Future of human evolution? Is there a future?

[Dogdoctor]

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 say there is no natural selection? I just mentioned AIDs as a source of natural selection. Do you think it is not? There will always be selective pressures of some kind or another. How could one predict precisely what is going to happen over the next 50,000 years? There are still natural selection pressures and what I guess you would call "unnatural selections pressures" (societies values in selecting mates and making babies and third world starvation and disease and catastrophic disasters). We may end up a bunch of lazy morons on welfare. I see no reason why we won't change rather than no reason to change as you see.

 

[athon]

It's not my "personal definition". It's Darwin's definition.

For one thing, Darwin said a lot more than that. So you've simplified his own idea down beyond wrong and into 'not even wrong'.

For another thing Darwin isn't the final word on evolution, or even the first word. He is a rather powerful catalyst for the acceptance of the concept and fleshed out the mechanisms beyond what was considered at the time. There is more to evolution than just natural selection, as powerful as it is.

As dr.kitten already pointed out, genetic drift is accepted as a contributory force in evolution. While you are free to use your own definition, it is not the same as that which is used in the literature and therefore you're kind of on your own there.

Lastly, you are being selective in your view of what is 'natural'. Human intervention in genetic change still changes the gene pool. Dogs have evolved into numerous breeds. We have created new species of bacteria. Both under our control. According to your definition this isn't evolution.

You know, if you stopped trying to be so arrogant in your views and actually conceded that you're wrong sometimes you might come away the better for it. Don't you find it even a little odd that so many people here - many with expertise in these fields - point out your definition and factual inconsistencies and errors?

Athon

 

[CapelDodger]

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" ...

Which is why he was a landowner or king. Vikings, yeah? You gotta walk the walk in that sort of society.

 

[EHLO]

I can see where Dustin is coming from here, and my (simple) understanding of evolution is that it is driven by two primary factors - variation and selection. Humans, via our technology, seem to have reached a point where we can control the selection part of this equation, which means that all we're left with is variation.

So my question is: Can genetic variation by itself qualify as evolution?

At the risk of elaborating, it seems that any inter-generational genetic variation is either;

1. benign (ie. has no impact on survival),
2. disadvantageous to survival but allowed to persist by modern society. ie. individual wealth, ethical considerations and medical technology,
3. advantageous to survival but normalised by modern society. ie. technological control of the environment and ethical rejection of "eugenic" style selection mechanisms.

So human evolution will only come about if there is a dramatic shift in the environment (eg. climate, disease etc.) that surpasses our technological abilities, or we engineer it ourselves - which you may or may not classify as "natural".

 

[Dustin Kesselberg]

Why do you say there is no natural selection? I just mentioned AIDs as a source of natural selection. Do you think it is not?

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.

There will always be selective pressures of some kind or another. How could one predict precisely what is going to happen over the next 50,000 years? There are still natural selection pressures and what I guess you would call "unnatural selections pressures" (societies values in selecting mates and making babies and third world starvation and disease and catastrophic disasters). We may end up a bunch of lazy morons on welfare. I see no reason why we won't change rather than no reason to change as you see.

I said that if current trends continued. I can't think of any natural selection pressures on modern society today.

 

[Dustin Kesselberg]

Which is why he was a landowner or king. Vikings, yeah? You gotta walk the walk in that sort of society.

No. There was nothing about viking society that made it so people a few inches taller were richer or became kings. They were taller because they were richer and could afford better nutrition. That's the only reason.

 

[blutoski]

So will humans continue to evolve?

Absolutely.

Are there any natural selection pressures on them that will cause them to evolve into a distinct species than they currently are?

Natural and unnatural. H sap sap will the first terrestrial species to play a role in our own gene pool modification.

I can't think of any.

Of course not! We will only recognize them in retrospect.



Contrary to your above suggestion, mutations propagate quite happily without selection. Since we invented Caesarians, average head size has measureably increased. There is much evidence of recent mutations that have benefits, not the least of which is AIDS resistance. Tay-Sachs is a family of independent mutations that materialised over the last 2,000 years to provide resistance against tuberculosis. More recently, the mutation that causes severe allergy to insect venom has propagated widely, as children who are stung with bees are so much more likely to survive, thanks to access to 911, epipens, and anikits. We all have on average ten-ish de novo mutations, and 99.999% of them are 'silent'.

