Human devolution?

Question

I know "reverse evolution" is not a valid scientific statement, because evolution in essence has no direction. Yet, I can't help but using it in the layman's language to signify something related.

Developing societies have much higher birth rates than modern societies, this would usually be tempered with high death rates, but as medical technology improves/becomes more available, more and more people will be kept alive even though they are on the margins of society. This will sustain a continual population increase from developing nations, but modern societies will continue to depopulate (as most are, if they don't have lots of immigration). Isn't this a downward spiral, with no recourse? I know that people in developing countries are not "genetically" inferior to us, but sexual selection and culture are the main factors for reproductive success. Does this imply that humans are destined for self-sustaining mediocrity, or am missing the big picture?

Answer 1

Campfire stories? Is that what you call the incidents of the biblical Paradise?

Why are you certain that sexual selection (?) and culture (?) are the main factors for reproductive success?

Mediocrity is already here: you have  well contributed to it by analyzing such a subject in a poor, superficial way. You're referring to INVOLUTION, I suppose.

Answer 2

The rapid rise in human genetic disorders will probably end humanity in this century if nothing can be done. Studies have shown them to have gone from roughly 4500 in 1963 to over 12,000 in 1996.

"By 2031, it is estimated (R2 = 0.995) there will be 100,000 human genetic disorders and by 2096 1,000,000 (see Figure 3). “At least one clinical disorder has been related to 1,318 of the mapped loci (roughly 30%)” (McKusick, 1998, Vol. 1, xiii - xviii). That suggests genetic disorder saturation of each locus by 2031 and supersaturation by 2096.

These data confirm human devolution and suggest imminent permanent genetic extinction in this century."

http://www.csulb.edu/~jmastrop/data3.htm...

Answer 3

Evolution is not inherently progressive.  And the standards you apply to what is 'devolution' is cultural in nature.  By that I mean, humans may think something is genetically superior or inferior, but that doesn't make it so.  Nature decides which traits best fit the environment, and selects those traits.  Perhaps culturally we need to reevaluate what traits we label superior/inferior.

Answer 4

By keeping unfit organisms alive, you are also increasing diversity.  Another way diversity is increased is by increasing population.  Both are positive long term and likely counter the effect of less selection short term.

Answer 5

Dude, get a grip.  I can guarantee you that you had ancestors that were dirt poor and you turned out alright.

Answer 6

If you get the chance watch the movie "Idiocracy" ( i think thats how it is spelled ) but it has alot to do with your question.

Answer 7

Overall, yes, the trend is towards the genes of unsuccessful individuals increasing in prevalence inside of communities.  This isn't a commentary on developing societies having inferior genes--it's an observation inside of a society, whether it is developing or developed.

I think that there are a few other points worth exploring here:

1.  It is true that the selection pressures on humans have changed drastically over the past century.  

It's now possible for someone with a bad immune system to survive and thrive and reproduce, whereas previously (especially before sanitation became a known concern), that person would have probably died as a child from a disease.

It's now possible for someone who is blind or deaf to succeed equally with those who can hear/see, due to medical improvements and to societal changes (like putting braille on signs).

Though the genes aren't known for this, it's likely that intelligence (I don't mean IQ test intelligence, but the general term involving the ability to think critically and logically, to learn new skills, etc.) has a genetic component.  Most likely other skills that are necessary for surviving in our modern civilization do, too.  Our practice of charity allows even those who are unable to succeed in modern society to survive and reproduce.

2.  These changes in selective pressures are not actually changing (evolving) the gene pool of the human species.  

Because those with genes that say "bad immune system" or "blind" can have those genes show in up their children, and still have those children reproduce, those genes will become more common in the overall population.  In the same ways, those incapable of surviving in the current society without charity get aid and help.  

Now that these genes give no real advantage or disadvantage to those who have them, they are subject to general genetic drift, just like hair color or eye color.  

The frequency of those genes could increase or decrease randomly.  Over time, they could completely take over the gene pool so that good immune systems don't even exist anymore.  However, it could work in the reverse--the genes disappear naturally.  Most likely, the frequency just stays about the same over the years.

This isn't positive or negative evolution--it's a lack of change.

3.  Now we look at where children are being born, and who is giving birth to them.

Because more children are born to those in poor, underprivileged situations than those in rich, privileged situations, it follows that the next generation will have more "poor, underprivileged" genes.  Now you've stated that these people aren't genetically inferior to the "rich, privileged" people.  This means that the next generation, even though it has more genes from that group, isn't creating a new generation that is more mediocre than the previous one.  It's genetically equivalent--again, no change.

There has to be a difference between the genes of the group doing more reproducing versus the group doing less reproducing for any evolution to occur--either positive or negative.

