On Tendencies to Believe that Evolution Creates Stronger Beings

[The Madman]

Our species has done a lot in the relatively short time it’s spent here on earth. We’ve mastered fire, discovered cures for deadly diseases, put men on the moon, explored the depths of our planets oceans, and unleashed the energy of the atom. Throughout the process, however, we’ve pushed countless species into extinction, polluted the air and water, exhausted many of earth’s natural resources, and offset its climate. But, for a moment, let’s put the negative consequences felt by our environment due to the rise of man aside. After all, this essay isn’t about those consequences; it’s about the ones a little closer to home.

 

We tend to think of the human a race as getting stronger and stronger all the time. As a whole, we no doubt are. Within the next few decades we may put humans on another planet and discover a cure for the common cold. Thanks to modern society and its benefits, the human race will continue to strengthen and expand. But how will the individual human fare? Medicines can cure just about anything these days and vaccines are improving all the time (naturally, they have to). The average human life expectancy, as a result, is also on the rise. Despite all these things, the individual homo sapien will, from nature’s point of view, become weaker and weaker.

 

 

Let’s work with examples and hypothetical situations for this one, since they seem to make everything more easily understood. Little Jimmy falls terribly ill when he’s 8 years old. The problem isn’t unknown in children his age, though, and a cure is available for him. Lucky break for Jimmy, he can grow bigger and stronger, and will later find a mate and have children of his own. He will live his life until some other deadly virus is caught that can’t be cured, or until old age catches up with him. What does the human race get in return? Jimmy’s weak genes are thrown into the melting pot that is human DNA, and of course, more babies. Now let us also assume that the mother of his children, Linda, has a family history of breast cancer. Though she will not contract it until long after she has had three children (all boys) with Jimmy, the gene is passed along none the less. Of course there is a possibility that these genes won’t be passed down to any of Jimmy’s and Linda’s offspring. But in this grim example, we now have three humans walking around with at least one deadly gene each.

 

In nature, no cure would have been available for Jimmy’s sickness, and he would have died young, taking his recessive gene with him to the grave. Likewise, someone in Linda’s lineage may have not reproduced before the untreatable cancer took their life. Thus, no Linda. The human race would have been stronger physically speaking, but the modern society these people were born into had a cure, and gave them life so that they may (we hope) obtain a greater appreciation of the world they lived in, and make contributions, however small, towards a better society. I am not advocating in this essay that we should leave the weak and sick to whatever nature has planned for them*. Though we would be left with a much stronger, yet smaller population, the means don’t nearly justify the end. I only felt the need to raise the awareness of those not in the know. Our society is very much a double edged sword.

 

 

*Reading a magazine like “People”, you will occasionally come across a story of how a baby is born with a deadly birth defect. These defects are either very rare, or are brought on by the mother’s inability to refrain from drugs during pregnancy. In these stories, the child makes a “miraculous recovery”, usually with a lot of help from a team of doctors. The result is a severely deformed child, both inside and out. In cases like these, I fell no qualms about not letting the child live. It would not benefit society in any way. In fact, it would only take away. It would not reproduce. It would not be able to appreciate life.

Edited June 16, 2008 by swansont
turned volume down

[omnimutant]

This is already being discussed here:

http://www.scienceforums.net/forum/showthread.php?t=33545

 

I do generally accept what your saying however I like to take it a bit further. Where medicine cures the problems to an extent, it is not perfect. That alone is enough not to worry about a long term weakening on the human race. I do believe that technology has basically got to the point that mutation in humans almost does not mater anymore, but evolution still happens.

 

Lets say that using your example, the "bad" mutation becomes the norm because of technology. Well in that case we still have technology so there is nothing to worry about. But in an extinction situation, where say all our technological advances and the knowledge of such mysteriously vanishes. We still will evolve to fit our enviornment. The "bad" mutations will eventually breed out as new mutations occur that are better suited to handle our new enviornment. Lets not forget that we have already evolved(?) the ability to create technology, and that will aid in the prolonging of an immediate wipe out of our species, while any new evolutionary changes take place. The cool thing about our ability to create technology is that we seem to be even better at it in dire situations.

