? At least in the modern era they'd have a good chance of being cured of modern ailments.We are not descended from Neanderthals, they are more like cousins than ancestors. I don't believe there is evidence either of these groups lived to be much over 30 so I just don't have the same picture of the noble savage you seem to have. I'm sure they were afflicted by plenty of pathogens in their day.

[skeptigirl]

This is simply not true. Firstly, we've not lost immunity to diseases. Those diseases still exist within the environment, such as Black Plague. One of the main reasons Black Plague really isn't a threat anymore is not because we're immunised to it, but rather that the survivors of the outbreaks in the past have passed on their immunity to current generations.I believe the majority of the world's populations are susceptible to plague. The reason it isn't a big problem anymore is antibiotics kill it.

Measles, mumps, smallpox, chicken pox, influenza, all sorts of fevers, etc., etc. are other examples.There probably is some population immunity to influenza when you see a 2% fatality rate such as with the last great influenza pandemic (1918). But there's still a pretty good chance a new strain could overcome our genetic immunity. The H1N1 strain from 1918 actually became attenuated itself rather that human survivors passing on genetic protection. When a rapidly spreading virus like influenza kills its host, the host cannot spread the infection. So milder and milder strains are naturally selected.

And as you noted, Europeans had a lot of genetic resistance to measles, smallpox and TB. While smallpox is gone for the moment, the other two are still more severe in Pacific Islanders (including Australian Natives) and Native Americans.

[skeptigirl]

....

Plague is actually another good example. The simple fact is that we have not eradicated plague, but simply gotten sufficiently resistant to it that it no longer spreads quickly. There are still something like 100 cases a year in the USA -- but no one catches the plague, even in the pneumonic variant which is spread directly from person to person. The fact is, we've developed resistance to infection by that particular bug, enough to reduce it from a global killer to a nuisance.

The "Spanish flu" that killed more people in 1918 than the First World War is another good example; that particular variant is still around, but it's so harmless that they don't even bother including it in the anti-flu cocktail any more.

Similarly, look up the death rates and infection rates for syphillils and how we've co-evolved with the spirochete since the 1500s.
...You need to check your facts here. We have a handful of plague cases at the most in this country every year, more like 10-15. No way are there 100 a year. And again, it is antibiotics that make the difference. I'm not sure anyone knows how susceptible the population is to pneumonic plague since we don't let human cases spread. But one big clue is that we don't have too many mild cases. Every case of plague in the US can usually be traced back to the rabbit, squirrel, and occasional cat that the human got the flea bites from. If there were mild cases you'd have severe cases with no animal exposure history.

CDC Plague Web page. (http://www.cdc.gov/ncidod/dvbid/plague/index.htm)Today, modern antibiotics are effective against plague, but if an infected person is not treated promptly, the disease is likely to cause illness or death.

And syphilis is still a deadly disease. Cases have been minimized by contact tracing, mass screening programs and antibiotics.

CDC syphilis fact sheet. (http://www.cdc.gov/std/syphilis/STDFact-Syphilis.htm)

[autumn1971]

Just to add to skeptigirl's point, drkitten, the great flu pandemic actually killed a greater number of young adults than any epidemic before or since, so the idea of genetic immunity would require a huge amount of evidence to support it, as opposed to the evidence that the virus itself became less potent. A virus that not only kills quickly, but kills those infected who are of optimal breeding age in abnormally large ratios, is a terrible example of one whose non-virulence now is explained by the genome of its victims.

[Roboramma]

In the modern developed world everyone views procreation as a right. There is, therefore, no natural selection. In addition medical advances have led to us managing to keep in the gene pool those individuals who otherwise would have left it.

Let's look at this from another perspective. Say there's a gene that causes an increased risk of diabetes (or some other disease or condition that we are good at treating with modern medicine), but also has a phenotypic expression of, say, increased height. Under previous conditions, when that disease wasn't treatable, the gene would have been selected against (well, depending upon the balance of it's affects, but assume that it was deadly enough to be selected against). Now however, due to the change in the environment (we can treat the disease, so the gene is no longer so deadly), it's actually selected for, because of it's other affects.

So what happens? In this example, being able to treat diabetes means people evolve to be taller.

The point being that because we've removed problems that natural selection has to "solve" it's free to dedicate our body's resources to other things. I've heard a similar argument that suggested that when our ancestors learned to use fire, and thus could take in more calories, that freed the brain to evolve to become larger. How is that the same?

