Human Evolution

[HappyCoder]

In this modern age we are able to cure many dieseazes and can keep people alive when the would have otherwise died. We are moving towards the point where everybody lives no matter what genetic or non-genetic contintions they may have. I do think this is a good thing I value all human life. I am wondering what this does for natural selection and for evolution.

[insane_alien]

yeah, everybody lives longer, but not everyone reproduces. there are other forms of selection than simply survival of the fittest, there is sexual selection as well.

 

it is a common misconception that the only thing about evolution is natural selection.

[ydoaPs]

I value all human life

 

What's so special about human life?

[Phi for All]

I've often wondered if our unique civilization-building capabilities might offset the evolutionary damage we may do by thwarting natural selection.

[CDarwin]

In this modern age we are able to cure many dieseazes and can keep people alive when the would have otherwise died. We are moving towards the point where everybody lives no matter what genetic or non-genetic contintions they may have. I do think this is a good thing I value all human life. I am wondering what this does for natural selection and for evolution.

 

You're falling prey to the common misconception suggested by Herbert Spencer's phrase "survival of the fittest." In actuality, survival isn't the primary subject of selection. It is reproductive success. In the common example, a woman who lives to thirty and gets hit by a bus but has two children is more evolutionarily successful than the woman who lives to be a hundred years old but has no children.

 

All that is necessary for evolution to happen is differential reproductive success. As soon as you have that, you have natural selection, and in the rapidly changing cultural world of Homo sapiens differential reproductive success is rampant and the parameters that determine more or less successful individuals are almost constantly changing. That is why more genetic changes have accumulated in the past 50 thousand years than in the previous several million of human evolution since the divergence from chimpanzees. So, contrary to common assumption, evolution is actually speeding up.

 

http://news.nationalgeographic.com/news/2007/12/071211-human-evolution_2.html

[SkepticLance]

The problem with evolution in the modern context is that it is likely to drive in directions we consider disadvantageous. Genes for harmful traits that would have been removed from the gene pool just a couple hundred years ago will now survive. Many will increase in frequency.

 

I do not think this will be a long term problem, though. As our knowledge and skill with genetics improve, we will be able to gene manipulate zygotes or early embryos to make sure that all are healthy. In fact, within another couple hundred years, all new born children should be genetically superior to any born today - with genes for high intelligence and athletic ability, and good health.

[insane_alien]

as long as that doesn't lead to a gattaca type scenario...

[CDarwin]

The problem with evolution in the modern context is that it is likely to drive in directions we consider disadvantageous. Genes for harmful traits that would have been removed from the gene pool just a couple hundred years ago will now survive. Many will increase in frequency.

 

But the reason these 'bad' genes are propagating is obviously because they are no longer 'bad' in some societies. That means that more or less they are the ones that we can handle. If we couldn't they wouldn't be there. The nastiest stuff (and stuff we might not necessarily think so nasty) that really hampers reproductive success will continue to be pruned. So what if we'll all need glasses?

 

And remember that you never "lose your shot" with evolution. It's not "get rid of bad eye-sight now or it will become so prevalent you can never get rid of it." If needing eye-correction become seriously maladaptive in the future it will decrease in frequency quickly enough.

 

As for genetic engineering. Who knows.

[bombus]

yeah, everybody lives longer, but not everyone reproduces. there are other forms of selection than simply survival of the fittest, there is sexual selection as well.

 

it is a common misconception that the only thing about evolution is natural selection.

 

Sexual selection is a form of natural selection.

[insane_alien]

i had mutations in mind when i wrote that last bit.

[TreyFlip]

I think about this alot. I dont see the human population going through more evolution but mixing up different traits from all over the place no matter what they're for. It does'nt seem like much of a problem untill you think about the impact on a familys resource$ when a loved one needs some kind of major medical work done such as surgery to remove a brain tumor or the resources put forth by an entire community to help find better treatments for brain tumors. I'm not saying we should throw the genetically inferior off a cliff but being in that kind of delima will deffinately alter a family's future.