What if we assume that while the vast majority of "poor, underprivileged" genes are genetically equivalent to "rich, privileged" genes, but that all of the bad genes are clumped in the poor group, while all of the rich group has almost no bad genes?  This would be a negative evolution then--over many, many generations the prevalence of the bad genes would increase.

What if we assume that there are different types of good and bad genes?  What if, overall, those in the rich group have genes that make them successful in our society--intelligence genes, or common sense genes?  What if, overall, those in the rich group also have genes for poor immune systems?  That means that our recent changes have increased the prevalence of "good" genes that are currently relevant versus "bad" genes that aren't currently relevant.

If we only take one country (instead of mixing different opportunities for advancement in here), we could easily say that the most intelligent and successful genes are decreasing in frequency, because the most intelligent and successful in most civilizations around the world tend to have less children.

4.  In the end, all that is occurring is that one group of people is increasing the prevalence of their genes, whereas another group's gene prevalence is decreasing.

This is a kind of evolution, as long as the genes between the two groups really are different.  It isn't even a positive or negative change as long as the differences are purely cosmetic.

Taking my above point--that inside of a region, the genes for intelligence and success are, overall, decreasing--then a negative evolution is currently occurring.  Does this imply that humans are destined to end up mediocre in these areas?

Until our culture changes, I think it does.  Taking time off for children is discouraged in the current climate in highly successful regions.  Women equally value their careers with their husbands, so while a society that doesn't allow women to work outside of the home would allow for successful men to reproduce while continuing to advance their careers, our current society doesn't make that easy.  A reverse society--women with careers, men stay at home--works in the same kind of way, except that it would require allowances for pregnancy.  Raising children is a difficult and time-consuming process, and each added child requires more time, money, and effort.  Pregnancy is hard on a woman's body, and multiple births can make it more and more difficult.  

A primary difference between the birth rate among the successful and intelligent and the unsuccessful and less intelligent is the use of birth control, too.  Most forms of birth control-condoms, pills-require regular and constant use to be effective.  They are also cheap on a day-to-day basis.  On the other hand, the choice of using an IUD instead, while more effective for someone who last the skill of remembering to take the bill, requires a significant early deposit of money.  The choice is often not presented to women, too.

Until the culture changes to inform all women and men of birth control options and how to use them, to where having multiple children is frowned upon, and to allow women and men to pursue their careers while raising a family, this trend will continue.

However, this is self-limiting.  If the unsuccessful genes are the only ones increasing, then there will be less and less successful gene-people to support them.  Eventually, it will hit a balance--where the successful group cannot fully support the unsuccessful group.  This creates a new selective pressure.

5.  The other important thing to consider is that the overall gene variety is increasing.

This is big.  In fact, this is huge, and it's wonderful.

Part of the theory of how evolution occurs (in a simplistic manner) is that a species hits a nice, mild stage where all sorts of different forms can thrive.  Then, a selection event occurs, killing off the old form, but allowing one of the new, different forms to survive.

Gene variety increases the overall chance of survival of the species and whatever species develop from humans.  We don't "see" a selection event in our future, but it isn't impossible to have one.  Famine and drought are two good examples of a type of event.  Disease is another good example.

Sometimes gene forms that we don't see as advantageous actually turn out to be good, too.  A good example is sickle cell anemia and malaria.

Sickle cell anemia is bad.  It's carried as a recessive gene, so having a good copy and a sickle cell copy isn't a problem, but it does decrease the survival/reproductive chances of your children if they happen to get two recessive copies.  Overall, we would predict that this gene would decrease in frequency over time.

However, it was noticed that in Africa, there is a VERY high presence of the sickle cell gene.  This doesn't make sense--while medical conditions have improved in Africa, they aren't good enough to remove the dangers from sickle cell anemia.  In fact, it isn't a safe condition to have in any region of the world.

It turns out that having one copy of the sickle cell gene and one copy of the normal gene provides a resistance to malaria.  While a smaller percentage of their children will end up thriving, the individual with two different copies has a significantly increased chance of survival themselves.

6.  The rate of genetic change may differ between the different groups.

It's easy to imagine that the poor live in areas that are more likely to be near a toxic waste dump, that they are less likely to avoid harmful mutagens in food, etc.  Of course, at the same time, medical practices such as X-Rays can cause mutations, as can many drugs or fancy new synthetic (and natural) food products.

However, it's also easy to imagine that in the end, one group is exposed to significantly more mutagens than the other group, and that this group is thus more likely to develop new genes.  New genes are, on average, negative for the individual.  However, they're also they only way to really develop new traits.  This is more of a side-bar than a response to the issue of devolution, mostly because it's impossible to link mutation rate to either group currently.

Answer 8

It really is not all true you should try to read the Bible in Genisis 1:1