[The Madman]

thanks for the feed-back omnimutant. i guess there's no way to prove it, but my ideas were independently formed. it's a self consuming circle then, isn't it... we need to develop the "technology" to keep us alive, but we do this because the previous technology kept the weaker genes in the mix, allowing them to spread. this promts us to contine developing the tech. and so it goes...

[omnimutant]

It keeps us busy

[jimmydasaint]

Rather than starting another thread, can I please add to this interesting discussion, albeit with a slight digression. If a favourable mutation arose to allow high levels of cholesterol in a family without associated cardiac disease, but the family were in an isolated location (e.g. Milan, Italy), how would the gene be spread further than this location? Or does it just spread in that particular small location and stay there?

[The Madman]

i guess if it has arisen(?) in one locale, we can assume it will arise elsewhere, hopefully in a location with a high human population.

[Edtharan]

The result is a severely deformed child, both inside and out.

Most will be, but remember there will be some that the world is better with (and you can only tell after the fact). People like Steven Hawking.

 

Despite all these things, the individual homo sapien will, from nature’s point of view, become weaker and weaker.

Actually, No.

 

Variation within a population is a good measure of that species "strength". Species that are limited in their genetic diversity tend to be quite "weak". Reduction in genetic diversity within a species leads to inbreeding and this brings out many recessive genetic problems.

 

With a large variation in genes within a population, this "future proofs" the species against changes in the environment. A new disease might arise and a varied population is more likely to have individuals that are immune (or have a reduced effect from it), or if the climate changes, some individuals will be better adapted in the more varied populations.

 

We are facing this problem at the moment with some crop species. Most Banana plants are virtually identical genetically. This means that certain diseases that they can get will have an equal effect through out the population. So when disease does strike (as it has in many places), whole plantations can get wiped out.

[foodchain]

 

Evolution is rather simple. variation, reproduction, selection. Its understanding this that helps. A common sense example of this would be that aquatic environments differ from terrestrial ones, or how birds can fly. So in evolution you can say that multicellular life was selected for, and is selected for. I mean life may not be able to evolve in on a planet like Jupiter, this does not mean life cant ever interact with it right, so selection is temporal. I mean how could 99% of life in its form that was at one point or not selected for become selected against and subsequently go extinct?

 

So I guess my answer is while humans may be a pinnacle of evolution now, its still just the same reality that is at play, such as say selection in the form of global warming and whatever impact that brings.

 

So this is why biodiversity in general is good for life, if a comet of some size struck the earth maybe only a minor percent of life in some form would be able to live on, vs. humans as a specie which I wager would go extinct.

[lucaspa]

In nature, no cure would have been available for Jimmy’s sickness, and he would have died young, taking his recessive gene with him to the grave.

 

But the medical help is "nature"! It's the present environment. Also, you forget that, while you might be preserving Jimmy's "sickness", you are also preserving other, beneficial traits.

 

My favorite example is Stephen Hawking. Born with the genetic defect of Lou Gehrig's disease. Thanks to modern medicine, Hawking survived and had kids. So, the alleles for Lou Gehrig's disease were preserved, but also the alleles for Hawking's phenomenol intelligence were also preserved. Which is more beneficial in the long-term?

 

Basically, your essay makes 2 basic errors about evolution:

1. That some traits are always "good" and others always "bad". In reality, traits are "good" or "bad" depending on the environment. Medical science is part of the environment.

2. You think you are smarter than natural selection. You're not. You want to pick the traits that should be preserved and the ones that should be discarded. But you can't see into the future. In eliminating Linda because you let her mother die of cancer when medical science could cure her, you might also be eliminating an allele that provides immunity to Ebola! You just don't know.

 

Don't second guess natural selection with phrases like " The human race would have been stronger physically speaking" or we would be left with a much stronger, yet smaller population"

 

You don't know the population would be "stronger" in the face of a future environment. No one does. You are only judging "stronger" on past environments. Environments that lack our technology. If we ever lose our technology, then natural selection will select for that environment. However, if you artificially select for that, you eliminate the variation that will be needed to cope with a future environment that is not like the past.

[nstansbury]

Which would seem to make a strong case for not needlessly genetically modifying our children, on the grounds that we would be artificially selecting our future variations?

