Are WE still evolving?

[ZerroEnna]

Since, I only know about one theory of evolution. Which happens to be natural selection, I admit that I am somewhat ignorant on the subject. However, I understand that natural selection can no longer be applied to humans as we are now. So my question is; are will still evolving? What other theories are out there that I can read about. Anything that would help me find an answer? Any feedback is appreciated.

 

[Skaloop]

However, I understand that natural selection can no longer be applied to humans as we are now.

Sure it can. Why do you think otherwise?

There are still natural selection pressures that can act on humans, they're just different than they used to be. Predators aren't much of a worry anymore, but say the AIDS epidemic continues to spread. Someone who has some sort of immune system oddity that prevents him from contracting HIV (or at least prevents it from killing him) will have better survival chances than someone who succumbs more readily to AIDS. This is all hypothetical, of course, but it should give the idea.

Natural selection is still occuring on all species, so evolution is continuing for all species. Some are evolving quickly, and some (like humans) are evolving slowly. There are various reasons for this. Some animals have already become so specialized to their specific niche that further variation doesn't really offer any advantage, so they don't lead to changes through natural selection. For humans, our population is so large and there is so much inter-bredding between distant populations that it will take a lot longer than "usual" for beneficial traits to accumulate to such a degree that they can make a significant difference. Also, medical advances mean that many traits that would have previously been selected against can be countered.

And also remember that it takes millions of years for changes to accumulate, so from our localized viewpoint, things look unchanging when they really aren't.

 

[ZerroEnna]

It doesn't because we have the ability to change our enviroment. Yes, while now we now fall victim to AIDS we wil eventually come up with a cure. As with all diseases etc. etc. Our "manufactured" adaptability works much faster than natural selection does. Therefore our ability to save ourselves makes it moot.
Edit: I missed the part about slowly working my first time through, sorry. I at first thought of that too. That its working SLOWLY not altogether stopping. Then I started to think about that natural selection causes evolutions that are advantageous. What would be advantageous to a human? Being smarter? Well there are plenty of smart people who go off and marry someone who is not their equal in terms of intelligence and have kids. Do we even know that intelligence is in herited? On second thought I don't really want to think about some of these questions. I suppose that lungs that are better able to live in increasingly polluted air would be advantageous, but before any evolution would occur our technology would solve the problem. I am of the opinion that we act and think too fast for natural selection to have an effect on us.

 

[michabo]

We're still evolving, however we have a very large genetic pool which dramatically slows down the pace, and we use technology and social programs to improve our lives, reducing selection pressures. Evolution is most rapid when a population is separated and subjected to strong selection pressures.

 

[Split Rock]

Since, I only know about one theory of evolution. Which happens to be natural selection, I admit that I am somewhat ignorant on the subject. However, I understand that natural selection can no longer be applied to humans as we are now. So my question is; are will still evolving? What other theories are out there that I can read about. Anything that would help me find an answer? Any feedback is appreciated.

There are three basic mechanisms of evolutionary change:
1. Natural Selection
2. Genetic Drift
3. Gene Flow

While natural selection may be limited in its effect on humans because of our technology, we are not invincible. Resistance to fatal diseases, especially ones that are untreatable and effect humans of child-bearing years or younger (such as Testicular cancer) will be selected for.

Genetic drift is random and has a limited effect on large populations, especially large populations that interbred with others.

Gene flow refers to interbreeding between populations, and with humans may allow beneficial genes currently restricted to small isolated populations to expand to a larger population.

So, to answer your question, yes we will continue to evolve, but the effects of evolution on us may well be minor because of our technology. Some negative traits, such as myopia (near-sightedness) may increase in the population, due to a lack of effect on fitness in our technologically advanced world.

 

[Skaloop]

It doesn't because we have the ability to change our enviroment. Yes, while now we now fall victim to AIDS we wil eventually come up with a cure. As with all diseases etc. etc. Our "manufactured" adaptability works much faster than natural selection does. Therefore our ability to save ourselves makes it moot.

There are still selection pressures. AIDS has been around 20 years; no cure yet. Cancer has been around for millenia; no cure yet. Those right there are selective pressures causing natural selection; it's just on a very small scale. The fact that we are able to change our environment may indeed mean that natural selection has a much reduced impact, such that it has been rendered nearly impotent, but it is still acting upon us, even if it is too a lesser degree.

Also, the ability to cure disease, etc., only counters one kind of selection pressure; that of immunity to disease. There are plenty of other ways in which natural selection could act upon humans. It could have to do with intelligence, size, whatever. One hypothesis I jokingly bandy about is that we are evolving into an uglier form, because very attractive women are less likely to have children (for fear of losing their attractiveness), so attractiveness is being selected against. I'm not saying that's true in any way, as it's just an example, but it's just one of myriad ways in which natural selection can act upon humans. That we can't see it happening is due to our constrained timeframe.