All of these minor mutations may cloak advantages that will only be evident during a period of external stress. We'll find out which ones are the lucky ones on that day, but until then, we just sit and guess.

 

[blutoski]

So human evolution will only come about if there is a dramatic shift in the environment (eg. climate, disease etc.) that surpasses our technological abilities, or we engineer it ourselves - which you may or may not classify as "natural".

Selection can be internal, though. Consider peacocks: they got caught in a cycle where males with decorative plumage mated with females who liked decorative plumage, and this genetic kowinkidink concentrated until it became the schmozzle it is today.

The second factor is that even without an external change, a mutation may create an internal advantage in fecundity and eventually dominate the overall population. Either through sexual selection as mentioned above, or through intraspecies competition.

The third element is genetic drift - some mutations may be common, but suppressed by our current technological limitations. A change to our cultural/technological situation may simulate an 'external' change, and some suppressed genes may find themselves quite abundant. I mentioned insect venom allergies in a previous post - this is a good example.

 

[Dustin Kesselberg]

The second factor is that even without an external change, a mutation may create an internal advantage in fecundity and eventually dominate the overall population. Either through sexual selection as mentioned above, or through intraspecies competition.

With modern technology still existing, how could this happen? Give me a hypothetical example.

 

[athon]

I can see where Dustin is coming from here, and my (simple) understanding of evolution is that it is driven by two primary factors - variation and selection. Humans, via our technology, seem to have reached a point where we can control the selection part of this equation, which means that all we're left with is variation.

Evolution is a numbers game; the genes which proliferate further across generations determine the nature of the organism and the ability for each population to interbreed with other gene pools. Variation, whether it results from point mutation, genetic combinations, chromosomal changes or transposon exchanges (to name but a few ways variation can occur) will always arise within a gene pool. The question is whether the variations bleed out into a background static or come to dominate the majority of individuals within a population.

Two populations separated from one another geographically yet facing similar selection pressures will, over time, speciate solely due to genetic drift. Humans have no geographical isolation, however genetic drift will still isolate the species from ancestoral populations over time.

So my question is: Can genetic variation by itself qualify as evolution?

I'm not sure what you mean by this. Evolution is the progress of genetic variation over time. Speciation is the genetic isolation of populations from one another, preventing them from exchanging genetic variation.

At the risk of elaborating, it seems that any inter-generational genetic variation is either;

1. benign (ie. has no impact on survival),
2. disadvantageous to survival but allowed to persist by modern society. ie. individual wealth, ethical considerations and medical technology,
3. advantageous to survival but normalised by modern society. ie. technological control of the environment and ethical rejection of "eugenic" style selection mechanisms.

True. The environment is more controlled for humans, and proliferation of genes through a population - where it once relied on the competition of numbers of offspring - now relies less on a 'survival of the fittest' strategy. Fitness in human environments does not automatically equate greater proliferation of one's own genes. Genetic drift, however, over a long period of time will see some change.

My view is that with current technological progress, we will eventually manipulate our genes with increasing confidence to control the genetic change over time. While these are novel selection pressures (intentional, indeed almost Lamarckian in a way), they are still evolutionary.

So human evolution will only come about if there is a dramatic shift in the environment (eg. climate, disease etc.) that surpasses our technological abilities, or we engineer it ourselves - which you may or may not classify as "natural".

That's about the sum of it. Of course, technology - as it is - is unlikely to stagnate. If it does, there are environmental changes which will inevitably surpass current progress. If it continues to improve, the likelihood of environmental shifts impacting on us will decrease, yet out ability to change our own genetic variation will continue to increase. Either way, a form of evolution will continue to occur.

Athon

 

[Earthborn]

I think that one of the most ridiculous misconceptions people have about evolution is that "natural selection" necessarily involves dying. That it is an all or nothing affair; either you live and reproduce, or you die an early death.

