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Is human evolution finally over?


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For those who dream of a better life, science has bad news: this is the best it is going to get. Our species has reached its biological pinnacle and is no longer capable of changing.

That is the stark, controversial view of a group of biologists who believe a Western lifestyle now protects humanity from the forces that used to shape Homo sapiens.

'If you want to know what Utopia is like, just look around - this is it,' said Professor Steve Jones, of University College London, who is to present his argument at a Royal Society Edinburgh debate, 'Is Evolution Over?', next week. 'Things have simply stopped getting better, or worse, for our species.'

This view is controversial, however. Other scientists argue that mankind is still being influenced by the evolutionary forces that created the myriad species which have inhabited Earth over the past three billion years.

'If you had looked at Stone Age people in Europe a mere 50,000 years ago, you would assume the trend was for people to get bigger and stronger all the time,' said Prof Chris Stringer, of the Natural History Museum, London. 'Then, quite abruptly, these people were replaced by light, tall, highly intelligent people who arrived from Africa and took over the world. You simply cannot predict evolutionary events like this. Who knows where we are headed?'

Some scientists believe humans are becoming less brainy and more neurotic; others see signs of growing intelligence and decreasing robustness, while some, like Jones, see evidence of us having reached a standstill. All base their arguments on the same tenets of natural selection.

According to Darwin's theory, individual animals best suited to their environments live longer and have more children, and so spread their genes through populations. This produces evolutionary changes. For example, hoofed animals with longer necks could reach the juiciest leaves on tall trees and therefore tended to eat well, live longer, and have more offspring. Eventually, they evolved into giraffes. Those with shorter necks died out.

Similar processes led to the evolution of mankind, but this has now stopped because virtually everybody's genes are making it to the next generation, not only those who are best adapted to their environments.

'Until recently, there were massive differences between individuals' lifespans and fecundity,' said Jones. 'In London, the death rate outstripped the birth rate for most of the city's history. If you look at graveyards from ancient to Victorian times, you can see that a half of all children died before adolescence, probably because they lacked genetic protection against disease. Now, children's chances of reaching the age of 25 have reached 98 per cent. Nothing is changing. We have reached stagnation.'

In addition, human populations are now being constantly mixed, again producing a blending that blocks evolutionary change. This increased mixing can be gauged by calculating the number of miles between a person's birthplace and his or her partner's, then between their parents' birthplaces, and finally, between their grandparents'.

In virtually every case, you will find that the number of miles drops dramatically the more that you head back into the past. Now people are going to universities and colleges where they meet and marry people from other continents. A generation ago, men and women rarely mated with anyone from a different town or city. Hence, the blending of our genes which will soon produce a uniformly brown-skinned population. Apart from that, there will be little change in the species.

However, such arguments affect only the Western world - where food, hygiene and medical advances are keeping virtually every member of society alive and able to pass on their genes. In the developing world, no such protection exists.

'Just consider Aids, and then look at chimpanzees,' says Jones. 'You find they all carry a version of HIV but are unaffected by it.

'But a few thousand years ago, when the first chimps became infected, things would have been very different. Millions of chimps probably died as the virus spread through them, and only a small number, which possessed genes that conferred immunity, survived to become the ancestors of all chimps today.

'Something very similar could soon happen to humans. In a thousand years, Africa will be populated only by the descendants of those few individuals who are currently immune to the Aids virus. They will carry the virus but will be unaffected by it. So yes, there will be change there all right - but only where the forces of evolution are not being suppressed.'

However, other scientists believe evolutionary pressures are still taking their toll on humanity, despite the protection afforded by Western life. For example, the biologist Christopher Wills, of the University of California, San Diego, argues that ideas are now driving our evolution. 'There is a premium on sharpness of mind and the ability to accumulate money. Such people tend to have more children and have a better chance of survival,' he says. In other words, intellect - the defining characteristic of our species - is still driving our evolution.

This view is countered by Peter Ward, of the University of Washington in Seattle. In his book, Future Evolution, recently published in the US by Henry Holt, Ward also argues that modern Western life protects people from the effects of evolution. 'I don't think we are going to see any changes - apart from ones we deliberately introduce ourselves, when we start to bio-engineer people, by introducing genes into their bodies, so they live longer or are stronger and healthier.'

