Future of human evolution? Is there a future?

[Dustin Kesselberg]

Over the past 500,000 years humans have appeared from previous species and have evolved via natural selection into what we see today. Natural selection selected out the harmful or non-beneficial traits in our genome that were expressed and spread traits that aided us in our environment. However in order for this to occur, humans must be subjected to the "pressure" from their environment for natural selection to occur. When there are no pressures driving natural selection, then it won't occur and evolution is at a stand still. After all, why does a species need to evolve to fit it's environment when it already fits it?

In modern society nearly all past selection pressures are removed with modern medicine and technology. Someone today like Stephen Hawking for instance would not of survived even a few months after he contracted his illness had he lived 20,000 years ago. Stephen Hawking however due to modern medicine and technology lived and had children and grandchildren. This happens frequently in many people. People who are alive today with genetic defects or illnesses might of easily died had they lived 20,000 years ago. However today, they can live and reproduce.

Natural selection is still occurring in some populations, notably in Africa where people who are immune to catching the HIV virus are being selected out and have a clear advantage over their peers who all die from Aids. It's possible that if no cure for HIV is ever found, within 10,000 years the descendent's of modern Africans might be totally immune to aids. However most likely by that time we will have developed a cure for HIV and Aids and likely those living in Africa will have dispersed throughout the world and will be less likely to catch HIV than they currently are.

Some argue that in modern society natural selection still occurs, that people who are able to accumulate money are more prosperous and live longer and have more children. However the fact is, on average, people who are poorer tend to have more children than people who are richer. So this really can't be said to have any affect on human evolution.

So will humans continue to evolve? Are there any natural selection pressures on them that will cause them to evolve into a distinct species than they currently are? I can't think of any.

 

[Floyt]

Current trends say that people in 200 years will tend to be coffee-skinned 2-meter-giants with (to our sensibilities) rather neotenic heads. Just because the buffer of culture prevents much of the "culling" kind of selection, doesn't mean none is going on; it's just less spectacular. Also, you are talking about a very short timeframe so far. Give bacteria some time to come up with a couple nice resistant new morphs, and there may well be another Black Death type of triage to catch up on some of the weeding out.

 

[Dogdoctor]

The aids epidemic is putting a bit of pressure on our gene pool. But you're talking about a species change which would require more years. We haven't stopped evolving so eventually we will become another species but it takes time.

 

[Dustin Kesselberg]

Current trends say that people in 200 years will tend to be coffee-skinned 2-meter-giants with (to our sensibilities) rather neotenic heads. Just because the buffer of culture prevents much of the "culling" kind of selection, doesn't mean none is going on; it's just less spectacular. Also, you are talking about a very short timeframe so far. Give bacteria some time to come up with a couple nice resistant new morphs, and there may well be another Black Death type of triage to catch up on some of the weeding out.

Coffee skinned 2 meter giants? Humans aren't growing taller genetically. Some nations are simply getting taller due to improved nutrition.

As far as kin tone goes, I don't see how mixing the genetics could be called "Evolution". Where's the natural selection there?

 

[Dustin Kesselberg]

The aids epidemic is putting a bit of pressure on our gene pool. But you're talking about a species change which would require more years. We haven't stopped evolving so eventually we will become another species but it takes time.

What species? And how? Evolution occurs per natural selection. If there is no natural selection then there's no evolution. Let's assume 50,000 years. Let's assume society works the way it still does but with increasing cures for diseases and disabilities. What natural selection pressures could there be? Given current trends, humans simply won't change much anymore, Especially into a new "species". There's no "need".

 

[EternalSceptic]

Some argue that in modern society natural selection still occurs, that people who are able to accumulate money are more prosperous and live longer and have more children. However the fact is, on average, people who are poorer tend to have more children than people who are richer. So this really can't be said to have any affect on human evolution.

So will humans continue to evolve? Are there any natural selection pressures on them that will cause them to evolve into a distinct species than they currently are? I can't think of any.

Maybe you have a look at memetics?

 

[Dustin Kesselberg]

Maybe you have a look at memetics?

Aren't 'memes' simply traditions and beliefs etc?

