Are we still evolving?

[BusaDave9]

I say no.

What say you?

 

Here's my reasoning: evolution takes place more so in smaller populations. We have heavily populated earth. We can easily travel the whole world over. Native Americans can marry orientals. Africans can marry Europeans. We are blending our genes. That makes the population more bland (for lack of a better word). Now if a small group of humans were to be dropped off on an island without any technologies they would evolve over generations.

 

Also it is no longer 'survival of the fittest'. It is now survival of everyone! If someone is in a horrible accident it is amazing what modern medicine can do. We are also curing diseases.

 

Also the most attractive don't end up having the most kids. People can control their family sizes. We are unlike animals that can't relate sex to offspring. Super models don't end up having a dozen kids. The people with lots of kids have big families because of their beliefs not because they are more attractive.

 

Sure we are evolving a little. You can't stop it completely. I am just saying we are evolving much less than other animals.

 

Am I right or am I right?

[Arete]

No, you're not right. Even a population in perfect Hardy Wienberg Equilibrium and the complete absence of selection will evolve via genetic drift.

 

In the case of humans, a comprehensive study of human evolutionary trajectories was undertaken as a part of the Framingham heart study and showed rapid evolution in a human population. This study showed that women in the Framingham population had evolved to be slightly shorter and stouter, to have lower total cholesterol levels and systolic blood pressure, to have their first child earlier, and to reach menopause later. http://www.citeulike.org/group/13436/article/6436046

Edited December 9, 2014 by Arete

[Robittybob1]

No, you're not right. Even a population in perfect Hardy Wienberg Equilibrium and the complete absence of selection will evolve via genetic drift.

 

In the case of humans, a comprehensive study of human evolutionary trajectories was undertaken as a part of the Framingham heart study and showed rapid evolution in a human population. This study showed that women in the Framingham population had evolved to be slightly shorter and stouter, to have lower total cholesterol levels and systolic blood pressure, to have their first child earlier, and to reach menopause later. http://www.citeulike.org/group/13436/article/6436046

Viruses and cancer causing agents are selecting the fittest all the time, and as the population builds up the viruses mutate faster. I think there is a lot happening behind the scenes. Diets change and we have to evolve to suit the food source. Lactose tolerance, gluten tolerance, casein A1 tolerance are being selected for. OK some individuals are fighting back but it is more difficult to live in a world riddled with lactose, gluten and A1 casein.

As we are busy making new products and chemicals it will be taking the toll on certain genetic types. Resistance to radioactivity (if there is such a thing) could be a good trait to have!

[Ophiolite]

We are arguably evolving faster than ever before. Why?

 

1. A population size that is orders of magnitude larger than what has existed for the greater span of human existence. This provides the opportunity for orders of magnitude more mutations.

2. A radical change in environment for a substantial number of humans. We have become city dwellers. Our ancestors, to give a single example, did not have to survive high levels of nitrous oxides. Evolution is accelerated in novel environments.

3. Precisely because we are using modern medical practices to preserve the lives of individuals who might have died before reproducing we are changing the allele frequencies in the population: that's evolution.

 

Honestly, BusaDave, the notion that we have stopped evolving is just plain silly.

[BusaDave9]

Mutations and genetic drift alone can not cause evolution. You must also have survival of the fittest. You must have the death of those without certain traits. This is basic to evolutionary theory. Otherwise what would orchestrate these changes to head in a certain direction for the entire population?

 

Even a broken leg may mean a fawn may never make it old enough to bear young. Our survival rate is far and above any other animal on earth. It is no longer survival of the fittest. It is survival of everyone. We expect everyone to live several times further than the child bearing years.

Edited December 9, 2014 by BusaDave9

[Arete]

Mutations and genetic drift alone can not cause evolution.

 

This is categorically false. In fact, in small populations, drift can actually overwhelm selection in driving the evolution of a population.

 

E.g.

http://onlinelibrary.wiley.com/doi/10.1111/evo.12464/abstract

http://www.genetics.org/content/194/1/235.short

http://onlinelibrary.wiley.com/doi/10.1111/mec.12524/full

[Greg H.]

 

This is categorically false. In fact, in small populations, drift can actually overwhelm selection in driving the evolution of a population.

 

E.g.

http://onlinelibrary.wiley.com/doi/10.1111/evo.12464/abstract

http://www.genetics.org/content/194/1/235.short

http://onlinelibrary.wiley.com/doi/10.1111/mec.12524/full

This is especially true in populations like humans where there really is no concept of "survival of the fittest". We have, to a very large degree, overcome nature's impact on our evolutionary course in terms of deciding what mutations survive to the next generation.