Under the "economic" conditions before fire, growing a larger brain might have been selected against, because it's owner would require a greater caloric intake, and thus be more likely to starve. When the environment changed, those with slightly larger brains could still get those extra calories they needed - not necessarily because their brains made it easier to get those calories, but simply because getting those calories wasn't as difficult as it was in the old environment. In this situation the advantages of the brain in other ways might (for example, when attracting mates) outbalance the caloric cost.

Similarly, when diabetes wasn't treatable, devoting resources (or making biochemical concessions) to not being diabetic was the best choice. Now, when it is treatable, devoting fewer resources there, and thus having more for other things makes sense.

So, if larger brains are still being selected for, curing diseases might actually lead to an increase in brain size. Or increased resistance to the diseases that we can't cure so well.

Another example might be the fact that we are able to artificially augment fertility. This means that both men and women are having children at older ages than in the past. The cool thing about that is that living to that age should then be selected for (because they can have more children by living longer). So fertility treatments might actually be creating a selective pressure for longevity. Or even for things like risk aversion (take fewer risks as an eighteen year old and you're more likely to live to be forty. If producing children at forty is more likely than before, the cost-benefit analysis of risk taking at 18 changes). More obviously it could result in greater resistance to the diseases of old age.

We seem to have evolved over the past years/centuries/millenia to be taller, better looking and, perhaps most crucially, smarter. Or at least better able to manipulate our environment.
Actually, from what I know, our hunter-gatherer ancestors ten thousand years ago had an average height similar to that of modern Europeans.

As to better looking - while I agree with DrK that there is a selective pressure for attractiveness, and it seems to be as strong now as ever, that doesn't mean that how good looking we are has been increasing with time. The selective pressure might only keep it stable at a certain level. I don't know one way or the other, though.
Regarding smarter - I remember reading recently (maybe last year) about some research that showed a couple of gene changes relating to the development or function of the brain, that happened within the last ten thousand years (maybe less? don't recall). Whether these genes influence intelligence, I don't know, but it's a good guess. Can anyone remember what I"m talking about?

There seem to be no selection pressures at any level of modern western society any more so have we stopped evolving?
I can think of one thing that's likely to be selected for - any gene that tends to reduce willingness to use contraception. It doesn't have to be specific to that obviously, but a gene that reduces risk aversion would probably do it. How about genes that tend to increase the likelihood of wanting children? For example, we have a tendency to be annoyed by the crying babies. If there were a gene that influenced that tendency in a way that resulted in a reduction of the annoyance (it doesn't necessary have to be specific to baby crying) it might lead to a tendency to having more children. A similar affect might occur with genes that caused infants to be less fussy - those carrying the gene would tend to have less fussy infants, and maybe thus be more likely to have more than one child.

Of course those are just speculations. How knows exactly what genes (with what phenotypic expressions) are available, or how the selective pressures would apply to them? I sure don't. But the point is that in this modern environment plenty of selective pressures can be imagined. And plenty that I don't imagine are probably operating.

If we have, what effect will this have on future generations? Are we storing up stupidity and illness for our descendants? Well, if we continue in an environment like this one for many generations, then there was a sudden change that returned our descendants to the ancestral environment of 10,000 years ago, say, they'd probably be less well adapted to that old environment than were our ancestors.
Similarly if you threw me in to the Precambrian sea I'd probably do less well than did one of my Precambrian ancestors in that environment.

[Dymanic]

One of the main reasons Black Plague really isn't a threat anymore is not because we're immunised to it, but rather that the survivors of the outbreaks in the past have passed on their immunity to current generations.

Since immunity is an aquired characteristic, this is an argument for Lamarkism. It's important to distinguish between aquired immunity and genetic predisposition. I also don't think it would be easy to make a case for there presently being less genetic predisposition to plague than in times past. Skeptigirl's explanation (antibiotics) seems simpler.

The H1N1 strain from 1918 actually became attenuated itself rather that human survivors passing on genetic protection. When a rapidly spreading virus like influenza kills its host, the host cannot spread the infection. So milder and milder strains are naturally selected.Since a "strain" consists of huge numbers of individual virions, this looks like an argument for group selection (not to say that it should be dismissed on that basis, but I think it needs extra support). It is intuitively obvious that the strain which preserves its host is more likely to be transmitted, but this seems to run counter to the pressures which would favor one individual virion over another in the same host. A declaration like: "the virus has attenuated itself" might be made with more confidence if more were known about exactly what it is that makes one strain more virulent than another, but for the time being I think we should be at least as cautious about that as we are in observing that humans are "taller, smarter, and better looking" than they used to be, despite the ease with which we might imagine how selection might favor those that are.