 

[Loudmouth]

I often cite this article when this question is asked. The hemoglobin S allele is the famous sickle cell allele. It confers resistance to malaria when the carrier has just one copy, but if you carry two copies of the hemoglobin S allele then you develop sickle cell disease. A new variant, hemoglobin C, does not confer resistance to malaria but it does give the carrier a much better chance of surviving the infection. At the same time, if you carry two copies of the hemoglobin C allele you will have little to know side effects. For this reason, scientists expect the C allele to replace the S allele over time, a perfect example of evolution.

J Evol Biol. 2004 Jan;17(1):221-4.Related Articles, Links

[SIZE=+1]Estimation of relative fitnesses from relative risk data and the predicted future of haemoglobin alleles S and C.[/SIZE]

Hedrick P.

School of Life Sciences, Arizona State University, Tempe, AR 85287, USA. philip.hedrick@asu.edu

Epidemiological studies of genetic differences in disease susceptibility often estimate the relative risks (RR) of different genotypes. Here I provide an approach to calculate the relative fitnesses of different genotypes based on RR data so that population genetic approaches may be utilized with these data. Using recent RR data on human haemoglobin beta genotypes from Burkina Faso, this approach is used to predict changes in the frequency of the haemoglobin sickle-cell S and C alleles. Overall, it generally appears that allele C will quickly replace the S allele in malarial environments. Explicit population genetic predictions suggest that this replacement may occur within the next 50 generations in Burkina Faso.

 

[ZerroEnna]

Well I certainly can't deny it, thats for sure. Its just frustrating, knowing that we are changing and that the only way we will ever be able to see it is in hindsight.

 

[Loudmouth]

Well I certainly can't deny it, thats for sure. Its just frustrating, knowing that we are changing and that the only way we will ever be able to see it is in hindsight.

Just as the old saw says, "The only constant is change."

As others have mentioned, we may actually be able to direct our own evolution. We have already evolved domesticated animals and plants over the last 10,000 years or so. The evolution of maize, for example, is quite amazing.

What does the future hold? Direct genome manipulation. Do you want your child to be a sprinter or long distance runner? Blue eyes or brown? Free of any genetic disease? These may be possible in the near future (100 years or so).

 

[fromdownunder]

The loss of wisdom teeth is one example of natural selection that has been halted by technology - the art of dentistry.

So, people who used to develop impacted wisdom teeth which could quite literally kill them before passing on this gene, now go to a dentist, get them removed and stay in the gene pool.

So, wisdom teeth will last much longer than they otherwise would have.

(I never grew any, and two of my children share this trait).

Norm

 

[I_Love_Cheese]

Yes we re still evolving, in fact I think this is what Gould and Eldrege are describing with punctuated equilibrium. We are going through a stasis period where there is no change in selective pressure or in our case a lessening of overall selective pressure. Our DNA is still mutating and changes are building up but right now they are in small populations and scattered so we don't see them. When the next big change strikes, (end times wars, meteor, virus, whatever) then we will find out just what sort of evolution was built up and we will see a bunch of rapid changes for the new selection pressures.

 

[rmwilliamsll]

this question comes up often enough that i went looking for specific and interesting brain evolution papers.
see:

http://www.nytimes.com/2006/03/07/science/07evolve.html?ex=1144040400&en=d387a9ed4d88ca29&ei=5070
Providing the strongest evidence yet that humans are still evolving, researchers have detected some 700 regions of the human genome where genes appear to have been reshaped by natural selection, a principal force of evolution, within the last 5,000 to 15,000 years.

The genes that show this evolutionary change include some responsible for the senses of taste and smell, digestion, bone structure, skin color and brain function.
Many of these instances of selection may reflect the pressures that came to bear as people abandoned their hunting and gathering way of life for settlement and agriculture, a transition well under way in Europe and East Asia some 5,000 years ago.

...Dr. Pritchard and his colleagues, Benjamin Voight, Sridhar Kudaravalli and Xiaoquan Wen, report their findings in today's issue of PLOS-Biology.

Their data is based on DNA changes in three populations gathered by the HapMap project, which built on the decoding of the human genome in 2003. The data, though collected to help identify variant genes that contribute to disease, also give evidence of evolutionary change.
via vector: http://www.christianforums.com/showpost.php?p=23118966&postcount=7

or:

via vector: http://www.christianforums.com/t2864824-margaret-mead.html#post23124845
which links to: http://home.comcast.net/~neoeugenics/cartw.htm
while googling and reading on the topic of Jewish intelligence and MB i found: http://home.comcast.net/~neoeugenics/IQgenes.htm
as is my custom i backed up to: http://home.comcast.net/~neoeugenics/
posted my response to: http://www.christianforums.com/showpost.php?p=23125290&postcount=9

the one site is rather racist, be careful there.

and the last batch of links:

into an essay on brain evolution:
http://www.jerrypournelle.com/reports/cochran/overclocking.html
http://www.economist.com/science/displaystory.cfm?story_id=4032638
http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pbio.0040087

via vector:
http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pbio.0040072
http://www.christianforums.com/t2795414-a-map-of-recent-positive-selection-in-the-human-genome.html

if you google "selective sweep" you can find any number of genes that are under recent selection pressure.