[BusaDave9]

 

This is categorically false. In fact, in small populations, drift can actually overwhelm selection in driving the evolution of a population.

 

But we are not a small population. We have overpopulated the earth. We are one big population. As I said in my opening post we can quickly and easily travel the whole world. The races are interbreeding and blending. The races are far from being separate species. With more interracial marriages even the races will be less pronounced in the future. If we had one small group of people from one race left on an island for many generations evolution may take place.

With the amount of gene blending going on with our large population what would coordinate the evolution of the entire human species?

 

Edited December 9, 2014 by BusaDave9

[Arete]

 

But we are not a small population. We have overpopulated the earth. We are one big population. As I said in my opening post we can quickly and easily travel the whole world. The races are interbreeding and blending. The races are far from being separate species. With more interracial marriages even the races will be less pronounced in the future. If we had one small group of people from one race left on an island for many generations evolution may take place.

With the amount of gene blending going on with our large population what would coordinate the evolution of the entire human species?

 

 

A large population is still subject to evolution via genetic drift. To claim otherwise is simply false.

[BusaDave9]

 

A large population is still subject to evolution via genetic drift. To claim otherwise is simply false.

"Simply false" "just plain silly" simply wrong. Why? Explain how the entire population of the Earth can evolve in a certain direction.

 

With world travel we are blending our genes, blending the races. Are you with me so far? Do you agree?

Yet, humans the world over are becoming shorter (or maybe taller or maybe whatever). What would cause this in such a large population? Everyone can't suddenly start getting mutations for longer fingers.

[sunshaker]

Evolution gave us an intelligence, and the ability to do what natural evolution could not do alone,

Our next step in evolution will be where we join with technologies , a time will come when there will be a fine line between man/machine/gods,

I believe within the next few hundred years "humans" will be as different to us as we are to Homo habilis.

natural selection will now take a back seat.

[Arete]

"Simply false" "just plain silly" simply wrong. Why?

How about "contrary to all observations"? Evolution can and does occur due to genetic drift, and genetic drift is present large populations.

Explain how the entire population of the Earth can evolve in a certain direction.

 

With world travel we are blending our genes, blending the races. Are you with me so far? Do you agree?

This is a non-sequitur to human populations being under genetic drift. Also, assuming that humanity is a single, panmictic population is also wrong. http://www.sciencemag.org/content/298/5602/2381.full

Therefore, no assumption about unidirectional selection on the human population is either inferred or assumed. Different populations of humans can and do evolve in different ways. Additionally, not all evolution is directional.

Yet, humans the world over are becoming shorter (or maybe taller or maybe whatever). What would cause this in such a large population? Everyone can't suddenly start getting mutations for longer fingers.

Selection pressure - you're actually the one who claimed "Also it is no longer 'survival of the fittest'. It is now survival of everyone!" in the opening post. As I quoted in post #2, the Framingham population is becoming shorter, stouter, to have lower blood pressure, and longer reproductive times. This strongly infers selection for a lower risk of heart disease, and for a longer period of fertility in females. So human populations appear to be actually evolving rapidly in response to selection, rather than the opposite.

[chadn737]

1) No, you don't need selection to evolve. Basic population genetics demonstrates that to be absolutely false.

 

2) The notion that we are still not under selection is also absurd. Advances have allowed us to overcome many historical selective pressures (starvation, certain diseases), although this is not true of the entire world. But to presume that these are the only types of selection at work is to take a very narrow and naive view of selection. Sexual selection can play a very large and important role in human evolution still.

3) Natural selection is about differences in reproductive success, not "survival of the fittest". Rich, successful, atheletic, beautiful people that we would typically think as "the fittest" who never reproduce are losers in the evolutionary game. Their genes have failed to be passed on. High birth rates amongst other populations, such as those who are poor...they are successfully passing on their genes. You now have nations with decreasing birth rates and inverted demographics. These are all factors that will continue to shape human evolution.

The movie is a comedy and inaccurate on many levels, but watch the first 5 mins of Idiocracy. It gets basic Evolution right and more so than any other movie I have ever seen. Selection is all about reproduction. Doesn't matter if the characteristics those reproducing possess what most people think of as those of the "fittest".