 

This philosophy probably does'nt cover most scenarios but it's true to some extent. Im pretty confident in my genetic makeup so far seeing as how im only 17. My dream is to live in a geographically stable area where the effects of the inevitable global issues arising wont kill my offspring.

[HappyCoder]

So what if we'll all need glasses?

 

I do agree with what you said about bad genes not really being bad anymore but what if there was some sort of genetic blindness that developed. Something a little worse then everybody needing glasses.

[CDarwin]

I do agree with what you said about bad genes not really being bad anymore but what if there was some sort of genetic blindness that developed. Something a little worse then everybody needing glasses.

 

Then it would probably be selected against. I'm not sure on any data covering fecundity in blind people, but I would hazard to guess it would be rather lower than the average.

[ecoli]

In this modern age we are able to cure many dieseazes and can keep people alive when the would have otherwise died. We are moving towards the point where everybody lives no matter what genetic or non-genetic contintions they may have. I do think this is a good thing I value all human life. I am wondering what this does for natural selection and for evolution.

It just changes the selection pressures on human populations... However, evolution is just as active as in history.

 

I believe the main mode of selection these days would be sexual selection.

[SkepticLance]

Prof. John Hawks of the university of Wisconsin has been involved in studying recent human evolution using current human genetic variability to show what changes have happened recently. Some of his thoughts are on :

 

http://johnhawks.net/weblog/reviews/genetics/brain/lahn_2005_aspm_microcephalin_science.html

 

The quote below shows several recent genetic changes, for two genes considered to be involved in brain development, showing evolution in the very recent past.

 

"Haplogroup D for Microcephalin apparently came under selection around 37,000 years ago (confidence limit from 14,000 to 60,000 years ago). This is very, very recent compared to the overall coalescence age of all the haplotypes at the locus (1.7 million years). Some populations have this allele at 100 percent, while many others are above 70 or 80 percent. Selection on the allele must therefore have been pretty strong to cause this rapid increase in frequency. If the effect of the allele is additive or dominant, this selective advantage would be on the order of 2 or 3 percent -- an advantage in reproduction.

 

The story for ASPM is similar, but even more extreme. Here, the selected allele came under selection only 5800 years ago (!) (confidence between 500 and 14,100 years). Its proliferation has almost entirely occurred within the bounds of recorded history. And to come to its present high proportion in some populations of near 50 percent in such a short time, its selective advantage must have been very strong indeed -- on the order of 5 to 8 percent. In other words, for every twenty children of people without the selected D haplogroup, people with a copy of the allele averaged twenty-one, or slightly more. "

[lucaspa]

I've often wondered if our unique civilization-building capabilities might offset the evolutionary damage we may do by thwarting natural selection.

 

Remember, natural selection works to adapt a population to an particular environment. There are no absolutely "good" traits or absolutely "bad" ones. We are adapting to our current environment, which includes all that technology. You are worrying about being able to survive in an environment without all the technology.

 

Let's look at this. Before technology, Stephen Hawking would have died childless. Thanks to the technology, he has children. Do we really want to lose all of Hawking's alleles in the pursuit of some ideal that some alleles and traits are universally bad?

 

We are not free of natural selection. Just let it work.

[immortal]

IMO there is no such thing has a bad gene or a good gene they just become bad in a particular environment and when the environment changes the same gene which you called it has bad may not be bad at all.

 

Now a days I am hearing that some people wants to have a conscious selection so that they can eliminate bad genes and I am afraid that this conscious selection will never be able to design things as efficiently as natural selection and it may lead to extinction.

 

Cultural evolution does'nt block biological evolution it just takes it in a different path and we are still evolving. Many say that things are changing due to global warming and we need to use renewable resources to stop it. I think it has already reached a point where it can not be stopped unless we find some high tech solution. The problem with humans is that they don't want to change they want the environment to adapt according to them. I think this is the time to change not only mentally but also biologically and the best way to get prepared for the changing environment is to have reproductive success so go on and produce as many offsprings as you can and one thing don't take too much burden and I think we need to take chances very seriously in a world were everything works by chance.

