Has the Modern World Put an End to Human Evolution?

[middlj]

Me and a friend were talking in the pub the other day about evolution, and how some people hold the view that, because of modern engineering and medicine, human evolution by the process of natural selection has stopped.

What do you think? Has evolution stopped? If not, how are "good" or "bad" genes selected since it is rare these days for people to die before sexual maturity.

 

[russ_watters]

Just because we use technology that doesn't make what we do unnatural.

 

[Nano-Passion]

Pretty much everyone is reproducing their genes to their offspring regardless of their genetic makeup. I just don't see evolution really happening. But what I do see is a separation of almost 2 classes of being human - one short and "ugly"; and the other tall and "attractive".

This could be the possibility as this one article stated, but who knows.

 

[Antiphon]

No it hasn't. There are societal forces that have taken over for many of the natural ones.

Today there is a penalty against economic success in the form of progressive taxation. It means that productive humans don't reproduce as much as they otherwise could. The same forces subsidize over-reproduction by humans who otherwise would not be able to support as many offspring. The result is a tipping of the population numbers in favor of less survivable genetic characteristics.

Another social de-evolutionary force is the political normalization of obviously flawed genetics motivated by the desire not to hurt people's feelings. When dwarves are not discouraged from starting families of their own, you'll get more dwarfism as the most simple example.

The natural forces of disease don't play the same selective role anymore but nature is about to compensate in a big way. The bacterial gene rendering all antibiotic technology useless has evolved and is spreading fast. Within the lifetimes of people reading these posts, the world may return to a time when simple bacterial infections are fatal in huge numbers. That will reimpose strong selection again along those vectors for immunological defense.

Genetic therapies pose as-yet unknown evolutionary hazards or benefits as they come online.

 

[middlj]

Just because we use technology that doesn't make what we do unnatural.

I know, didn't suggest it did.

 

[Ryan_m_b]

Natural selection does not equal evolution although it will always play a part. There are other major mechanisms such as genetic drift, gene flow etc.

Consider it this way, there are nearly 7 billion humans, each one passes on 10 mutations to their offspring. In one generation (assuming each adult pair has a pair of children) 140 billion mutations have been passed on but there are only 3 billion base pairs to our genome! In other words with as many people surviving as possible all the non-fatal mutations will carry. If anything mankind is evolving to become more diverse.

No it hasn't. There are societal forces that have taken over for many of the natural ones.

Today there is a penalty against economic success in the form of progressive taxation. It means that productive humans don't reproduce as much as they otherwise could. The same forces subsidize over-reproduction by humans who otherwise would not be able to support as many offspring. The result is a tipping of the population numbers in favor of less survivable genetic characteristics.

Another social de-evolutionary force is the political normalization of obviously flawed genetics motivated by the desire not to hurt people's feelings. When dwarves are not discouraged from starting families of their own, you'll get more dwarfism as the most simple example.

The natural forces of disease don't play the same selective role anymore but nature is about to compensate in a big way. The bacterial gene rendering all antibiotic technology useless has evolved and is spreading fast. Within the lifetimes of people reading these posts, the world may return to a time when simple bacterial infections are fatal in huge numbers. That will reimpose strong selection again along those vectors for immunological defense.

Genetic therapies pose as-yet unknown evolutionary hazards or benefits as they come online.

Define "flawed genetics". Dwarfs can have children and lead full lives in spite of being stunted, one environments genetic disease is another's survival trait (e.g. sickle cell trait in sub-saharan aftrica). And there is no one bacterial gene rendering all antibiotic technology useless! That doesn't even make any sense, that suggests that there is one protein that can negate all antibiotics known to man. Bacteria are evolving around antibiotics yes but that doesn't mean we will go into some dark age plague scenario.

 

[Antiphon]

I wish you could be right somehow. The gene is called NDM-1.

http://articles.timesofindia.indiatimes.com/2011-04-07/delhi/29391808_1_ndm-1-ndm1-superbug

I'll define flawed genetics if you define pornography. But I ask you to be sincere and tell us if you would be happy, indifferent or sad if you had a child who suffered from genetically induced dwarfism? It may be possible to lead a fulfilling life but there's no need to to encourage society to collaborate in the selection for it.

 

[Ryan_m_b]

ndm-1 gives resistance to many beta-lactam antibiotics. Whilst it is a problem it is not the be all and end all.