 

[Jaggy Bunnet]

What species? And how? Evolution occurs per natural selection. If there is no natural selection then there's no evolution. Let's assume 50,000 years. Let's assume society works the way it still does but with increasing cures for diseases and disabilities. What natural selection pressures could there be? Given current trends, humans simply won't change much anymore, Especially into a new "species". There's no "need".

Why do you assume there is no natural selection? What about sexual selection? Do you think that people with disabilities will have the same number of children as those without? If not, then they ARE subject to natural selection.

 

[EternalSceptic]

What species? And how? Evolution occurs per natural selection. If there is no natural selection then there's no evolution. Let's assume 50,000 years. Let's assume society works the way it still does but with increasing cures for diseases and disabilities. What natural selection pressures could there be? Given current trends, humans simply won't change much anymore, Especially into a new "species". There's no "need".

Just leave the "need" out. It does not work this way. The modification comes first, and that one which causes more offspring under the given conditions will dominate.

I am thinking of memetics here as a part of the picture. People whos behavior is more appreciated by their possible partners might have more offspring(statistically) and therefor begin to dominate. Sex appeal is not an objective property and not only a question of the bodys features, it is a pretty complex combination of properties and behavior (and fashion as well).

 

[Dustin Kesselberg]

Why do you assume there is no natural selection? What about sexual selection? Do you think that people with disabilities will have the same number of children as those without? If not, then they ARE subject to natural selection.

I've never seen anything to suggest that people with genetic disabilities have less children than those without them.

I don't even know if sexual selection occurs. Pretty people generally have children with other pretty people and ugly people have children with other ugly people. If sexual selection was rotting out the ugly then we wouldn't have so many ugly people still in the world. So I don't think that's happening either.

 

[EternalSceptic]

Aren't 'memes' simply traditions and beliefs etc?

AFAIK everything we learn by copying. I think you can find a lot of information about them at www.susanblackmore.co.uk/memetics/

And yes, traditions, beliefs etc are memes or whole complexes of memes. Their influence on human evolution seems to be caused by, among others, having influence on the sexual attraction and the grouping of people.

AFAICS the whole thing is still a hypothesis, but IMO a promising one.

 

[Dustin Kesselberg]

Just leave the "need" out. It does not work this way. The modification comes first, and that one which causes more offspring under the given conditions will dominate.

The mutations come first, but they generally aren't proliferated unless they provide advantages. So the "need" comes into play.

I am thinking of memetics here as a part of the picture. People whos behavior is more appreciated by their possible partners might have more offspring(statistically) and therefor begin to dominate. Sex appeal is not an objective property and not only a question of the bodys features, it is a pretty complex combination of properties and behavior (and fashion as well).

I don't know if this has any affect on human evolution.

 

[Floyt]

Coffee skinned 2 meter giants? Humans aren't growing taller genetically. Some nations are simply getting taller due to improved nutrition.

That is the cause, but the adaptation is perfectly inheritable. The population of, e.g., Austria would not after one generation that grew up with bad nourishment again have offspring that could wear these cute midget-sized suits of mail from the 12th century. That would take a similarly prolonged process of reducing average size over many generations.

As far as kin tone goes, I don't see how mixing the genetics could be called "Evolution". Where's the natural selection there?

Natural selection does not mean "killing off the less well adapted" (although that is often the outcome), but "advantaging the well adapted". Global spreading and racial mixing being a currently successful cultural trait of humanity, an averaged skin tone would be the expected manifestation of the success of this behaviour.

 

[Dustin Kesselberg]

That is the cause, but the adaptation is perfectly inheritable. The population of, e.g., Austria would not after one generation that grew up with bad nourishment again have offspring that could wear these cute midget-sized suits of mail from the 12th century. That would take a similarly prolonged process of reducing average size over many generations.

It has nothing to do with genetics. It has to do with nutrition. An Austrian that grew up with the same nutrition that a 12th century knight might of had would likely be the size of your average 12th century knight.

Austrians are taller today because of their improved nutrition.

Natural selection does not mean "killing off the less well adapted" (although that is often the outcome), but "advantaging the well adapted". Global spreading and racial mixing being a currently successful cultural trait of humanity, an averaged skin tone would be the expected manifestation of the success of this behaviour.

The mixed skin tone would be a "side effect" of the behavior. Not a result of natural selection itself.