[BusaDave9]

So was Darwin completely wrong? His theory explains evolution by natural selection. With natural selection a new species appears roughly every million years (I said roughly so no need to bring up punctuated equilibrium or alligators that have not changed much). I think we agree that survival of the fittest no longer applies to humans but some of you seem to be saying we are evolving faster than ever. How? I get an answer back that it is still possible. I am not saying it's impossible. As I said in my original post:

 

Sure we are evolving a little. You can't stop it completely. I am just saying we are evolving much less than other animals.

 

To say we can now evolve faster without natural selection must mean that Darwin was wrong and natural selection is not the main driving force of evolution. I ask once again, how could this be? What is the main driving force for evolution? Please don't say intelligent design.

Edited December 9, 2014 by BusaDave9

[Ophiolite]

Dave, you seem to completely misunderstand survival of the fittest and selection. Fit is not the equivalent of the fitness you might seek to achieve by regular exercise, fitness is possession of a phenotype - a collection of traits, genetically determined - that work well in your environment.

 

Many sub-Saharan Africans suffer from sickle cell anemia, a genetic condition. This occurs when they inherit the relevant gene from both parents. This is a distinct disadvantage and can prove lethal. But possession of the gene gives one a degree of immunity to malaria, a genuine advantage in sub-Saharan Africa. So populations who have the gene are fitter for that environment than those who do not. The same would not be true if we moved the population to Finland. Keep in mind that evolution works on populations, not individuals.

 

There are heart conditions that will prove fatal before maturity, if not treated. Individuals with these conditions can now survive an reproduce. Why because if they have access to appropriate medical treatment the condition can be dealt with. They are in an environment in which there condition is not terminal. They are fit for that environment. Note that the proportion of persons with the genes for these conditions will tend to increase. That alters the proportion of alleles in the population. That is evolution.

 

So at least four things are giving us more evolution today:

 

1. The introduction of new environments that preserve genes that would have previously proved fatal.

2. The much larger population which can generate more mutations on an absolute scale.

3. The greater mixing of populations across the globe than previously occurred.

4. Far greater variations in environmental conditions (diet, pollution, etc.) than has been the case in the past.

[BusaDave9]

Of course I know what survival of the fittest is. We're talking genetics here. New genetic traits getting passed on to the next generation to the degree to create a new species. I'm still waiting for anyone to point our any reasons we may be evolving faster than other animals. Sickle cell anemia and malaria are child's play in the non-forgiving wilderness. Do you think wild animals don't have disease? We humans can treat diseases. We are even making great progress with genetic diseases and disorders. As Sunshaker alluded to we may even cure genetic diseases with genetic manipulation, but that would be artificial evolution. How's the animal world coming along finding cures to their diseases? Some plants produce chemicals to fight off parasites. Here in Colorado the bark beetle is killing thousands of square miles of lodgepole pine. They don't attack all species of trees. Duch elm disease killed all the elm trees in large areas of the US. Where's a comparable killer in humans? The bubonic plague is an excellent comparison. In the 14th century the black death wiped out many towns in Europe. Just learning about sanitation and how germs travel has prevented this from happening again. When animals get sick it's common for them to infect the entire herd.

 

Animals have it so much harder than us. Most don't make it to bear young. Let me say that again. Most wild animals that are born do not live long enough to bear young. Which ones die? The ones that are not as fit as the others. Maybe they can't out run the predators, or scurry up a tree. Maybe they can't fight off the diseases. Either way they don't get their genes passed on to the next generation. That's evolution and I say evolution is FAR more prevalent when life and death is a daily battle.

 

Who can really say our gene drift is causing us to evolve faster than wild animals? I don't buy it for a second.

Edited December 9, 2014 by BusaDave9

[chadn737]

So was Darwin completely wrong? His theory explains evolution by natural selection. With natural selection a new species appears roughly every million years (I said roughly so no need to bring up punctuated equilibrium or alligators that have not changed much). I think we agree that survival of the fittest no longer applies to humans but some of you seem to be saying we are evolving faster than ever. How? I get an answer back that it is still possible. I am not saying it's impossible. As I said in my original post:

 

 

To say we can now evolve faster without natural selection must mean that Darwin was wrong and natural selection is not the main driving force of evolution. I ask once again, how could this be? What is the main driving force for evolution? Please don't say intelligent design.

 

1) No Darwin was not "completely wrong". Darwin got a lot of things right. Science typically does not advance in absolutes...at least not in biology...with one side being entirely wrong and the other entirely right. Natural Selection is a critical force of evolution, its just not the only one. There has been 150 years of evolutionary study since Darwin and it has refined and improved his theory. Its proven something wrong...like his method of inheritance...while proving and advancing others, namely natural selection and the truly novel hypothesis of common ancestry.