If people start to live to 150, and are capable of producing children for more than 100 of those years, the effects could be dramatic, he says. 'People will start to produce dozens of children in their lifetimes, and that will certainly start to skew our evolution. These people will also have more chance to accumulate wealth as well. So we will have created a new race of fecund, productive individuals and that could have dramatic consequences.

'However, that will only come about when we directly intervene in our own evolution, using cloning and gene therapy. Without that, nothing will happen.'

Stringer disagrees, however. 'Evolution goes on all the time. You don't have to intervene. It is just that it is highly unpredictable. For example, brain size has decreased over the past 10,000 years. A similar reduction has also affected our physiques. We are punier and smaller-brained compared with our ancestors only a few millennia ago. So even though we might be influenced by evolution, that does not automatically mean an improvement in our lot.'

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I am astounded that this remark could come from a professional biologist.

 

If you look at graveyards from ancient to Victorian times, you can see that a half of all children died before adolescence, probably because they lacked genetic protection against disease. Now, children's chances of reaching the age of 25 have reached 98 per cent. Nothing is changing. We have reached stagnation.'

 

He asserts in the opening sentence that the children who did not survive to an age at which they could reproduce lacked the genetic protection against disease. Now we provide that through medicines and preventive actions. Cleary the genetic character of the population has changed dramatically, yet he asserts "Nothing is changing". Well, duh, please refer to the undergraduate notes you used to hand out to your students. Find the bit that defines evolution as the change of allele frequency in a population.

 

Just astounding.

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The author of the article you posted seems ignorant that data from the Framingham heart study uneviocally proves that humans are still evolving, quite dramatically when some traits, such as blood pressure and LDL cholestorol.

 

"Our aims were to demonstrate that natural selection is operating on contemporary humans, predict future evolutionary change for specific traits with medical significance, and show that for some traits we can make short-term predictions about our future evolution. To do so, we measured the strength of selection, estimated genetic variation and covariation, and predicted the response to selection for women in the Framingham Heart Study, a project of the National Heart, Lung, and Blood Institute and Boston University that began in 1948. We found that natural selection is acting to cause slow, gradual evolutionary change. The descendants of these women are predicted to be on average 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 than they would in the absence of evolution. Selection is tending to lengthen the reproductive period at both ends."

 

 

http://www.pnas.org/content/107/suppl.1/1787.short

Edited by Arete
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Actually, it's even stupider than that.

it says "For those who dream of a better life, science has bad news: this is the best it is going to get. Our species has reached its biological pinnacle and is no longer capable of changing.".

 

I'm sat reading this: I'm an adult. What is evolution going to do to change me?

Obviously nothing because I'm stuck with the DNA that I was born with.

 

So whether evolution is going full steam ahead; stalled, or even in reverse, it's not going to make any difference to me. I can dream of a better life and who knows? maybe I will get one- but evolution won't provide it.

 

When I saw that bit I thought "this has been written by a journalist seeking to sensationalise a non-story.

That's why I checked and found where it had been copied from.

 

Vignesh Loganathan needs to learn not to plagiarise stuff and also not to plagiarise rubbish.

 

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Unless we start cloning ourselves as our exclusive means of reproduction, and nobody ever dies without a clone made from their DNA replacing them, then evolution is still taking place.

 

Well, or if we stop reproducing altogether and just die out. I suppose we'd stop evolving then, too.

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You don't think living on another planet would have anything to do with our biological evolution???

 

EVERYTHING in a given environment, including the people in it drive one's evolution.

Being in a different environment certainly changes the selection pressures operating on a population, but going into space isn't evidence that evolution is happening. Evolution would be taking place whether we were flying to Mars or stuck living in mud huts. You listed a bunch of examples of human progress, but human progress and human evolution aren't the same thing and don't require one another to exist.
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I believe it's pertinent to make clear the difference between "evolution" and "natural selection," first of all. Next, if we're discussing evolution (and not n.s.) then are we focusing only on that which occurs biologically or also the more colloquial sense of evolution of the human condition and society? As far as I'm aware, all life evolves... DNA will constantly be mutated, genetic variation will continue, etc. However, it is my opinion that the "next step" for human evolution is in us grabbing the reins and directing it ourselves through transhumanist pursuits such as biotechnology, cybernetics, nanotechnology, genetic engineering, etc. I'd also like to thank Arete for posting some very interesting research above.