 

[Floyt]

It has nothing to do with genetics. It has to do with nutrition. An Austrian that grew up with the same nutrition that a 12th century knight might of had would likely be the size of your average 12th century knight.

That's a false absolute. A good rule of thumb for body size in humans is that it's 90% controlled by heredity, 10% by environmental causes. While bad nutrition might be a cause for less growth in height, an ill-nourished child by "modern parents" would still tend to be larger than a well-nourished medieval one. It would take a prevalence of small progenitors in the population (arrived at through successive generations) to get back to "average medieval size".

Austrians are taller today because of their improved nutrition.

Yes, and they are not going to lose it in one generation. It sticks, by now; it's inheritable. Of course that does not mean irreversible.

The mixed skin tone would be a "side effect" of the behavior. Not a result of natural selection itself.

It would be an indicator (that is not fitness-relevant in itself) of a successful (fitness-relevant) trait.

 

[Ocelot]

Of course natural selection is still occuring. You said it yourself. 20,000 years ago someoen like Stephen Hawking would have a far shorter life expectancy. Typically ALS strikes later in life but Hawkins was diagnosed with it before he married and had kids. Were it not for the miricles of modern medicine then he would have been unlikley to sire either of his forst two kids and certainly no his third. ALS probably has a genetic component (as well as environmental risk factors) by managing our own environment we have changed the selction pressures that select against ALS and as Proffessor Hawkins' example shows this has increased the liklihood of those genes being passed on. Not only was Stephen able to sire these children but his condition has not impeded him working to provide financial security to their upbringing and furthmore the edification of the human race. It has even been said that his condition played no small part in the brilliance of his work: There's little else he can do but think.

So, selection pressures have changed due to environmental change brought about by our own ability to affect our environment. These selction pressures cannot help but affect the gene pool. Certain diseases which thousands of years ago might be lethal are now cured or easliy managed. They are therefore more prevalent. When environment is static then natural selection reachis a statis. Our modern science and technology has altered selection pressure fundamentally from our hunter gatherer statis. We should therefore be evolving faster than at any time in the last few hundred thousand years.

 

[Dustin Kesselberg]

That's a false absolute. A good rule of thumb for body size in humans is that it's 90% controlled by heredity, 10% by environmental causes. While bad nutrition might be a cause for less growth in height, an ill-nourished child by "modern parents" would still tend to be larger than a well-nourished medieval one. It would take a prevalence of small progenitors in the population (arrived at through successive generations) to get back to "average medieval size".

Do you have any evidence for this? I have plenty of evidence suggesting that the difference in heights in the past few thousand years is due to nutrition and not genetics. Take viking bones for instance. If you look at the average viking then he'd be about 5'6" tall. Yet the landowner or king was usually around 5'11"-6'0", the average height in modern Scandinavia.

http://www.j-bradford-delong.net/articles_of_the_month/pdf/w8542.pdf

Yes, and they are not going to lose it in one generation. It sticks, by now; it's inheritable. Of course that does not mean irreversible.

Raise an Austrian in Ethiopia who would genetically grow to be 6'0" with proper nutrition and he'll be a lot shorter.

It would be an indicator (that is not fitness-relevant in itself) of a successful (fitness-relevant) trait.

I don't quite understand what you're saying here.

 

[Dustin Kesselberg]

Of course natural selection is still occuring. You said it yourself. 20,000 years ago someoen like Stephen Hawking would have a far shorter life expectancy. Typically ALS strikes later in life but Hawkins was diagnosed with it before he married and had kids. Were it not for the miricles of modern medicine then he would have been unlikley to sire either of his forst two kids and certainly no his third. ALS probably has a genetic component (as well as environmental risk factors) by managing our own environment we have changed the selction pressures that select against ALS and as Proffessor Hawkins' example shows this has increased the liklihood of those genes being passed on. Not only was Stephen able to sire these children but his condition has not impeded him working to provide financial security to their upbringing and furthmore the edification of the human race. It has even been said that his condition played no small part in the brilliance of his work: There's little else he can do but think.

The fact that Hawkings lived and was able to marry and reproduce is due to technology, not "natural selection".

Certain diseases which thousands of years ago might be lethal are now cured or easliy managed. They are therefore more prevalent.

