Evolution of humans

[Stranger]

I agree to so e extent, but to be beneficial they have to be more efficient at passing on the gene. This would mean that others would not be as successful at passing on their genes.
We strive quite rightly to make sure people are not disadvantaged so I am not sure how this evolution is taking place. Unless there are losers there is nothing for evolution to grab onto. Is there?
Or am I missing it?

To the extent that people have access to modern health care, where we (rightly) endeavour to enable people survive and reproduce regardless of genetic problems (and also enable the healthy to limit their reproduction via contraception), you're correct and the potential for natural selection is limited.

However, even modern health care cannot cure all problems, is far from universally available even today, and has only been available for a tiny fraction of human history.

The future (natural) evolution of humans depends critically on whether technological society survives, continues to make progress in medicine, and to what extent it is made available to the entire world population.

[SusanDoris]

I agree to so e extent, but to be beneficial they have to be more efficient at passing on the gene.

But they cannot take any positive, active steps to become more efficient. That happens or it doesn't.

This would mean that others would not be as successful at passing on their genes.

That's their bad luck , and why such huge percentages of species of life have become extinct. Nowadays medical help and care can help individuals cope with problems, but that's not evolution.

We strive quite rightly to make sure people are not disadvantaged so I am not sure how this evolution is taking place. Unless there are losers there is nothing for evolution to grab onto. Is there?

Again, evolution is not active,, does not grab onto something; mutations are either fortunate for the species or not.

Just to think of the several billion years when the planet was forming life starting and, from then on, continuing in an unbroken line of life via the dinosaurs, smaller mammals, Ice Ages and then an ape species having mutations which were passed on and here we are, homo sapienssapiens ... ... well, it is far more amazing than any sci-fi story ever invented!
Or am I missing it?
[/quote]

[BeRational]

But they cannot take any positive, active steps to become more efficient. That happens or it doesn't.That's their bad luck , and why such huge percentages of species of life have become extinct. Nowadays medical help and care can help individuals cope with problems, but that's not evolution.Again, evolution is not active,, does not grab onto something; mutations are either fortunate for the species or not.

Just to think of the several billion years when the planet was forming life starting and, from then on, continuing in an unbroken line of life via the dinosaurs, smaller mammals, Ice Ages and then an ape species having mutations which were passed on and here we are, homo sapienssapiens ... ... well, it is far more amazing than any sci-fi story ever invented!
Or am I missing it?

I think I understand all that but if the unlucky ones still have children then evolution has no effect surely.
I cannot yet see how being lactose intolerant disadvantages individuals in respect of them having children. If that's the case how does evolution pass on this trait, when the trait of not have the gene replicates equally well?

[Harrowby Hall]

I think I understand all that but if the unlucky ones still have children then evolution has no effect surely.

The change doesn't happen instantly but over generations. The children of those who do not have the mutation - and their children - will find it harder to survive than the children of those who do. Don't forget, until relatively recently many children did not survive until adulthood. Medical intervention, as we understand it, is rather less than two hundred years old.

I cannot yet see how being lactose intolerant disadvantages individuals in respect of them having children. If that's the case how does evolution pass on this trait, when the trait of not have the gene replicates equally well?

My understanding (which may be incorrect) is that all babies are born able to digest lactose but that this ability fades away as the child develops in many ethnic groups. The European ability of adults to digest lactose is about 7,000 years old. Your comment suggests that the process was the other way round: the ability to digest lactose was universal but most of humanity lost it.

I'm not sure, however, whether the inability to digest lactose and lactose intolerance are necessarily the same thing. Perhaps someone can enlighten me.

[BeRational]

The change doesn't happen instantly but over generations. The children of those who do not have the mutation - and their children - will find it harder to survive than the children of those who do. Don't forget, until relatively recently many children did not survive until adulthood. Medical intervention, as we understand it, is rather less than two hundred years old.

My understanding (which may be incorrect) is that all babies are born able to digest lactose but that this ability fades away as the child develops in many ethnic groups. The European ability of adults to digest lactose is about 7,000 years old. Your comment suggests that the process was the other way round: the ability to digest lactose was universal but most of humanity lost it.

I'm not sure, however, whether the inability to digest lactose and lactose intolerance are necessarily the same thing. Perhaps someone can enlighten me.

Again I sort of agree, but NOW all people survive intolerant or not, so evolution has nothing to work with. Both sets of genes copy just as well, albeit we as a society intervene to make it happen.
In my limited understanding, if people with or without the gen survive long enough to have children, there can be no evolution in the direction of genes for tolerance.

I am not saying you are wrong, I am questioning my understanding of the mechanic of selection, when we get involved to stop selection happening.

[Udayana]

But they cannot take any positive, active steps to become more efficient. That happens or it doesn't.

