Thread: Arg the natural selection battle

So I'm trying to argue and trying to back up my statements that more poor countries will see evidence of natural selection taking place as the residents need to reproduce a significant amount of offspring to survive as opposed to those who live in more wealthy arenas where they can receive the benefits that can help keep their offspring alive longer. Perhaps I have a misconception of natural selection, I don't know, but any and all help on this matter would benefit me, even if I am wrong. Articles would help too .

one item i've heard of natural selection in action is HIV in africa : it seems that chimpanzees have about 9 mechanisms to prevent the virus from "docking" prior to infecting a cell, and hence are immune

humans on the other hand have only 1 or 2

the HIV tragedy in africa has at least one silver lining : it seems that the defence mechanism in africans now varies between 3 and 5, so it would appear that given another century, they could be immune as well

Originally Posted by Deroument

So I'm trying to argue and trying to back up my statements that more poor countries will see evidence of natural selection taking place as the residents need to reproduce a significant amount of offspring to survive as opposed to those who live in more wealthy arenas where they can receive the benefits that can help keep their offspring alive longer. Perhaps I have a misconception of natural selection, I don't know, but any and all help on this matter would benefit me, even if I am wrong. .

I would like to point out that in the developed countries the population growth is slowing down. Reducing the number of offspring generally accelerates evolution (or so I hear). Further while in the developing countries the selection pressure may be for more offspring and children that can resist the hardships of their environment better, in the developed countries it's simply to overcome whatever it is that stops people from raising children these days. I'd say that the pressure is quite high there.

Originally Posted by Deroument

So I'm trying to argue and trying to back up my statements that more poor countries will see evidence of natural selection taking place as the residents need to reproduce a significant amount of offspring to survive as opposed to those who live in more wealthy arenas where they can receive the benefits that can help keep their offspring alive longer. Perhaps I have a misconception of natural selection, I don't know, but any and all help on this matter would benefit me, even if I am wrong. Articles would help too .

I would agree that people in poorer countries are probably more subject to natural selection - but not because they are reproducing more. It's because they lack of lot of the technological and cultural advances that protect them from natural selection - less vaccines for diseases, not as many hospitals, less infrastructure for the prediction of and reaction to natural disasters, more food and better hygiene practicies for better immune systems, etc. (Do you even know that this is fact, that the reproduction rate is higher in most poorer countries? And even if it is, it's probably due to a lot of factors other than "I need to have lot of kids cuz must of them are gonna die." Lack of sex ed and birth control, more kids means more help around the farm, more kids is a sign of status and prosperity in the culture, etc.)

Originally Posted by n300

Reducing the number of offspring generally accelerates evolution (or so I hear)

It's not really changing the number of offspring so much as decreasing generation time that accelerates evolution. Bacteria and viruses evolve very quickly becuase they can spawn a new generation in a matter of hours. That means natural selection sweeps happen every single time, wheareas in longer lived species, selection sweeps only happen every twenty years, or longer, depending on the reproductive cycle. However, generation time probably is a little shorter in poorer countries on average, because not having sex ed and good birth control and different cultural practices all can lead to girls having children at a much younger age than they usually do in wealtheir countries.

Originally Posted by "paralith

Originally Posted by n300

Reducing the number of offspring generally accelerates evolution (or so I hear)

It's not really changing the number of offspring so much as decreasing generation time that accelerates evolution. Bacteria and viruses evolve very quickly becuase they can spawn a new generation in a matter of hours. That means natural selection sweeps happen every single time, wheareas in longer lived species, selection sweeps only happen every twenty years, or longer, depending on the reproductive cycle. However, generation time probably is a little shorter in poorer countries on average, because not having sex ed and good birth control and different cultural practices all can lead to girls having children at a much younger age than they usually do in wealtheir countries.

reducing the number of offspring speeds up evolution because there is less chance of a variance being diluted by different genes

Originally Posted by Nevyn

reducing the number of offspring speeds up evolution because there is less chance of a variance being diluted by different genes

But evolution is a change in the gene frequencies of a population - if you maintain the same variant (I assume you meant variant instead of variance?) from generation to generation, there is no change occurring. Another reason why bacteria and viruses can evolve so quickly as that the large number of gene replication events creates many chances for mutations to occurr, and the more mutations there are, the more likely it is one of them will be resistant to an antibiotic, or something along those lines. Increasing the variety of your offspring increases the chances of their having differential reproductive success, and the chances of there being a different gene frequency in the population as generations go on.