It doesn't work that way. Natural selection is about the chances of reproduction. Dying obviously does reduce that chance to zero, but other influences also have a selective effect that does not require an individual organism to die before having a chance to reproduce itself.

As long as there are individual differences in fertility or attractiveness or desire to reproduce, there will be natural selection and therefore evolution. Even if one day everyone has the exact same life expectancy.

 

[Ceritus]

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



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



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?

Technology played a role, but if hawking was an ass who was an idiot what were his chances of reproducing?

Or what if he happened to be gay, what were his chances of producing offspring with his genetics instead of his partners?

 

[Ceritus]

The more and more I read what you type dustin you seem to hate your own species, which is fine, but don't think that it makes you more correct in your arguments.

I personally would love to have a panda fur coat, I could sell it for a buttload or I could wear it out and about and bask in the rarity of it all. I even love to eat animals and hopefully in the near future I will have time to go out hunting as well.

Perhaps I am just a preditor or greedy. I tell you one thing though I do love humans but some more than others. Like my wife and daughter for example I would gladly sacrifice you or any stranger if it would ensure their safety and comfort without direct consequence to me or them. As I would gladly kill all the pandas for the comfort and safety of you or a stranger if it were without consequence to my family or I. If saving the panda species were simple and not that costly I would be fine with it, to each his own right? But if it were fairly costly I would much rather spend that money giving the ability to produce clean water to many third world countries if the extinction of the panda since they are negligable to human survival.

 

[Soapy Sam]

Evolution is a word. It means what we define it to mean.

There are over 6 billion humans alive now. Genetic bottlenecks or not, that's a lot of potential variants.
Of course we are missing a place for one group to be isolated.
Fortunately, we don't need one. Humans isolate genepools culturally. Are there 6 billion Ashkenazim in the world? Nope. Are they selecting for a different mixture of allelles than the less than 6 billion Bushmen in the Kalahari? Yep.
Then there's the question of parasites. Have human parasites stopped evolving? Not that I've heard. So those of us likely to experience them had darn well better not have stopped either.
Some of those 6 billion people will be more resistant to the new forms of Tuberculosis, which may give them a differential edge.

As for speciation. Forget bloody speciation. The whole big deal about "Origin of Species" was a Victorian obsession. We know where species come from: We define them. Evolution can and does happen all the time without causing speciation.

But evolution has probably never happened before in a population of 6 billion closely related mammals, with a global range. The results may be different from what we see in the fossil record. Which is interesting, but unsurprising.

And there's always Mars. We're going there one day. You better believe we'll evolve.

 

[Ceritus]

To get back at the human evolution thing.

Sickle cell anemia is a perfect example of human evolution. Allowing many who would have died of malaria prior to an age for reproduction.

 

[Kaylee]

Of course not! We will only recognize them in retrospect.

Is it possible that even over just the past couple of thousand years our species have measurably evolved in social intelligence without our acknowledging this?

Over the past two thousand years our forms of govt. have become more democratic and in many societies we share power more equally within marriages. We have far fewer slaves now than in the past. I don't think that this would have been possible without an increase in our species' social intelligence.

Our "evolution" in our social institutions such as govt. and marriage changes the selection pressures and the types of people who will have increased chances of reproduction which in turn causes not only our species to evolve but also our social institutions in a continuing circle of change and evolution.

 

[EHLO]

So my question is: Can genetic variation by itself qualify as evolution?

I'm not sure what you mean by this. Evolution is the progress of genetic variation over time. Speciation is the genetic isolation of populations from one another, preventing them from exchanging genetic variation.

I think we're on the same page here, but just to clarify; the *progress* of genetic variation surely comes about from the selection pressures applied to the population of variants. If there are no selection pressures then surely all you end up with is a large population of increasing variation? It may be a subtle difference, but that does not seem to be the same as evolution to me.

Having said that, it seems that un-capped variation in a population would itself eventually impose a selection pressure, so maybe I'm just chasing my tail.

 

[EHLO]

Evolution is a word. It means what we define it to mean.