[The Great Hairy One]

I believe the majority of the world's populations are susceptible to plague. The reason it isn't a big problem anymore is antibiotics kill it.


Quite possible. I'd wonder why there were no major plague outbreaks in the 1800's/early 1900's though.

Since immunity is an aquired characteristic, this is an argument for Lamarkism. It's important to distinguish between aquired immunity and genetic predisposition. I also don't think it would be easy to make a case for there presently being less genetic predisposition to plague than in times past. Skeptigirl's explanation (antibiotics) seems simpler.


It's most definitely not an argument for Lamarkism. On the contrary, some members of a large population would have, due to variation in allele frequency, a natural resistance to the effects of the disease. This would confer a definite advantage in either resisting or surviving the disease itself, leading to an increase in the frequency of these alleles within the overall population. Offspring of these organisms would pass to their offspring a higher chance of being resistant, due to a lower number of possible alleles at certain loci.

This is standard population genetics.

Cheers,
TGHO

[skeptigirl]

....Since a "strain" consists of huge numbers of individual virions, this looks like an argument for group selection (not to say that it should be dismissed on that basis, but I think it needs extra support). It is intuitively obvious that the strain which preserves its host is more likely to be transmitted, but this seems to run counter to the pressures which would favor one individual virion over another in the same host. A declaration like: "the virus has attenuated itself" might be made with more confidence if more were known about exactly what it is that makes one strain more virulent than another, but for the time being I think we should be at least as cautious about that as we are in observing that humans are "taller, smarter, and better looking" than they used to be, despite the ease with which we might imagine how selection might favor those that are.I do not believe this is the hypothesis of skeptigirl, Dym. I'm pretty sure it is what the evidence shows.

While there may be individual virons within an infected organism which have some significant mutation, the vast majority of individual virons have mutations which have no significant effect. So strains of influenza can be thought of more like a wave than a bunch of individuals all competing for selection.

I cannot share with you in this post all I have been reading in the last 4 years about the genetic drift of the HPAI H5N1 virus, you'll have to do your own reading. But I can tell you there are currently 4 or so major "clades" and a lot of genetic exchanges between the clades.

Regardless, it is not just intuitive but easily demonstrated that severe diseases with rapidly evolving viruses like influenza will always drift toward attenuation. Highly pathogenic strains while we don't have centuries of molecular evidence appear rather suddenly then become attenuated. I am not aware of influenza strains which drifted toward greater and greater pathogenicity over time. Are you?

[Dabljuh]

To answer the OP's question:

Yes, genetical evolution has come to a halt with humans. We keep the weak alive, we give even the stupid and the retarded opportunity to procreate. That's the unstated goal of medicine: To completely halt nature in its natural course.

But memetical evolution is faster than ever. We are getting taller, smarter, better, more beautiful by the minute, not because of genetical changes, but because of ongoing improvements to cultural concepts, knowledge that is being spread in society. Ideas are born, mutate, battle for life, and are selected by the most cruel process imaginable: Criticism. The battlegrounds for these new evolutionary entities are our heads, air filled with voices, and forums such as this one.

Evolution is a tautological law of nature. But genetical evolution, which is just a subset of memetical evolution, has come to a halt in terms of speed, when compared to how fast knowledge increases in society.

[skeptigirl]

Quite possible. I'd wonder why there were no major plague outbreaks in the 1800's/early 1900's though....Because people learned to isolate infected persons. And I believe the Black Death of Europe in the 1400s involved a large rat and flea infestation as an important factor in the extent of the epidemic.

Epidemiologic Determinants for Modeling Pneumonic Plague Outbreaks (http://www.cdc.gov/ncidod/eid/vol10no4/03-0509.htm) Documented 20th century outbreaks of primary pneumonic plague were often rapidly contained once they came to the attention of public health authorities (Figure 3). Even in the pre-antimicrobial era when outbreaks were not specifically identified as plague (e.g., the outbreak in Oakland in 1919 [24] that was thought to be a deadly form of influenza), the isolation of ill persons and observation and isolation of contacts were sufficient to rapidly control the outbreak. Contact tracing and isolation tended to be immediately effective because patients were infectious for only a short time, were very ill and unlikely to go out into the community, and any subsequent infections tended to be in those already caring for the patient (Figure 4). Very rarely were there cases where a prior infectious contact could not be identified. In addition, modern antimicrobial prophylaxis, when given in the incubation period, is close to 100% effective for pneumonic plague, greatly reducing any prospects of transmission from infected, but not yet symptomatic, persons (3, 22, 26, 34, 35). The subsequent modeling therefore assumes that once an outbreak has been identified, further transmission will be stopped. It is further assumed that a cumulative number of deaths are likely to have occurred before an outbreak comes to the attention of public health authorities and appropriate interventions are put in place, denoted D0.