That's their bad luck , and why such huge percentages of species of life have become extinct. Nowadays medical help and care can help individuals cope with problems, but that's not evolution.Again, evolution is not active,, does not grab onto something; mutations are either fortunate for the species or not.

Just to think of the several billion years when the planet was forming life starting and, from then on, continuing in an unbroken line of life via the dinosaurs, smaller mammals, Ice Ages and then an ape species having mutations which were passed on and here we are, homo sapienssapiens ... ... well, it is far more amazing than any sci-fi story ever invented!
Or am I missing it?

Well, I think that has been mostly true .. up to now.  Of-course people could affect long term human development by simply having more children than everyone else. Now we have more effective tools to change which genes to pass on or not - tools which will inevitably be used - for good or bad. In addition, we are effectively in charge of much animal life too.

It is not really a question of survival - it is a statistical effect. Lactose intolerance is common in China, or was, but social and economic factors encourage people to consume milk products and, over time, the population becomes more lactose tolerant- just because those that are tolerant tend to rise in society, have more wealth and influence and their children tend to do better.         

[Udayana]

The change doesn't happen instantly but over generations. The children of those who do not have the mutation - and their children - will find it harder to survive than the children of those who do. Don't forget, until relatively recently many children did not survive until adulthood. Medical intervention, as we understand it, is rather less than two hundred years old.

My understanding (which may be incorrect) is that all babies are born able to digest lactose but that this ability fades away as the child develops in many ethnic groups. The European ability of adults to digest lactose is about 7,000 years old. Your comment suggests that the process was the other way round: the ability to digest lactose was universal but most of humanity lost it.

I'm not sure, however, whether the inability to digest lactose and lactose intolerance are necessarily the same thing. Perhaps someone can enlighten me.

From the NHS website:

"Lactose intolerance is a common digestive problem where the body is unable to digest lactose, a type of sugar mainly found in milk and dairy products."

[Udayana]

Again I sort of agree, but NOW all people survive intolerant or not, so evolution has nothing to work with. Both sets of genes copy just as well, albeit we as a society intervene to make it happen.
In my limited understanding, if people with or without the gen survive long enough to have children, there can be no evolution in the direction of genes for tolerance.

I am not saying you are wrong, I am questioning my understanding of the mechanic of selection, when we get involved to stop selection happening.

You are right in that there will always be a proportion of the population that will be intolerant - the genes will be passed on. In every generation the parent's genes (along with ancestral genes carried) are shuffled - the phenome depends on which genes are dominant or expressed rather than the full content of the genome.

- But the size of that proportion also depends on many other factors - not only on whether children survive, but on how well they do relative to other groups.

 
 

[SusanDoris]

I think I understand all that but if the unlucky ones still have children then evolution has no effect surely.
I cannot yet see how being lactose intolerant disadvantages individuals in respect of them having children. If that's the case how does evolution pass on this trait, when the trait of not have the gene replicates equally well?

If they have children and the descendants of those children are alive  today and carry the mutation, then whatever the mutation was, it did not prevent them from surviving, it was just a mutation that did nothing in particular!! They would have been able to adapt to changes in environment with or without it. To be lactose tolerant would appear to be one of those traits.

Evolution doesn't do anything, it is just a word to describe what has happened to living things.

Edited to add: Evolution does not have direction. It happens or it doesn't. With hindsight, we can see what we can label direction, but that doesn't change the facts.
Also, whatever medical changes can do to help the living, the chances of any such change just possibly being passed on to any more than just a single child or two is as near impossible as makes no difference. Just think of the billions of us there are!

[BeRational]

If they have children and the descendants of those children are alive  today and carry the mutation, then whatever the mutation was, it did not prevent them from surviving, it was just a mutation that did nothing in particular!! They would have been able to adapt to changes in environment with or without it. To be lactose tolerant would appear to be one of those traits.

Evolution doesn't do anything, it is just a word to describe what has happened to living things.

Edited to add: Evolution does not have direction. It happens or it doesn't. With hindsight, we can see what we can label direction, but that doesn't change the facts.
Also, whatever medical changes can do to help the living, the chances of any such change just possibly being passed on to any more than just a single child or two is as near impossible as makes no difference. Just think of the billions of us there are!

I think you are missing my point. I agree that in the wild being lactose tolerant would be a useful evolutionary advantage. In the current climate though it does not give any advantage, so humans do not tend to evolve to be lactose tolerant for the simple reason that non lactose tolerant people also survive to have offspring. That as far as I understand it, is evolution.
Because of the way our civilisation currently is, we have effectively turned evolution off. Sure there will be mutations, but those mutations are mitigated by our efforts.