 

2) And no, we do NOT "agree that survival of the fittest no longer applies to humans". Somebody show me the evidence that natural selection has stopped, that sexual selection has stopped. Just because we have more abundant food and better medicine just means that the selective forces that historically shaped us have weakened or changed. It does not mean that new selective forces have not arose or are in action. Part of the fundamental problem here is that people think that "survival of the fittest" means being the most bad ass atheletic/intelligent creature around able to weather any storm. What it actually means, what it meant to Darwin and all evolutionary biologists is who is reproduces the most.

Of course I know what survival of the fittest is. We're talking genetics here. New genetic traits getting passed on to the next generation to the degree to create a new species. I'm still waiting for anyone to point our any reasons we may be evolving faster than other animals. Sickle cell anemia and malaria are child's play in the non-forgiving wilderness. Do you think wild animals don't have disease? We humans can treat diseases. We are even making great progress with genetic diseases and disorders. As Sunshaker alluded to we may even cure genetic diseases with genetic manipulation, but that would be artificial evolution. How's the animal world coming along finding cures to their diseases? Some plants produce chemicals to fight off parasites. Here in Colorado the bark beetle is killing thousands of square miles of lodgepole pine. They don't attack all species of trees. Duch elm disease killed all the elm trees in large areas of the US. Where's a comparable killer in humans? The bubonic plague is an excellent comparison. In the 14th century the black death wiped out many towns in Europe. Just learning about sanitation and how germs travel has prevented this from happening again. When animals get sick it's common for them to infect the entire herd.

 

Animals have it so much harder than us. Most don't make it to bear young. Let me say that again. Most wild animals that are born do not live long enough to bear young. Which ones die? The ones that are not as fit as the others. Maybe they can't out run the predators, or scurry up a tree. Maybe they can't fight off the diseases. Either way they don't get their genes passed on to the next generation. That's evolution and I say evolution is FAR more prevalent when life and death is a daily battle.

 

Who can really say our gene drift is causing us to evolve faster than wild animals? I don't buy it for a second.

 

Its a factor of population size. In fact, natural selection will be even stronger now because the human population is the largest its ever been. The strength of Natural Selection is in part a factor of population size, being strongest in large populations and weakest in small. Genetic Drift has the opposite relationship to population size. Larger population sizes also means that there will be more new mutations than ever before, as mutations are a factor of time and population size.

[BusaDave9]

 

what it meant to Darwin and all evolutionary biologists is who is reproduces the most.

 

I agree. And I say:

 

 

I say evolution is FAR more prevalent when life and death is a daily battle.

 

Everyone seems to be saying we are still evolving. Okay but no one is convincing me that evolution is taking place nearly as fast as with wild animals.

[chadn737]

 

I agree. And I say:

 

 

Everyone seems to be saying we are still evolving. Okay but no one is convincing me that evolution is taking place nearly as fast as with wild animals.

 

Compared to what animals? All animals have different rates of evolution. In large part, this is a matter of population size. That really is the biggest determinant at work here. It is population genetics 101. If evolution is change over time, then the rate of evolution will be determined by a combination of the various forces driving change. Those forces are 1) Natural Selection, 2) Genetic Drift, 3) Mutation, and 4) Gene Flow (migration, admixture, etc). Since we are talking about humans as a whole, #4 is not really relevant. We aren't interbreeding with chimpanzees or other species that would be a source of gene flow into the population. At best, gene flow would come from viral and bacterial infections. That leaves two major factors at work, natural selection and genetic drift. Both Drift and Selection act upon the variation within a species, they do not create new variation. Mutations do create new variation and its a very strait-forward mathematics to show that in a larger population, there will be more chances for mutations to arise. Humans currently have the largest population in all of history. Our population is much larger than some animals, smaller than others. In comparison to animals like tigers or lions...we have a lot more novel mutations upon which evolution can act, giving rise to new variation phenotypically. Its also basic population genetics that natural selection is most effective in large populations. The decreased population size of some species like tigers, means that natural selection is weaker and genetic drift is stronger. Its one of the major concerns of conservation genetics. At small populations, genetic drift can easily eliminate even beneficial alleles, increase deleterious ones, and send a population into a meltdown scenario.

 

Now if you want compare humans to the populations of some insect species with many billions more individuals...then no, we are not evolving as fast. Compared to rarer and endangered species, we are probably evolving faster.

[CharonY]

It is sad that you approach a topic with preconceptions that apparently are based on conviction, but not on data. For example a recent paper demonstrated that the majority of all existing variants in humans arose within the last few thousand years (Fu et al. 2013; Nature 493, 216–220).