Risk of Person-to-Person Transmission of Pneumonic Plague (http://www.journals.uchicago.edu/cgi-bin/resolve?id=doi:10.1086/428617&erFrom=-3265452999134312473Guest)Historical accounts and contemporary experience show that pneumonic plague is not as contagious as it is commonly believed to be. Persons with plague usually only transmit the infection when the disease is in the endstage, when infected persons cough copious amounts of bloody sputum, and only by means of close contact. Before antibiotics were available for postexposure prophylaxis for contacts, simple protective measures, such as wearing masks and avoiding close contact, were sufficient to interrupt transmission during pneumonic plague outbreaks. In this article, I review the historical literature and anecdotal evidence regarding the risk of transmission, and I discuss possible protective measures.

[skeptigirl]

To answer the OP's question:

Yes, genetical evolution has come to a halt with humans. We keep the weak alive, we give even the stupid and the retarded opportunity to procreate. That's the unstated goal of medicine: To completely halt nature in its natural course.

But memetical evolution is faster than ever. We are getting taller, smarter, better, more beautiful by the minute, not because of genetical changes, but because of ongoing improvements to cultural concepts, knowledge that is being spread in society. Ideas are born, mutate, battle for life, and are selected by the most cruel process imaginable: Criticism. The battlegrounds for these new evolutionary entities are our heads, air filled with voices, and forums such as this one.

Evolution is a tautological law of nature. But genetical evolution, which is just a subset of memetical evolution, has come to a halt in terms of speed, when compared to how fast knowledge increases in society.Why should we accept your wisdom here 'W'? You clearly have a poor understanding of HIV and virology (http://forums.randi.org/showthread.php?t=87321). This post indicates you have a poor understanding of the mechanisms of evolution as well.

If you are going to post these declarations of fact it would be a lot more credible if you could support your claims with something other than innate wisdom. I find it is great for learning new things as well to look for supporting citations.

[ReligionStudent]

To answer the OP's question:

Yes, genetical evolution has come to a halt with humans. We keep the weak alive, we give even the stupid and the retarded opportunity to procreate. That's the unstated goal of medicine: To completely halt nature in its natural course.

But memetical evolution is faster than ever. We are getting taller, smarter, better, more beautiful by the minute, not because of genetical changes, but because of ongoing improvements to cultural concepts, knowledge that is being spread in society. Ideas are born, mutate, battle for life, and are selected by the most cruel process imaginable: Criticism. The battlegrounds for these new evolutionary entities are our heads, air filled with voices, and forums such as this one.

Evolution is a tautological law of nature. But genetical evolution, which is just a subset of memetical evolution, has come to a halt in terms of speed, when compared to how fast knowledge increases in society.

There is still genetic evolution. People still continually die of disease, etc (especially when you get beyond a western bias) and there is still continual sexual selection based on such things as indicators of health and the ability to provide for young.

what the heck do you mean genetical (not a word) evolution is a subset of memetical (not a word) evolution? This makes no sense. It may be (if you take an extremely hard core view based on behavioral ecology) to claim the opposite, but there is no ground to claim genetic evolution as being a subset of memetic evolution.

[Taffer]

To answer the OP's question:

Yes, genetical evolution has come to a halt with humans. We keep the weak alive, we give even the stupid and the retarded opportunity to procreate. That's the unstated goal of medicine: To completely halt nature in its natural course.

But memetical evolution is faster than ever. We are getting taller, smarter, better, more beautiful by the minute, not because of genetical changes, but because of ongoing improvements to cultural concepts, knowledge that is being spread in society. Ideas are born, mutate, battle for life, and are selected by the most cruel process imaginable: Criticism. The battlegrounds for these new evolutionary entities are our heads, air filled with voices, and forums such as this one.

Evolution is a tautological law of nature. But genetical evolution, which is just a subset of memetical evolution, has come to a halt in terms of speed, when compared to how fast knowledge increases in society.

No.

As an evolutionary geneticist, I can emphatically tell you that you are wrong.

[Dymanic]

It's most definitely not an argument for Lamarkism. On the contrary, some members of a large population would have, due to variation in allele frequency, a natural resistance to the effects of the disease. This would confer a definite advantage in either resisting or surviving the disease itself, leading to an increase in the frequency of these alleles within the overall population.
The degree to which susceptibility is a result of genetic factors versus individual immunological history (as well as nutritional or other factors) is not at all clear, but (obviously) only genetic predisposition is passed to offspring. I'd recommend that you avoid referring to natural resistance of this type as "immunity", lest it be confused with "aquired immunity", which (as the term suggests) is not passed on.