 

[Praxiteles]

Cancer has been around for millenia; no cure yet. Those right there are selective pressures causing natural selection; it's just on a very small scale. .

Strictly speaking, most cancers are not a selection pressure. This is because the majority of cancers do not develop until well after reproductive maturity. In other words, they don't inhibit reproductive success, which is the crux of selection.

Just wanted to clear that up.

 

[JohnR7]

This is because the majority of cancers do not develop until well after reproductive maturity.

Just what is reproductive maturity? Women can produce babies up to about the age of 50 and men up to about the age of 70. So does that mean more women get cancer then men, or just at a younger age in life compared to men.

 

[h2whoa]

Women can produce babies up to about the age of 50 and men up to about the age of 70.

Some women can produce babies up to about the age of 50.

But the fact of the matter is that most women (and men for that matter) have stopped well before they are 50. Certainly enough not to have a statistical impact.

More to the point though is the issue that if diseases affect people after they have had children then it won't technically be a selective pressure because it doesn't impact on potential reproductive success.

 

[Nooj]

I reckon AIDS and HIV could act as a selective pressure on people. If it does, it will probably be apparent in Africa where health care isn't exactly top-notch and where selective pressure will be the strongest.

Millions of people are infected with the virus. The gene pool will react to it, the only question is how.

No doubt we're evolving, but the changes are probably very, very slight. For most of the human population, selective pressures have dropped away because of the benefits of technology. The human species is truly global. Millions travel from one country to another. Genes from different ethnicities cross over regularly. Even if there is a mutation that confers a slight survival advantage (like a slightly stronger person), that no longer means that the person is more likely to pass on his genes. Most of the world no longer chooses a mate because of his physical strength, speed or stamina. If there's one factor that could potentially lead to selective pressure on a large population, it's phyiscal attractiveness. I'll hazard a guess and say that fair hair, clear skin, slim figures are highly desired traits in females by many American males. These traits may no longer have any survival advantages, but it will be selected anyway by society in general.

But this is too simplified. Technology has pervaded every part of our lives. Blonde hair does not have to be hereditary. Hair can be dyed. Clear skin is achievable by pharmaceutical products. Slim figures are more likely to be attained by dieting and excercise, not genetic traits.

And what people see as attractive traits can also be influenced by change. 150 years ago, people probably found some other trait attractive.

And we musn't forget that beauty is in the eye of the beholder. Some people just don't find blonde people attractive. In other countries, people find dark-skinned people more attractive than blonde people. And these people can immigrate (why don't we use the word 'migrate' for humans anymore?), meaning that evolution is always being pulled in different directions.

Humans have effectively bamboozled evolution. I don't think that humans will evolve significantly without a major selective force.

 

[jwu]

Some women can produce babies up to about the age of 50.

But the fact of the matter is that most women (and men for that matter) have stopped well before they are 50. Certainly enough not to have a statistical impact.

More to the point though is the issue that if diseases affect people after they have had children then it won't technically be a selective pressure because it doesn't impact on potential reproductive success.

Furthermore, as long as the offspring is cared for, if people die not too long after the end of their reproductive period, that's less stomachs for the tribe to feed. In times of scarce food vulnerability to cancer at ages of 40+ may even be selected for.

 

[JDDCH]

I'm a little confused here. Aren't we confusing evolution with genetic variation here? I don't see humans as evolving. We're still humans. What I do see is humans experiencing a normal range of genetic variation as all species do. We flux about a bit as the environments and social patterns change but such variations are alterable as you've all pretty much described. ... it's genetic variation. ... not evolution. ... right?

 

[GoSeminoles!]

However, I understand that natural selection can no longer be applied to humans as we are now. So my question is; are will still evolving?

Yes, humans are still evolving. From National Geographic:

Genome researchers at the University of Chicago have identified more than 700 regions in human DNA where apparently strong selection has occurred, driving the spread of genes linked to a broad range of characteristics.

"These are very recent events—within the past ten thousand years," said Jonathan Pritchard, a geneticist whose laboratory team conducted the study.

The results suggest that humans in different regions have continued to adapt in numerous ways to both environmental changes and cultural innovations. Many of the genetic changes Pritchard's group detected came during or after the emergence of agriculture, beginning about 10,000 years ago, and long after the formation of modern human populations.

Another interesting dimension to human evolution is memetic selection. Memes are basically ideas. Memetic selection appears to be unique to humans in that humans will choose mates based on compatability of ideas, rather than just sexual attraction. For example, a human who holds the Catholic meme may choose to mate only with other humans who also hold the Catholic meme.

 

[GoSeminoles!]

I'm a little confused here. Aren't we confusing evolution with genetic variation here? I don't see humans as evolving. We're still humans. What I do see is humans experiencing a normal range of genetic variation as all species do. We flux about a bit as the environments and social patterns change but such variations are alterable as you've all pretty much described. ... it's genetic variation. ... not evolution. ... right?

Genetic variation = evolution. Genetic variation + lots of time + selection pressure = new species = evolution.