I think you misunderstood what I meant, I was trying to say that whether or not a genetic disease is a disease is dependent on the environment. Put the question another way; would I be happy having a child who suffers from dwarfism if it gained resistance to a plague endemic to my region?

 

[mishrashubham]

Me and a friend were talking in the pub the other day about evolution, and how some people hold the view that, because of modern engineering and medicine, human evolution by the process of natural selection has stopped.

What do you think? Has evolution stopped? If not, how are "good" or "bad" genes selected since it is rare these days for people to die before sexual maturity.

Yes you are right, adaptations due to natural selection in humans have greatly decreased. But that does not mean evolution has stopped. What has been fueling evolution in humans today, in my opinion, is culture.

Adaptations arise in response to change in environment. But we do not live in our natural habitat anymore. We have made our own environment in the form of culture.

An example that I read somewhere, talks about modern lifestyle in cities. It says that human males may be quickly evolving to increase their sperm efficiency. Sperms are increasing their motility in order to win the race to reach the egg first. This might result from cities creating more sexual partners and thus increasing competition among males. I agree that this falls more under sexual selection but cultural influences can be clearly seen.

Another interesting example; Usually genes which act after reaching the age of sexual maturity are not subjected to selection. In fact one widely prevalent theory about senescence is that it results from the accumulation of harmful mutations in organisms due to them not being naturally selected against. But this is challenged in the case of the "Grandmother Effect". The children of the Hazda Tribe in Tanzania are also taken care at their homes by their grandmothers, thus receiving extra care and support. This may increase their chances of survival enough to pass on their grandmother's genes for longevity.

http://www.nytimes.com/specials/women/warchive/970916_2115.html

 

[Ryan_m_b]

Yes you are right, adaptations due to natural selection in humans have greatly decreased. But that does not mean evolution has stopped. What has been fueling evolution in humans today, in my opinion, is culture.

Adaptations arise in response to change in environment. But we do not live in our natural habitat anymore. We have made our own environment in the form of culture.

An example that I read somewhere, talks about modern lifestyle in cities. It says that human males may be quickly evolving to increase their sperm efficiency. Sperms are increasing their motility in order to win the race to reach the egg first. This might result from cities creating more sexual partners and thus increasing competition among males. I agree that this falls more under sexual selection but cultural influences can be clearly seen.

Another interesting example; Usually genes which act after reaching the age of sexual maturity are not subjected to selection. In fact one widely prevalent theory about senescence is that it results from the accumulation of harmful mutations in organisms due to them not being naturally selected against. But this is challenged in the case of the "Grandmother Effect". The children of the Hazda Tribe in Tanzania are also taken care at their homes by their grandmothers, thus receiving extra care and support. This may increase their chances of survival enough to pass on their grandmother's genes for longevity.

http://www.nytimes.com/specials/women/warchive/970916_2115.html

Some years ago I read an interesting article that had taken a group of drosophila and after a certain amount of time separated the oldest from the rest and allowed them to breed. Over generations and generations the flies lived 2-3 times longer. With the increasing average age of parents in developed countries perhaps we will see a trend towards longevity over the centuries

 

[mishrashubham]

It may be possible to lead a fulfilling life but there's no need to to encourage society to collaborate in the selection for it.

ndm-1 gives resistance to many beta-lactam antibiotics. Whilst it is a problem it is not the be all and end all.

I think you misunderstood what I meant, I was trying to say that whether or not a genetic disease is a disease is dependent on the environment. Put the question another way; would I be happy having a child who suffers from dwarfism if it gained resistance to a plague endemic to my region?

I agree with Ryan. But while dwarfism is merely a social problem which can be dealt with, more serious and possibly life threatening genetic diseases like Haemophilia and similar recessive diseases should be prevented from spreading. I think that if a person has such a disease or is very likely to be a carrier due to past history of disease occurrence in family should be discouraged from reproducing and passing on the trait.

I understand the ethical issues regarding "the freedom to reproduce", but why should one give the same suffering to one's children when they know they might be responsible for it?

 

[mishrashubham]

Consider it this way, there are nearly 7 billion humans, each one passes on 10 mutations to their offspring. In one generation (assuming each adult pair has a pair of children) 140 billion mutations have been passed on but there are only 3 billion base pairs to our genome! In other words with as many people surviving as possible all the non-fatal mutations will carry. If anything mankind is evolving to become more diverse.