I do not believe this is the hypothesis of skeptigirl, Dym.I realize that you did not originate the idea, but surely your extensive reading on the subject has revealed that the conventional wisdom in this matter has recently been brought into question.

it is not just intuitive but easily demonstrated that severe diseases with rapidly evolving viruses like influenza will always drift toward attenuation.This seems like a good place for an exchange of cites. Mine is from a November 2006 WHO report (http://www.who.int/csr/resources/publications/influenza/WHO_CDS_EPR_GIP_2006_3.pdf)

"One especially important question that was discussed is whether the H5N1 virus is likely to retain its present high lethality should it acquire an ability to spread easily from person to person, and thus start a pandemic. Should the virus improve its transmissibility by acquiring, through a reassortment event, internal human genes, then the lethality of the virus would most likely be reduced. However, should the virus improve its transmissibility through adaptation as a wholly avian virus, then the present high lethality could be maintained during a pandemic."

I am not aware of influenza strains which drifted toward greater and greater pathogenicity over time. Are you?I think you mean virulence. And no, I'm not -- but there are examples of viruses (smallpox and malaria, to name two) which have not drifted toward attenuation, either. Saying that empirically all observed examples of influenza have drifted toward attenuation is not the same as saying that theoretically every influenza virus MUST do so.

It's nice to have a platform from which to launch predictions, and mutation/selection provide that, but (as Gould was fond of pointing out) it's easy to become so infatuated with the power of these theoretical tools as to lose sight of an important fact: we don't know everything yet, and these entities are under no obligation to conform to our expectations.

[articulett]

Evolution doesn't stop, silly. We just live in a small period of time so it looks static from our time frame. The people who reproduce the most will be the ones who will have descendants populating the gene pool in the future. And given the propensity of the stupid for spawning, I am rather glad that I won't be around. But good and useful and true information tends to spread fast via the internet too... so as soon as we can erase this "faith is a good way to know something" meme, then the masses can have access to the steady supply of facts coming out of science all the time.

[articulett]

Thanks ancestors! Because of you I can enjoy both cheese and beer! :D

And sex!

[The Great Hairy One]

To answer the OP's question:

Yes, genetical evolution has come to a halt with humans. We keep the weak alive, we give even the stupid and the retarded opportunity to procreate. That's the unstated goal of medicine: To completely halt nature in its natural course.

But memetical evolution is faster than ever. We are getting taller, smarter, better, more beautiful by the minute, not because of genetical changes, but because of ongoing improvements to cultural concepts, knowledge that is being spread in society. Ideas are born, mutate, battle for life, and are selected by the most cruel process imaginable: Criticism. The battlegrounds for these new evolutionary entities are our heads, air filled with voices, and forums such as this one.

Evolution is a tautological law of nature. But genetical evolution, which is just a subset of memetical evolution, has come to a halt in terms of speed, when compared to how fast knowledge increases in society.


This is pretty much completely wrong. It's so wrong, I barely know where to start with the criticism.

Firstly, keeping the "weak" alive does not change the fact that human evolution is still taking place. Allowing "these people" (you're not a supporter of eugenics are you?) doesn't change the fact that human evolution still occurs.

Secondly, changes in phenotype are not so much to do with memes, rather they are to do with improvements in environment and lifestyle.

Finally, evolution is not a tautology, in neither senses of the word.

Cheers,
TGHO

[The Great Hairy One]

Because people learned to isolate infected persons. And I believe the Black Death of Europe in the 1400s involved a large rat and flea infestation as an important factor in the extent of the epidemic.

Epidemiologic Determinants for Modeling Pneumonic Plague Outbreaks (http://www.cdc.gov/ncidod/eid/vol10no4/03-0509.htm)

Risk of Person-to-Person Transmission of Pneumonic Plague (http://www.journals.uchicago.edu/cgi-bin/resolve?id=doi:10.1086/428617&erFrom=-3265452999134312473Guest)


All fascinating information, thanks for that. I also had a read through:
http://en.wikipedia.org/wiki/Black_death
and it seems as though there's still a bit of controversy over the exact causes of the outbreaks in the 1400's and then on.

I do think that there is some form of genetic resistance to the disease within human populations, whether or not it has enough of a protective effect to stop an outbreak, I do not know. It's definitely an area worth further reading! :)

Cheers,
TGHO