Edited by Michael Kovich
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I believe it's pertinent to make clear the difference between "evolution" and "natural selection," first of all. Next, if we're discussing evolution (and not n.s.) then are we focusing only on that which occurs biologically or also the more colloquial sense of evolution of the human condition and society? As far as I'm aware, all life evolves... DNA will constantly be mutated, genetic variation will continue, etc. However, it is my opinion that the "next step" for human evolution is in us grabbing the reins and directing it ourselves through transhumanist pursuits such as biotechnology, cybernetics, nanotechnology, genetic engineering, etc. I'd also like to thank Arete for posting some very interesting research above.

The topic, for all the misunderstanding of the subject, is still pretty clearly about biological evolution.

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As long as humans are reproducing with variation evolution goes on...

Agreed...but the degree to which that variation occurs and 'changes' would have everything to do with varying environmental demands, right?

 

Being in a different environment certainly changes the selection pressures operating on a population, ... examples of human progress, but human progress and human evolution aren't the same thing and don't require one another to exist.

Agreed, and I would argue that progress IS evolution. :)

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  • 4 weeks later...

Just a thought. But what entity actually evolves? An individual or a gene pool?

 

Mars colonization is a great example, actually. There's almost no breeding with the populations on Earth (it's far too expensive for round-trip travel). That alone would eventually lead to speciation. Then there's the dramatic differences in the environment. Yeah, when humanity spreads among the stars, it will be humanities among the stars.

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Mars colonization is a great example, actually. There's almost no breeding with the populations on Earth (it's far too expensive for round-trip travel). That alone would eventually lead to speciation. Then there's the dramatic differences in the environment. Yeah, when humanity spreads among the stars, it will be humanities among the stars.

Thanks for your response but that's not the point I was getting at. My comment was intended to illicite a response from King.

 

populations evolve not individuals...

Correct. But my question was aimed at King as his posts appear to indicate that he thinks individuals evolve, not polpulations. I wanted to clarify this before continuing. Thanks for the reply.

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The bigger the population the larger the source of new mutations,and the human population is bigger than ever. At present the death rate is quite low providing limited selection t=but until recent Malthusian peasant agriculture provided plenty of death and selection for a new environment. The current low mortality just means that selection has shifted to fertility. The traits that lead to the most babies shall inherit the Earth. But the status quo is unstable it either leads to robots taking over or collapse and a new dark age, I have not decided which.

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  • 4 weeks later...

I made this point in the speculations section and was told by Moontanman and Ophiolite that I'm wrong. Now the last Biology class I took was Gr 10 in !974 so I'm not even an amateur, but I would certainly like to know why I'm wrong.

 

It seems to me that even though the rate of mutations remains constant for an advanced civilization, the process of natural selection ( by the environment ) is no longer valid as the advanced civilization can modify/alter its environment such that no trait has an advantage and is ( naturally ) selected.

 

This is a very simplistic example but bear with me. Consider two monkeys, one with good eyesight and one extremely myopic, living in the trees. As they jump from branch to branch the myopic monkey misjudges distances, and falls to its death. It will never pass on its elongated eyeball, myopic gene while the monkey with good eyesight will.

Now assume these two monkeys develop an advanced, intelligent civilization and learn to grind glass lenses. The myopic monkey is now able to wear glasses ( or even contacts ) and will not have a disadvantage for natural selction and survives its environment, hopefully to reproduce and pass on its elongated eyeball, myopic gene.

 

Intelligence or more accurately the ability to alter the environment which does the selecting, effectively put an end to natural selection, which is the basis for passing on selected genes and evolution as we know it.

Edited by MigL
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I made this point in the speculations section and was told by Moontanman and Ophiolite that I'm wrong. Now the last Biology class I took was Gr 10 in !974 so I'm not even an amateur, but I would certainly like to know why I'm wrong.

 

It seems to me that even though the rate of mutations remains constant for an advanced civilization, the process of natural selection ( by the environment ) is no longer valid as the advanced civilization can modify/alter its environment such that no trait has an advantage and is ( naturally ) selected.

Evolution may be defined as the change in allele frequency in a population. By changing the environment in such a way that individuals with previously disadvatageous genes may survive and procreate is, ipso facto, generating evolution of the species. For the more 'conventional', layperson's view of evolution, I take it you have not viewed any of the heart rending images put out by charities to raise money for relief in parts of Africa, or considered the selection mechanisms at work in the favelas of Rio. Be assured, the species is evolving.

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