Using our next kin (chimpanzees) it has been estimated that since the split human evolution of acceleration has increased by about 100-fold.As others have noted, this is tightly connected to the massive increase in population size.

 

Interestingly, this is one aspect that Darwin already acknowledged:

 

 

But as variations
manifestly useful or pleasing to man appear
only occasionally, the chance of their appearance will
be much increased by a large number of individuals
being kept; and hence this comes to be of the highest
importance to success.

 

There are many factors influencing the speed of population changes and there is a good reason why evolution in humans is likely to be faster than in many other species.

 

First, human environments changed rapidly. If you look at human history you can easily see that changes in lifestyle, diet (milk, anyone?), city life, disease exposure, migration etc. were rather rapid over the last millenia. Second, the connected increase in population size allowed a much faster response to these selective pressures. This is basically what chadn737 explained earlier.

 

This is the beauty of science. Regardless which preconceptions you may have, there are approaches to test them and, as in this case, provide evidence why they may be wrong. There is no need to believe anything, you just have to follow the data.

 

 

Edit: crossposted, but basically posted similar things.

Edited December 9, 2014 by CharonY

[Phi for All]

 

Everyone seems to be saying we are still evolving. Okay but no one is convincing me that evolution is taking place nearly as fast as with wild animals.

 

What makes "the wild" a more accelerated place for evolution to take place in?

 

There's no set pace for evolution. Nothing is racing to become a particular "thing". Our environment and lifestyle don't remove us from the effects of passing along our genes to our offspring, no matter how unnatural you may consider humans to be.

[Arete]

It should also be noted that a release from stringent selection is often associated with rapid adaptive radiation:

http://www.ncbi.nlm.nih.gov/pubmed/20561138

http://www.jstor.org/stable/10.1086/652433

 

While it may seem intuitive to the layman that reduced selection = reduced evolution, the opposite is actually prevalent.

[BusaDave9]

 

No Darwin was not "completely wrong".

 

You didn't recognize my sarcasm when I asked if Darwin was wrong. I strongly believe Darwin was right when he said evolution is driven by natural selection. That's my main point. Sure there has to be mutation and/or gene drift. But natural selection drives evolution in a certain direction. Natural selection drove squirrel to have teeth that can open nuts, claws that can allow it to scurry up trees.

 

 

 

What makes "the wild" a more accelerated place for evolution to take place in?

 

Because natural selection is the driving force for evolution. I believe it is no longer survival of the fittest for humans. It's survival of everyone. It's amazing what modern science can do.

 

So there are stats that show we are evolving. Okay but I want to understand why.

Lets forget about gene drift. Forget about population size. Forget about mutations. Why? Because these things only introduce variation not a driving force for evolution. Let me explain. Lets say some people get a mutation that causes longer fingers and some people get shorter fingers (yes very hypothetical). Now we have a population with different size fingers. For evolution to take place we need more than random mutations. We need evolutionary direction. Are the people with long fingers more fit? Or less likely to survive? How about the people with short fingers? We have people that are born blind, deaf, or cripple or whatever traits that would surely mean death if it inflicted any wild animal. No so for humans.

Now diseases may cause evolution in humans but not to the degree as it does with wild animals.

Edited December 9, 2014 by BusaDave9

[Phi for All]

Because natural selection is the driving force for evolution. I believe it is no longer survival of the fittest for humans. It's survival of everyone. It's amazing what modern science can do.

 

Two things. First, I'm always at a loss to understand why some people think we could ever do something that wasn't natural. We're part of nature, we just have more intelligence that drives the things we do more than most other animals. I think you're making some kind of meaningless distinction between nature and human civilization. Natural selection still affects us in our cities, or wherever we choose to have the environment host us.

 

Second, someone already mentioned that "fittest" isn't affected necessarily by health or strength or endurance. Fittest just means most well-adapted for an environment or situation. It's always survival of the fittest for us, that doesn't change. Sorry to break it to you, but the guy who can tell a survival story about being sickly as a child but was saved by modern medicine and then went on to graduate college and found his own company supplying medical devices for sick children, well that guy is going to get the girl and be an evolutionary success. Survival of the fittest.

[AndresKiani]

Even though natural selection is indeed the driving force behind evolution. I doubt that we have completely stopped evolving, there may not be drastic sprouts of evolution as was before in our biological history. However, I do believe there are still factors in our environment and interaction as well as technological that have an effect on our species.

 

For example, people are living longer generally.