This is assuming evolution and change, of course. Sometimes it's more advantageous to maintain a certain gene frequency, because it's already optimized for the environment. But the point here is accelerated evolution, not maintenance of a given genotype.

Thanks so much for your responses all. At least I'm not the only one thinking this. I had a bout with some political nuts in a political forum and the amount of people bashing me for stating that the lesser developed nations reproduce more offspring for survival purposes rose more and more throughout the thread. In fact to the point where I showed them fertility rate statistics in 3rd world countries and reasons that were already mentioned by you guys (or gals). In any case, thank you all again for the replies .

well....I would believe that people in poorer countries reproduce more, but not that they do so for survival purposes. Like I mentioned before, there's lots of other probable causes for this. Most people don't think, "Well damn, life here is so tough, I better pop out five or six kids just to make sure a few of 'em make it." There may be an underlying genetic impulse to have more children in a stressful environment because having more children will increase the chances that some of them survive - but it's most certainly not a conscious thought process, and most likely not a major cause anyway.

Especially in places where a lot of indigenous cultures still continue, you will probably have what are called natural fertility populations. These cultures do not have any significant form of birth control, and it's traditional for women to have an arranged marriage at a young age, and for them to continue having children for as long as they are reproductive. Combine these general practices with polygamy and yes, you get a much higher reproductive rate than you would see here in the US with the "4.5 people and a dog" families.

it's more the differential survival and reproduction that drives evolution - generation times and number of offspring obviously do help to some extent, but natural selection works at its most effective when times are hard (sad but true)

Poverty or Africa has no monopoly on natural selection. Natural selection works equally well on rich people in a western nation.

Evidence suggest for instance that the human brain is still evolving rapidly.

For natural selection to work you merely need a difference in reproductive success for a trait that has a genetic origin. It could be anything. There is no need for harsh living conditions. Comfortable living conditions can equally well drive evolution by means of natural selection.

I found a great site with some useful incite.
<a href=http://www.braintype.com>braintype.com</a>

Before someone misinterprets it I feel I shoulod point out, the majority of variation in the entire human species is found withing Africa, the remainder of the world is in comparison quite genetically "uniform" (excuse the term!)

This is not due to greater natural selection there than inwealthier countries, it is due to the fact that mankind originated in Africa. The variation there has always been.

Originally Posted by paralith

well....I would believe that people in poorer countries reproduce more, but not that they do so for survival purposes.

Yes they do. However the survival they are interested in is their personal survival in their old age.
It is well recognised that where infant mortality is high parents will have larger families in order to ensure that enough of their children survive to adulthood to take care of them when they are old.
The biggest factor that reduces the number of children per family is wealth. Firslty it provides a measn to secure old age, secondly it offers a higher quality of life that is diminshed by having to support large numbers of children.

Originally Posted by Ophiolite

Originally Posted by paralith

well....I would believe that people in poorer countries reproduce more, but not that they do so for survival purposes.

Yes they do. However the survival they are interested in is their personal survival in their old age.
It is well recognised that where infant mortality is high parents will have larger families in order to ensure that enough of their children survive to adulthood to take care of them when they are old.
The biggest factor that reduces the number of children per family is wealth. Firslty it provides a measn to secure old age, secondly it offers a higher quality of life that is diminshed by having to support large numbers of children.

Ah - well that is self interest, and that I agree with completely. I thought the OP was talking about more of a general survival of the species, as though individual people are concerned about that. The terminology and wording used suggested that meaning to me. If I assumed wrongly, I apologize.