 

The corollary of this, and the answer to the originating question then is: No, by artificially prolonging life we increase the genetic diversity in the population as a whole.

 

Interesting, I like!

Edited June 18, 2008 by nstansbury

[foodchain]

Which would seem to make a strong case for not needlessly genetically modifying our children, on the grounds that we would be artificially selecting our future variations?

 

The corollary of this, and the answer to the originating question then is: No, by artificially prolonging life we increase the genetic diversity in the population as a whole.

 

Interesting, I like!

 

I think you would have to change everything else also, not just the people.

[nstansbury]

I think you would have to change everything else also, not just the people.

 

I don't follow - "everything else" what?

[Edtharan]

Which would seem to make a strong case for not needlessly genetically modifying our children, on the grounds that we would be artificially selecting our future variations?

Actually, surprisingly not.

 

If you eliminate someone because of a small amount of genetic faults (disease), then you are eliminating the rest of their genome as well. It is a case of throwing the baby out with the bathwater (as the saying goes).

 

However, if instead you genetically modify that person's genome to eliminate that disease, then you still have the rest of that person's genome (you have kept the baby but thrown the bathwater out).

[nstansbury]

However, if instead you genetically modify that person's genome to eliminate that disease

 

Ah, that's exactly why I used the word "needlessly" - I was thinking eye/hair color, size of nose etc etc - which could well contain some allele of a future variation?

 

If the genetic modification isn't assisting the genome in reproducing then genetic diversity must be reduced.

[Edtharan]

Ah, that's exactly why I used the word "needlessly" - I was thinking eye/hair color, size of nose etc etc - which could well contain some allele of a future variation?

Well if we had the ability to change things like Eye colour or Hair colour, then we could always change them back. Or, we might introduce new variations that could not have evolved naturally in the same span of time (they might have eventually been able to evolve, but it would have taken a far longer time).

[PhDP]

Evolution is rather simple. variation, reproduction, selection.

 

If it's so simple perhaps you can solve the Great Obsession, or perhaps you can explain how the different forces act on the genetic structure of population on the long term ? The fact is, many people here think evolution is what you described, but in truth, it's much more complicated.

 

I'd follow Lynch and say that if we have so much trouble with creationists, it's because we've created a strawman of evolution and got rid of all the maths.

 

So I guess my answer is while humans may be a pinnacle of evolution now

 

That sentence doesn't make any sense, there is no such thing as a pinnacle of evolution.

[lucaspa]

If the genetic modification isn't assisting the genome in reproducing then genetic diversity must be reduced.

 

No. Most loci (locations of genes) most of the time are neutral in terms of selection. They are at what is called Hardy-Weinberg equilibrium and the frequency does not change from generation to generation.

 

Evolution is rather simple. variation, reproduction, selection.

 

That is not "evolution" but rather natural selection. However, the sequence is variation, selection, reproduction.

 

So in evolution you can say that multicellular life was selected for, and is selected for.

 

Not exclusively. 99% of all species are still unicellular. A more accurate statement would be "there are ecological niches (ways of earning a living) for which being multicellular is better than being unicellular."

 

So I guess my answer is while humans may be a pinnacle of evolution now,

 

No, we're not. Every contemporary species has the same 3.8 billion year history of evolution. They are all descendents of evolutionary winners, just as we are. We have more technology, but that does not make us superior in an evolutionary sense.

 

only a minor percent of life in some form would be able to live on, vs. humans as a specie which I wager would go extinct.

 

In which case we were not "superior" in an evolutionary sense, much less "the pinnacle of evolution", were we?

 

Which would seem to make a strong case for not needlessly genetically modifying our children, on the grounds that we would be artificially selecting our future variations?

 

YES! Let natural selection work. It's smarter than we are.

 

The corollary of this, and the answer to the originating question then is: No, by artificially prolonging life we increase the genetic diversity in the population as a whole.

 

Interesting, I like!

 

Glad you do.

 

However, if instead you genetically modify that person's genome to eliminate that disease, then you still have the rest of that person's genome (you have kept the baby but thrown the bathwater out).

 

Possibly. Unfortunately, many things, including disease, are polygenic.