Ah yes, important point. A large population size increases the rate of mutation (due to increased probability of mutations) in the population an thus increases rate of evolution.

http://www.ncbi.nlm.nih.gov/pubmed/17348929

 

[Ryan_m_b]

Perhaps discouraged from reproducing is the wrong approach, I for one would absolutely loath the idea of the government being entrusted with the responsibility of deciding who should and should not have kids.

Alternatively genetic testing for prospective parents, developing much better IVF screening methods and increased education could help people make an informed decision to prevent their child from inheriting a disease

 

[Antiphon]

I agree with you and Ryan; diversity is very important for all the reasons cited.

The flip side of eradicating genetic diseases is precisely this reduction of unknown potential survival advantages. That's why I left the genetic therapy issue an open question. We could do tremendous damage to ourselves down the road by eradicating a raft of diseases at the genetic level. I'm all for it (progress) but an advanced approach would preserve the "flawed" genes for future study the way smallpox has been preserved.

 

[Ryan_m_b]

I agree with you and Ryan; diversity is very important for all the reasons cited.

The flip side of eradicating genetic diseases is precisely this reduction of unknown potential survival advantages. That's why I left the genetic therapy issue an open question. We could do tremendous damage to ourselves down the road by eradicating a raft of diseases at the genetic level. I'm all for it (progress) but an advanced approach would preserve the "flawed" genes for future study the way smallpox has been preserved.

I agree. Molecular genetics and proteomics are only a few decades old, I always get the feeling that the last few decades of discovery in biology have just revealed how much we have left to know. Perhaps one day our understanding of genetics, proteomics and phenomics will mean that when a disease occurs we can easily design a gene therapy to deal with it.

 

[mishrashubham]

Perhaps discouraged from reproducing is the wrong approach, I for one would absolutely loath the idea of the government being entrusted with the responsibility of deciding who should and should not have kids.

Alternatively genetic testing for prospective parents, developing much better IVF screening methods and increased education could help people make an informed decision to prevent their child from inheriting a disease

I know, but "discouraging" still leaves the person with an option. Now I did not imply government supervision but still as you rightly said increasing education would definitely help in this situation.

I personally dream of a time when genetic tests can be easily done to check for such diseases and thus effectively control them.

 

[Ryan_m_b]

I know, but "discouraging" still leaves the person with an option. Now I did not imply government supervision but still as you rightly said increasing education would definitely help in this situation.

I personally dream of a time when genetic tests can be easily done to check for such diseases and thus effectively control them.

I think encouragement to seek treatment would be another. I share your dream. Personalised medicine to deal with conditions like this would be great

 

[SW VandeCarr]

Me and a friend were talking in the pub the other day about evolution, and how some people hold the view that, because of modern engineering and medicine, human evolution by the process of natural selection has stopped.

What do you think? Has evolution stopped? If not, how are "good" or "bad" genes selected since it is rare these days for people to die before sexual maturity.

You bring up a very interesting subject which I find very compelling. Humans have not for some time lived under the rigorous "survival of the fittest" regime that animals in the wild endure. There are many factors involved: high levels of access to food, clothing and shelter; medical interventions of all kinds, ect. Selective "breeding" may or not be a factor as animals in the wild appear to do this with female selection being the rule. I think this also is true in humans, but not necessarily always for the same factors.

Has evolution stopped? I think it has not stopped and could vastly accelerate. The mechanism will be intelligent design (ID). These are dirty words for biologists, but that's in the context of past evolution. It may well be a major factor in future evolution for obvious reasons. Humans are on the threshold something very major in the evolution of life on earth: life designed by life according to the conscious specification of living things, probably combined with natural selection under controlled conditions. This all has the flavor of science fiction, but it is all clearly possible. You really can't give a sound argument why this is not possible or even likely. Of course, it's not certain. It's also a real possibility that humans could become extinct or at least regress to a small low tech society after some catastrophe or catastophes, human made or natural or both. If this happens, then evolution according to nature's rules will resume full force.

 

[capslockf9]

As the ozone diminishes ulta-violet rays will cause more damage to or kill more white skinned humans. Ultra violet rays will kill plants. Humans will be undernourished and grow smaller. And then humans will be dark midgets.