Originally Posted by paralith

Originally Posted by Ophiolite

Originally Posted by paralith

well....I would believe that people in poorer countries reproduce more, but not that they do so for survival purposes.

Yes they do. However the survival they are interested in is their personal survival in their old age.
It is well recognised that where infant mortality is high parents will have larger families in order to ensure that enough of their children survive to adulthood to take care of them when they are old.
The biggest factor that reduces the number of children per family is wealth. Firslty it provides a measn to secure old age, secondly it offers a higher quality of life that is diminshed by having to support large numbers of children.

Ah - well that is self interest, and that I agree with completely. I thought the OP was talking about more of a general survival of the species, as though individual people are concerned about that. The terminology and wording used suggested that meaning to me. If I assumed wrongly, I apologize.

I sure hope that he didn't mean 'survival of the species' since this concept is still controversial according to the consensus. And by controversial I do not mean that there is a nice even split between scientists who believe in survival of the species and those who do not, but that survival of the species doesn't fit with natural selection which is purely aimed at the individual.

But since I am interpreting on an interpretation I am probably posting drivel.

Originally Posted by spuriousmonkey

I sure hope that he didn't mean 'survival of the species' since this concept is still controversial according to the consensus. And by controversial I do not mean that there is a nice even split between scientists who believe in survival of the species and those who do not, but that survival of the species doesn't fit with natural selection which is purely aimed at the individual.

Exactly. An individual animal isn't concerned with whether or not the species as a whole survives. Their "goal" is to make sure their own genes survive and spread, and even this "goal" is not a conscious one. That applies even more to people, especially since we can choose to say "to hell with reproducing! I don't feel like it." Most animals don't choose to resist the urge to merge, shall we say.

Originally Posted by spuriousmonkey

Originally Posted by paralith

Originally Posted by Ophiolite

Originally Posted by paralith

well....I would believe that people in poorer countries reproduce more, but not that they do so for survival purposes.

Yes they do. However the survival they are interested in is their personal survival in their old age.
It is well recognised that where infant mortality is high parents will have larger families in order to ensure that enough of their children survive to adulthood to take care of them when they are old.
The biggest factor that reduces the number of children per family is wealth. Firslty it provides a measn to secure old age, secondly it offers a higher quality of life that is diminshed by having to support large numbers of children.

Ah - well that is self interest, and that I agree with completely. I thought the OP was talking about more of a general survival of the species, as though individual people are concerned about that. The terminology and wording used suggested that meaning to me. If I assumed wrongly, I apologize.

I sure hope that he didn't mean 'survival of the species' since this concept is still controversial according to the consensus. And by controversial I do not mean that there is a nice even split between scientists who believe in survival of the species and those who do not, but that survival of the species doesn't fit with natural selection which is purely aimed at the individual.

But since I am interpreting on an interpretation I am probably posting drivel.

No no no, I'm sorry if my original post was taken out of context It was meant toward individuals who have very little means of aiding in the success of their offspring. People had argued about why it wouldn't work in 1st world countries and I had to counter that we have established welfare programs that can help in the success of offspring, therefore it's not necessarily vital to reproduce more offspring to garauntee a successful lineage. Please do correct me if I'm wrong as I'm still understanding this myself.

Originally Posted by paralith

Originally Posted by spuriousmonkey

I sure hope that he didn't mean 'survival of the species' since this concept is still controversial according to the consensus. And by controversial I do not mean that there is a nice even split between scientists who believe in survival of the species and those who do not, but that survival of the species doesn't fit with natural selection which is purely aimed at the individual.

Exactly. An individual animal isn't concerned with whether or not the species as a whole survives. Their "goal" is to make sure their own genes survive and spread, and even this "goal" is not a conscious one. That applies even more to people, especially since we can choose to say "to hell with reproducing! I don't feel like it." Most animals don't choose to resist the urge to merge, shall we say.

Exactly. That was my initial argument toward those that disagreed with my sentiments.

selection pressure increases, when there is a threat for survival. and where do we find the greatest threat for survival??

to quote Sartre : l'enfer c'est les autres