 

There are some genetic diseases (such as achrondroplasia or osteogenesis imperfecta) where you might be able to manipulate the genome of ovum and sperm to eliminate the disease. OTOH, you might also be able to cure the disease by just using manipulated some adult stem cells instead of messing with the reproductive cells.

[jimmydasaint]

No. Most loci (locations of genes) most of the time are neutral in terms of selection. They are at what is called Hardy-Weinberg equilibrium and the frequency does not change from generation to generation.

 

 

With respect, doesn't the Hardy Weinberg Law make some strong assumptions? For example small population size, negligible rates of mutation, no natural selection taking place, random mating, no immmigration or emigration from the population,,,(this is from memory so I hope this is right)

[PhDP]

With respect, doesn't the Hardy Weinberg Law make some strong assumptions? For example small population size, negligible rates of mutation, no natural selection taking place, random mating, no immmigration or emigration from the population,,,(this is from memory so I hope this is right)

 

It does... but it doesn't require the population to be small, on the contrary, if the population size is too small drift will get in the way. There are many important things to learn with the HW model; the frequencies will reach a stable equilibrium after one generation; you can track allele frequencies with the phenotype frequencies; even recessive alleles won't disappear (it wasn't so obvious back then)...

 

Of course, the main point of the HW model is that it doesn't work in the real world, because of selection, drift, migration, nonrandom mating, and it's why it's such an important model, it gives us the expected frequency in the absence of those forces.

[jimmydasaint]

It does... but it doesn't require the population to be small, on the contrary, if the population size is too small drift will get in the way. There are many important things to learn with the HW model; the frequencies will reach a stable equilibrium after one generation; you can track allele frequencies with the phenotype frequencies; even recessive alleles won't disappear (it wasn't so obvious back then)...

 

Of course, the main point of the HW model is that it doesn't work in the real world, because of selection, drift, migration, nonrandom mating, and it's why it's such an important model, it gives us the expected frequency in the absence of those forces.

 

Thanks for the clarification about population size. However, the next part is counter-intuitive to me - the model does not work anywhere in the real world yet it is still useful. So the model is actually not useful in a real world scenario except at predicting stable inheritance of recessive genotypes. There must be better models surely?

[PhDP]

Thanks for the clarification about population size. However, the next part is counter-intuitive to me - the model does not work anywhere in the real world yet it is still useful. So the model is actually not useful in a real world scenario except at predicting stable inheritance of recessive genotypes. There must be better models surely?

 

Let's say you have disease caused by a recessive allele "a" and you know that a proportion 'X' of people have the disease (let say; 0.01, or 1%), what is the frequency 'p' of the allele 'a' ? Using the HW law you have;

 

[math]AA = (1-p)^2[/math]

 

[math]Aa = 2pq[/math]

 

[math]aa = p^2 = X\mbox{, } p = \sqrt{X} = 0.1[/math]

 

So, assuming the allele is in HW equilibrium, the frequency of 'a' is 0.1 or 10%. In truth, the assumptions are likely wrong here, first because of migration, but also because many evolutionary forces could act on this allele. Still, the HW could be good enough. I shouldn't have said that it never worked in the real world, what I meant was that the underlying assumptions were likely wrong most of the time, but they can provide good estimates.

 

A more interesting application would be to detect nonrandom mating, for example if a population always, systematically deviate from the expected equilibrium while the frequency of the allele remain constant. Or if positive selection occurs, you could use the equation to calculate the change in frequency of the allele just by looking at the evolution of the phenotype.

Edited July 6, 2008 by PhDP

[theThinker]

by using medicine, and technology as a whole, to extend the lives of people who are not "strong" it may seem like we are weakening the species but in reality we are strengthening it.

 

it strengthens us by strengthening our technology which is humanities strength. our technology has separated us from the rest of the animal kingdom because while other animals adapted by changing them selves to fit the world we change the world to fit us. this has caused some problems but we are learning to use this ability responsibly.

 

in fact our technology is reaching the point were it seems the next stage of human evolution with be brought about by our own hands whether from genetic engineering, cybernetics, some other technology, or all of the above. this could lead the several different species of human.