[SkepticLance]

Immortal said

 

"there is no such thing has a bad gene or a good gene"

 

I suspect that people suffering from haemophilia or Huntingtons Disease might disagree with you. Some genes are just plain bad, with no redeeming features. No change in environment will miraculously make them good.

[immortal]

Immortal said

 

"there is no such thing has a bad gene or a good gene"

 

I suspect that people suffering from haemophilia or Huntingtons Disease might disagree with you. Some genes are just plain bad, with no redeeming features. No change in environment will miraculously make them good.

 

Well I said that based on the sickle cell gene which provides protection in a malarial region. If I could remember exactly there was a report on NGC where there was a selection of a population of sheeps which were struggling to walk

properly and this kind of selection was because of the owner who provided food for them and those sheeps which were normal and more in number went first to eat but they did'nt had sufficient meal due to large numbers and there by less food. But those abnormal sheeps which went last and fewer in number had enough meal. The force of natural selection acts using different agents here the agent was human beings.

[MedGen]

Immortal said

 

"there is no such thing has a bad gene or a good gene"

 

I suspect that people suffering from haemophilia or Huntingtons Disease might disagree with you. Some genes are just plain bad, with no redeeming features. No change in environment will miraculously make them good.

 

Ah, but the common misconception here is that it is the gene that is good or bad. Technically it is the allele for that loci that may result in a deleterious effect, particularly with respect to homozygosity. As previously mentioned this is very much the case with the sickle cell allele. Heterozygosity (sickle cell trait) effectively confers a selective, and thus reproductive, advantage because it confers considerable protection against malarial infection. However, homozygosity is severely detrimental to the carriers health because it results in sickle cell anaemia. This is the cost of natural selection by balancing the advantages and disadvantages of an allele. As a result of its effect it is highly unlikely that it will ever reach a 100% frequency within a population as natural selection will continuously weed out the homozygous carriers.

 

Unfortunately it is not always as simple as this as. There are many alleles that may confer a selective advantage where heterozygosity occurs at a loci, in 2005 this was highlighted by a study into the possible effects on intelligence of the Tay-Sachs causing allele within Ashkenazi Jewish populations. Once again because it is a recessive condition heterozygosity provides a sexually selective advantage where increased intelligence is desirable.

Natural History of Ashkenazi Intelligence

Although this paper is highly controversial and no further evidence has been forthcoming, it merely highlights the possibility of such correlation and selective advantage occuring.

 

As for the case of Huntingdon's this is the result of an insertion of a VNTR (variable number tandem repeat), I forget exactly what the sequence is, but because it does not present until after reproductive age it is passed on to its offspring, therefore it can be considered as being selectively neutral. Now if a diagnostic tool is created that can screen for, and eventually correct, these VNTR's then the allele frequency will fall quickly with a few generations.

 

I think many people often overlook the importance of neutrality and genetic drift and tend to concentrate solely on what is selectively advantageous. Note I am not disputing selection pressure, merely that it is most definitely not the whole picture.

[YT2095]

since we have Nothing to compare with, how do we know that when a species becomes advanced enough to affect these changes being discussed in the OP, that That also isn`t part of Natural Selection?

 

we are after all just Animals, and obeying our drives, there`s nothing UN-Natural about it.

[ParanoiA]

What's so special about human life?

 

Absolutely nothing. So why so concerned about global warming then?

 

What's so special about any life?

[MedGen]

What's so special about any life?

 

It exists in this universe, that pretty special, and for all we know it could be the only life in this universe, although I doubt that supposition to be true.

[ParanoiA]

I actually agree with you. I'm asking YDOAPS specifically.

[stingray78]

Uhh, good question!! Lets put it this way. In general, Pretty people f*ck with pretty people. Rich people f*uck with rich people. Smart people f*ck with smart people. Ugly people f*ck with ugly people. Stupid people f*ck with stupid people. I know it sounds quite hard, but It's true(in general). So in terms of evolution, I think the human race will divide into too: one "stupid ugly" race and one pretty smart race". You just need to look around on all the steretypes. Well, that's my point of view, but it's a fact evolution continues.