How are diseases that are cured by modern medicine more prevalent?

When environment is static then natural selection reachis a statis. Our modern science and technology has altered selection pressure fundamentally from our hunter gatherer statis. We should therefore be evolving faster than at any time in the last few hundred thousand years.

Simple change in environment doesn't cause natural selection. "Selection pressures" do. What selection pressures do we have in modern society that could cause us to make substantial changes in our genomes?

 

[athon]

The human population is genetically not all that diverse. Following a bottle-neck event in the relatively recent past, we're all fairly closely related. Such a limitation in variation coupled with a constricted population (can't get more constricted than an island called 'Earth') we have very little in the way of speciation pressure. However, this won't prevent a gradual change; it will only slow it.

Genetic drift occurs as a non-selective pressure. It is the random static of change which occurs across generations on which greater selection pressures occur. Given enough time, small variations will arise within a population, so long as the phenotype remains viable within its environment.

To see where potential changes could occur, we need to look at a) relatively isolated gene pools and b) pressures on genetic proliferation.

Gene pool isolation is less a result of geography these days (with technology in transport), but still occurs to some extent with culture. An example is the higher prevalence of Tay Sachs amongst Jewish populations. Those of similar cultural backgrounds have a higher preference for breeding together.

Of course, with time the gene flow across such pools would mean there was little chance of speciation of any sort. It would simply allow for certain variations to occur and spread through the rest of the population. As such, the human species would continue to have a subtle change in variation with unpredictable 'direction' as such. In other words, it would be impossible to describe homo sapien's distant evolutionary future if current conditions remained the same.

Several things make this unlikely. One is that the environment is unlikely to remain so stable for so long. Across wide gaps of time we would see substantial changes, challenging our ability to modify our surroundings. While humanity would probably not die out, there would be fluctuations in our population which could produce relatively isolated pockets.

However that would be assuming that our technology does not continue to progress. Assuming it does, our ability to modify our environment would supersede such pressures, as well as our ability to modify ourselves. We would indeed be able to direct our own evolution, as such.

Given isolation through other means, such as space travel, it might again open possibilities for non-directed evolution to take place. Yet I would think that if we have capabilities of isolating ourselves so effectively through this sort of technology, that same technology would be advanced enough to again have great control over our physiology and genetics.

In short, if something was to restrict our technological progress in the face of future environmental change, then we would continue to be affected by the traditional pressures which have shaped life until now. If not, we will introduce novel pressures (such as our own modelling) in the future.

The answer is yes, humans will continue to evolve.

Athon

 

[Dustin Kesselberg]

Genetic drift occurs as a non-selective pressure. It is the random static of change which occurs across generations on which greater selection pressures occur. Given enough time, small variations will arise within a population, so long as the phenotype remains viable within its environment.

Those small variations won't be evolution. Genetic drift isn't evolution.

Of course, with time the gene flow across such pools would mean there was little chance of speciation of any sort. It would simply allow for certain variations to occur and spread through the rest of the population. As such, the human species would continue to have a subtle change in variation with unpredictable 'direction' as such. In other words, it would be impossible to describe homo sapien's distant evolutionary future if current conditions remained the same.

Small variations caused by genetic drift won't result in the large changes we're talking about for speciation to occur. There needs to be selectional pressures.

Several things make this unlikely. One is that the environment is unlikely to remain so stable for so long. Across wide gaps of time we would see substantial changes, challenging our ability to modify our surroundings. While humanity would probably not die out, there would be fluctuations in our population which could produce relatively isolated pockets.

Unless humans somehow forget to build boats, I find this just as unlikely.

However that would be assuming that our technology does not continue to progress. Assuming it does, our ability to modify our environment would supersede such pressures, as well as our ability to modify ourselves. We would indeed be able to direct our own evolution, as such.

If we are able to direct it then it wouldn't be "Evolution" in the strictest sense.

In short, if something was to restrict our technological progress in the face of future environmental change, then we would continue to be affected by the traditional pressures which have shaped life until now. If not, we will introduce novel pressures (such as our own modelling) in the future.

What pressures are there currently that could cause speciation? There are none.

The answer is yes, humans will continue to evolve.

I don't see how your post supports this contention.