 

[mishrashubham]

As the ozone diminishes ulta-violet rays will cause more damage to or kill more white skinned humans. Ultra violet rays will kill plants. Humans will be undernourished and grow smaller. And then humans will be dark midgets.

Wow, Awesome theory...

 

[DavidMcC]

Just because we use technology that doesn't make what we do unnatural.

That's a matter of the definition of "unnatural". If it simply means "depends on deliberate human actions that no other species could do", then it can also be considered to be a "natural" result of evolution, but one that would not happen if humans did not exist.

 

[Morse]

Society allows citizens with severe or mild genetic deficiencies be successful, but the opposite sex might not necessarily allow them to be successful. Just saying.

So there's sexual selection, as a female is far more likely to reproduce with somebody that is fit and healthy than somebody with a crippling disability. Also like somebody else mentioned, drift and flow, as well as genetic insertions directly into our DNA.

 

[BoomBoom]

Today there is a penalty against economic success in the form of progressive taxation. It means that productive humans don't reproduce as much as they otherwise could. The same forces subsidize over-reproduction by humans who otherwise would not be able to support as many offspring. The result is a tipping of the population numbers in favor of less survivable genetic characteristics.

I find it quite humorous that you would equate a persons income level to that of their genetic fitness.

 

[russ_watters]

I find it quite humorous that you would equate a persons income level to that of their genetic fitness.

Why?

 

[lisab]

Why?

Maybe because genes have no such preference. I hear the same sentiment from people who think Darwin was wrong, because "look at all the poor uneducated people having so many kids!" "Survival of the fittest" isn't quite right. The fittest (or richest, or smartest, etc) aren't selected; the "breeders" are.

 

[mishrashubham]

I find it quite humorous that you would equate a persons income level to that of their genetic fitness.

I don't think he is equating income to reproductive success.
What he is simply trying to say is that what would otherwise be considered unfit in a natural environment is not so in our man-made society.
So the the meaning of 'fitness' now changes with the change in external conditions.

 

[Ryan_m_b]

I don't think he is equating income to reproductive success.
What he is simply trying to say is that what would otherwise be considered unfit in a natural environment is not so in our man-made society.
So the the meaning of 'fitness' now changes with the change in external conditions.

I agree but regardless of our society "fitness" is a measure of the proliferative(ness) of an individual. Whilst we may not undergo the same selection pressures the things that we culturally value do not necessarily lead to passing on our genes more than others. Additionally the things that make us valued culturally can have nothing to do with our genetics

 

[mishrashubham]

I agree but regardless of our society "fitness" is a measure of the proliferative(ness) of an individual.

Exactly. That is the point. If you have something that gives your children a better chance of surviving and passing on their own genes, you are fitter.

Whilst we may not undergo the same selection pressures the things that we culturally value do not necessarily lead to passing on our genes more than others.

They do. There are some tribes in Africa which consider women with lip plates beautiful.
http://en.wikipedia.org/wiki/Lip_plate

And the bigger the lip plate, the better are the chances of a girl getting a groom. If suppose there is a gene which allows the lip to stretch better may be by increasing its elasticity or similar, a girl having it will be reproductively more successful.

P.S- I DO NOT claim that such a gene exists.

 

[Ryan_m_b]

They do. There are some tribes in Africa which consider women with lip plates beautiful.
http://en.wikipedia.org/wiki/Lip_plate

And the bigger the lip plate, the better are the chances of a girl getting a groom. If suppose there is a gene which allows the lip to stretch better may be reducing its elasticity or similar, a girl having it will be reproductively more successful.

P.S- I DO NOT claim that such a gene exists.

Yeah that's fair enough but much of what we value in a person as a society isn't necessarily (and I would say isn't often) rewarded with more offspring. You can be beautiful, popular, funny, rich, drive an Aston martin and play striker for Real Madrid but that's more likely to get you far more sexual partners than it will kids!

 

[mishrashubham]

Yeah that's fair enough but much of what we value in a person as a society isn't necessarily (and I would say isn't often) rewarded with more offspring. You can be beautiful, popular, funny, rich, drive an Aston martin and play striker for Real Madrid but that's more likely to get you far more sexual partners than it will kids!

Effective contraceptive methods are a recent phenomenon. Society has existed for millennia.
Plus I would consider any apparently social behaviour that gets more sexual partners, a byproduct of sexual selection.