[SusanDoris]

I think you are missing my point. I agree that in the wild being lactose tolerant would be a useful evolutionary advantage. In the current climate though it does not give any advantage, so humans do not tend to evolve to be lactose tolerant for the simple reason that non lactose tolerant people also survive to have offspring. That as far as I understand it, is evolution.

It is simply an aspect of the unbroken line of life – that some mutations happen and don’t make a lot of difference. However, if they eventually cease to show, that would be caused by another random mutation.

Because of the way our civilisation currently is, we have effectively turned evolution off

absolutely disagree. Nothing can turn evolution off. The DNA is constantly split and rejoined as new cells are constantly being made and it is unbelievably fantastically marvellous that this system has continued for so long and still continues. No-one can take any action which will alter that procedure.

. Sure there will be mutations, but those mutations are mitigated by our efforts.

Yes, I agree, but only for each individual as they are able to take advantage of those efforts. Random mutations can happen anywhere in the trillions of cell replications that occur in the billions of people alive today.  Our efforts cannot change that.

and it causes extinction, it iis no-one' fault and

[SteveH]

I think you are missing my point. I agree that in the wild being lactose tolerant would be a useful evolutionary advantage. In the current climate though it does not give any advantage, so humans do not tend to evolve to be lactose tolerant for the simple reason that non lactose tolerant people also survive to have offspring. That as far as I understand it, is evolution.
Because of the way our civilisation currently is, we have effectively turned evolution off. Sure there will be mutations, but those mutations are mitigated by our efforts.

I don't think lactose tolerance confers no advantage. A lactose-intolerant person might take lactose by mistake (or wilfully, out of curiosity, in the case of a small child), and snuff it as a result.

[jeremyp]

I agree that in the wild being lactose tolerant would be a useful evolutionary advantage.

That depends on what you mean by "in the wild". Obviously, for mammals, being lactose tolerant until weened is a must, but after that, producing the necessary enzymes to digest milk is a waste of time and developing lactose intolerance would be an evolutionary advantage.

In the current climate though it does not give any advantage, so humans do not tend to evolve to be lactose tolerant for the simple reason that non lactose tolerant people also survive to have offspring.

Certainly that is true if you are talking about modern civilisation, but if you lived in a prehistoric society that relied heavily on dairy farming, it would be life or death.

Because of the way our civilisation currently is, we have effectively turned evolution off. Sure there will be mutations, but those mutations are mitigated by our efforts.

I don't think that is the case. There will still be evolution, but we can't say in which direction it will go. For example, if there is a negative correlation between intelligence and family size (Not saying there is, I just made that up), maybe there would be evolutionary pressure towards humans getting more stupid.

[Spud]

Maybe lactose tolerance can be turned on or off, depending on whether it's needed? No idea if that's the case but might make sense.

[SusanDoris]

Maybe lactose tolerance can be turned on or off, depending on whether it's needed? No idea if that's the case but might make sense.

No, I'm afraid it doesn't! Mutations either happen or they don't. They cannot be initiated by a species.  Remember that:

In the King James Version of the Bible the text reads: Which of you by taking thought can add one cubit unto his stature?

so I have to concede that the biblical quote makes sense!

[Harrowby Hall]

In the early years of this century, I visited Japan on four occasions. Among the things which I observed were differences between old and young people which were probably the consequence of different dietary practices.

Young Japanese people were taller than older. I guessed that this was possibly due to the arrival of McDonalds and the increased amount of protein that this had made available. But even more noticeable - and one which saddened me - was a significant number of elderly women bent almost double by apparent osteoporosis. This is something which we, in Europe, where we have adequate calcium supplies in the form of milk, see rarely. My expectation is that the ready availability of milk in Japanese supermarkets will ensure that this condition will become rare.

I do not know whether this milk has reduced levels of lactose. My assumption has been that in people who are not of European heritage that lactose passes through the gastro-intestinal tract without being digested. This suggests to me that they would be lactose tolerant. Were they lactose intolerant then they would suffer from some observable pathological reaction. Certainly there would have been insufficient time for mutation to have occurred.

[Udayana]

...
I do not know whether this milk has reduced levels of lactose. My assumption has been that in people who are not of European heritage that lactose passes through the gastro-intestinal tract without being digested. This suggests to me that they would be lactose tolerant. Were they lactose intolerant then they would suffer from some observable pathological reaction. Certainly there would have been insufficient time for mutation to have occurred.

Well ... it doesn't really work like that.

In populations where milk has not been part of the traditional diet, such that most people do not generate lactase after weaning (lactase helps digest the lactose in milk), consumption of milk products causes lactose to accumulate in the lower intestinal tract or bowel where it supports colonies of bacteria that cause the various symptoms of lactose intolerance.

So if the Japanese do not have the genetics to continue lactase production and start consuming milk (actually some forms of milk - eg some yogurts can mitigate the bad effects) they will suffer from lactose intolerance. 