Agreed

There are over 6 billion humans alive now. Genetic bottlenecks or not, that's a lot of potential variants.
Of course we are missing a place for one group to be isolated.
Fortunately, we don't need one. Humans isolate genepools culturally. Are there 6 billion Ashkenazim in the world? Nope. Are they selecting for a different mixture of allelles than the less than 6 billion Bushmen in the Kalahari? Yep.
Then there's the question of parasites. Have human parasites stopped evolving? Not that I've heard. So those of us likely to experience them had darn well better not have stopped either.
Some of those 6 billion people will be more resistant to the new forms of Tuberculosis, which may give them a differential edge.

But humans don't have to adapt by evolutionary means to these threats. We have, and will continue to develop, technological means to overcome biological and environmental pressures.

As for speciation. Forget bloody speciation. The whole big deal about "Origin of Species" was a Victorian obsession. We know where species come from: We define them. Evolution can and does happen all the time without causing speciation.

But evolution has probably never happened before in a population of 6 billion closely related mammals, with a global range. The results may be different from what we see in the fossil record. Which is interesting, but unsurprising.

And there's always Mars. We're going there one day. You better believe we'll evolve.

I don't get this - you think we'll send a bunch of astronauts to Mars and see which ones have the right genetic variations to allow them to survive?

(Forgive me if that last comment was intended to be facetious)

 

[athon]

I think we're on the same page here, but just to clarify; the *progress* of genetic variation surely comes about from the selection pressures applied to the population of variants. If there are no selection pressures then surely all you end up with is a large population of increasing variation? It may be a subtle difference, but that does not seem to be the same as evolution to me.

Having said that, it seems that un-capped variation in a population would itself eventually impose a selection pressure, so maybe I'm just chasing my tail.

This is an argument I used to have a lot with my housemate. And I had your view; a population with zero pressure will have zero change. She claimed that even genetic drift would deliver enough differences over time.

I've changed my stance somewhat; there is never zero selection pressure, but it doesn't need to be massive for genetic drift to be nudged one way or another. So even a single population which has a large gene flow will have subtle changes in the proportions of genotypes over time. This is demonstrated on smaller scales with bacteria, for instance. The prevalence of particular gene combinations will change slightly with time. Humans might not look dramatically different in a few tens of millions of years (excluding genetic engineering), but I'd be fairly certain that the genetic combinations and differences due to genetic drift would have speciated them from us.

Athon

 

[Cuddles]

With modern technology still existing, how could this happen? Give me a hypothetical example.

What is your obsession with technology? If anything, technology is now one of the biggest, if not the biggest, influence on selection. Thousands of years ago people were selected for their ability to hunt deer, or whatever. Now they are selected for their ability to use computers and other things. Surely you have to admit that a high up, tech savvy executive has more chance of reproducing than, say, a 50IQ bin man with a mortal fear of computers. Natural selection refers to all selective pressures from the environment. Technology is now part of our environment. Far from eliminating selection, technology is now part of it, although the pressure will be in a different direction from that on cavemen.

The only interesting thing that you are almost getting at is the rate of change of selective pressure. In the past, pressure would be in the same direction for hundreds of thousands of years, leading to constant development in certain directions for certain features. With a rapid rate of change of society and technology the direction of the selective pressure also changes and we might no longer be pushed to develop as far or as fast in a single direction. This does not mean evolution has stopped, or that selection no longer exists, but it does mean that we should not necessarily expect to see humans evolve towards a distant goal, since what is good for one generation might not be good for the next, and selection might push us right back to where we started.

Your problem seems to be that you seem to consider evolution as directed. Humans are evolving and always will be, but we are not evolving towards anything. This can make it seem as though evolution is not happening because we cannot see what is happening at all. Take giraffes. Millions of years ago they looked something like horses. There was pressure on them to be taller to reach the top of trees, so they got longer necks. If the trees had changed height every generation the pressure would not have been constant. If one generation needs long necks and the next needs short ones, over millions of years neck length will stay about the same. Evolution will still have been happening at every point, and the selective pressure is always there, but overall the giraffes appear not to be evolving and look a lot less silly. The same is true for humans. Whether we are evolving in a constant direction or not, there are always some people who have more children than others and who pass on the tendency to have more children. That is evolution.