And why is it only the women suffering from osteoporosis? Could be that bearing children is heavily demanding of calcium from the mother? The fact is that calcium is available in plentiful supply in a variety of fruit and vegetables.

We all need to understand our genetics and thus the likely behaviour of our digestion system and biology - and optimise our nutrient intake to suit.

   

[SusanDoris]

In the early years of this century, I visited Japan on four occasions. Among the things which I observed were differences between old and young people which were probably the consequence of different dietary practices.

Young Japanese people were taller than older. I guessed that this was possibly due to the arrival of McDonalds and the increased amount of protein that this had made available. But even more noticeable - and one which saddened me - was a significant number of elderly women bent almost double by apparent osteoporosis. This is something which we, in Europe, where we have adequate calcium supplies in the form of milk, see rarely. My expectation is that the ready availability of milk in Japanese supermarkets will ensure that this condition will become rare.

I do not know whether this milk has reduced levels of lactose. My assumption has been that in people who are not of European heritage that lactose passes through the gastro-intestinal tract without being digested. This suggests to me that they would be lactose tolerant. Were they lactose intolerant then they would suffer from some observable pathological reaction. Certainly there would have been insufficient time for mutation to have occurred.

I am running a topic on 'our evolution' on the Science board of the GH forum, a forum  where mis information about evolutionary biology is quite widespread unfortunately. Two of the posters started talking about an Anne McCaffrey and a Juan Enriquez, in relation to their alt views on evolution, so I looked them up. The former is a famous ci-fi writer but I have not looked up what she had to say about evolutionary biology. The second a well-known businessman who seems to be 'in' with the DNA discoveries people. I saw a link to a video so clicked on it. The intro mentioned a TED talk connection, but the first part of the video was quite enough for me. Juan Enriquez was giving a talk with a screen and, in rather supercilious tones, was talking about Darwin's finches as if Darwin was quite wrong about all that. So I checked out that too! And of course Darwin, when he first saw and collected some of those birds to bring back to England did not at that time consider why or how the birds not only had different beaks, but had become 18 different species.

The changes in the physical size and shape of Japanese people since the much closer links with the western world have been noticed for some time, havn't they. What I find one of the most interesting things about the human species is that, even though there are so many different sizes and shapes, all humans can still interbreed which, I suppose, proves how much communication there must have been since modern humans evolved. As a matter of irrelevant fact, both my nephews married Japanese girls and both have families.   

The current chapter I am reading is about the 11,000 years ago start of agriculture.

[SusanDoris]

Well ... it doesn't really work like that.

In populations where milk has not been part of the traditional diet, such that most people do not generate lactase after weaning (lactase helps digest the lactose in milk), consumption of milk products causes lactose to accumulate in the lower intestinal tract or bowel where it supports colonies of bacteria that cause the various symptoms of lactose intolerance.

So if the Japanese do not have the genetics to continue lactase production and start consuming milk (actually some forms of milk - eg some yogurts can mitigate the bad effects) they will suffer from lactose intolerance. 

And why is it only the women suffering from osteoporosis? Could be that bearing children is heavily demanding of calcium from the mother? The fact is that calcium is available in plentiful supply in a variety of fruit and vegetables.

We all need to understand our genetics and thus the likely behaviour of our digestion system and biology - and optimise our nutrient intake to suit.

 

We are all lucky that there is so much information available about nutritional values of food, and my contemporaries and I, wartime children, sometimes talk about our diets then and wonder why that has meant we are not all dead yet!!
With my familly history of heart attacks and strokes, I have, for a greater part of my life tried to follow a sensible middle way and I hope that, along with the heart surgery and pills of todays medical care, plus sensible exercising, will continue to keep me going for a year or two more!

[Spud]

For the record, answersingenesis says that lactose intolerance is 'normal' and that the mutations for lactase persistence are not an increase in genetic information but a decrease, and so are not 'evolution'.

[Nearly Sane]

For the record, answersingenesis says that lactose intolerance is 'normal' and that the mutations for lactase persistence are not an increase in genetic information but a decrease, and so are not 'evolution'.

For the record answersingenesis is dishonest ignorant bollocks

[jeremyp]

For the record answersingenesis is dishonest ignorant bollocks

A stopped clock and all that.

[Nearly Sane]

A stopped clock and all that.

Except evolution is not 'increase in genetic information' so not even that.

[Spud]

Except evolution is not 'increase in genetic information' so not even that.

So it's decrease in genetic information?

[Nearly Sane]

So it's decrease in genetic information?

Woo, and we have a winner in a false dichotomy contest.  Misrepresenting evolution as answersingeneneis do doesn't mean the opposite is what it is.  So if I say  cheese is high tannins, and you say it isn't, it doesn't you are saying cheese is low tannins. It's irrelevant.