Is Human Evolution Limited by Physical Constraints?

[Hwarang]

Evolution works like this-

You get a whole lot of people. Then put them in some environment and let them live there. If the environment is safe and warm than survival is easy. If the environment is hell then natural selection kicks in. Only the smart or strong or both will survive. The smart or strong will continue breeding eventually a genetic mutation occurs which creates a human that is slightly different than the other humans. This might give the guy or gal a slight edge in surviving as well as getting mates. Because of this that mutant will mate a lot more often and spread his/her genes. In turn the offspring might also possesses this advantage and breed more easily as well. Eventually several mutations will occur over millions of years until they become different species.

So yes, we are evolving. Unfortunately evolution does not mean that you will evolve into a higher form of life. We are actually devolving. According to statistics the people who reproduce the most often happen to be the criminals and low IQ people. Due to birth control products(smart people are more successful with them) and the fact that smarter people choose to have less children the IQ average of most of the worlds is dropping. Yes, we are getting dumber. The weak and dumb are allowed to live. This also means that a chance of a negative genetic mutation is much greater than a positive mutation. It also means that the a negative mutation will also be able to survive due to liberal society.

Of course this will take millions of years and by then humans will have either

A. blown ourselves out of the water.
B. Something blows us up
C. We genetically create supermen using technology

IQ and brain size is dropping in American faster than any other race or group has in history.

An average of 0.7 IQ points is being lost in whites, even more points is lost for blacks due to larger percentage of criminals. Of both races, criminals and low IQ people mate the most often. This is the exact opposite of the world over 100 years ago where only the smart and successful had lots of children. The people who also get abortions tend to be able to pay for them. Our IQ might level off until we hit the low 70s -60s possibly 50s in several hundred years if we don’t do something about it. An IQ that low does not mean your mentally retarded with the inability to talk and walk properlly. You can still function in society with an IQ in the 50s-70s, its just that your mental age would be the equivalent of say an average 5-8 year old.

Of course if averages continue like that, civilization will collapse and survival of the fittest will occur raising averages again.

 

[Evo]

Evolution works like this-

You get a whole lot of people. Then put them in some environment and let them live there. If the environment is safe and warm than survival is easy. If the environment is hell then natural selection kicks in. Only the smart or strong or both will survive. The smart or strong will continue breeding eventually a genetic mutation occurs which creates a human that is slightly different than the other humans. This might give the guy or gal a slight edge in surviving as well as getting mates. Because of this that mutant will mate a lot more often and spread his/her genes. In turn the offspring might also possesses this advantage and breed more easily as well. Eventually several mutations will occur over millions of years until they become different species.

So yes, we are evolving. Unfortunately evolution does not mean that you will evolve into a higher form of life. We are actually devolving. According to statistics the people who reproduce the most often happen to be the criminals and low IQ people. Due to birth control products(smart people are more successful with them) and the fact that smarter people choose to have less children the IQ average of most of the worlds is dropping. Yes, we are getting dumber. The weak and dumb are allowed to live. This also means that a chance of a negative genetic mutation is much greater than a positive mutation. It also means that the a negative mutation will also be able to survive due to liberal society.

Of course this will take millions of years and by then humans will have either

A. blown ourselves out of the water.
B. Something blows us up
C. We genetically create supermen using technology

IQ and brain size is dropping in American faster than any other race or group has in history.

An average of 0.7 IQ points is being lost in whites, even more points is lost for blacks due to larger percentage of criminals. Of both races, criminals and low IQ people mate the most often. This is the exact opposite of the world over 100 years ago where only the smart and successful had lots of children. The people who also get abortions tend to be able to pay for them. Our IQ might level off until we hit the low 70s -60s possibly 50s in several hundred years if we don’t do something about it. An IQ that low does not mean your mentally retarded with the inability to talk and walk properlly. You can still function in society with an IQ in the 50s-70s, its just that your mental age would be the equivalent of say an average 5-8 year old.

Of course if averages continue like that, civilization will collapse and survival of the fittest will occur raising averages again.

Actually IQ is increasing, your information is inaccurate. Yes, I have the data to back that up, I just don't have the time to dig it out right now. It's already been posted in other threads here.

edit: Here's one I just found (I'm not on my usual computer and don't have access to my bookmarks). "A line on a graph corresponding to test scores climbs steadily from 1930 to 1990. In just 60 years, the IQ of the average person in the United States has gone up almost 20 points."
http://www.rps.psu.edu/0309/iq.html

 

[Bartholomew]

From what I've read, fluid IQ (reasoning skill) has been increasing, and static IQ (knowledge) has been decreasing.

 

[Chronos]

Evolution works like this-

You get a whole lot of people. Then put them in some environment and let them live there. If the environment is safe and warm than survival is easy. If the environment is hell then natural selection kicks in. Only the smart or strong or both will survive. The smart or strong will continue breeding eventually a genetic mutation occurs which creates a human that is slightly different than the other humans. This might give the guy or gal a slight edge in surviving as well as getting mates. Because of this that mutant will mate a lot more often and spread his/her genes. In turn the offspring might also possesses this advantage and breed more easily as well. Eventually several mutations will occur over millions of years until they become different species.

So yes, we are evolving. Unfortunately evolution does not mean that you will evolve into a higher form of life. We are actually devolving. According to statistics the people who reproduce the most often happen to be the criminals and low IQ people. Due to birth control products(smart people are more successful with them) and the fact that smarter people choose to have less children the IQ average of most of the worlds is dropping. Yes, we are getting dumber. The weak and dumb are allowed to live. This also means that a chance of a negative genetic mutation is much greater than a positive mutation. It also means that the a negative mutation will also be able to survive due to liberal society.

Of course this will take millions of years and by then humans will have either

A. blown ourselves out of the water.
B. Something blows us up
C. We genetically create supermen using technology

IQ and brain size is dropping in American faster than any other race or group has in history.

An average of 0.7 IQ points is being lost in whites, even more points is lost for blacks due to larger percentage of criminals. Of both races, criminals and low IQ people mate the most often. This is the exact opposite of the world over 100 years ago where only the smart and successful had lots of children. The people who also get abortions tend to be able to pay for them. Our IQ might level off until we hit the low 70s -60s possibly 50s in several hundred years if we don’t do something about it. An IQ that low does not mean your mentally retarded with the inability to talk and walk properlly. You can still function in society with an IQ in the 50s-70s, its just that your mental age would be the equivalent of say an average 5-8 year old.

Of course if averages continue like that, civilization will collapse and survival of the fittest will occur raising averages again.

That might be the most amazing post I've ever seen - notice I did not use the word intelligent. Evolution does not work that way.

 

[hitssquad]

Conversion of adult IQ to mental age

Our IQ might level off until we hit the low 70s -60s possibly 50s in several hundred years... An IQ that low does not mean your mentally retarded with the inability to talk and walk properlly.

An IQ below 70 would be in the mentally-retarded range.

--
mental retardation is generally thought to be present if an individual has an IQ test score of approximately 70 or below.
--
http://www.aamr.org/Policies/faq_mental_retardation.shtml

Adult dogs typically have adult-human-equivalent IQs of below 20. It can be observed that they can typically walk and run with great agility. Typical 4-year-old humans have adult-equivalent IQs of 25. It can be observed that they can typically walk well.

You can still function in society with an IQ in the 50s-70s, its just that your mental age would be the equivalent of say an average 5-8 year old.

--
In adults, an IQ of 50 approximately represents the intellectual capacity of the average eight-year-old, who is able to read simple texts and do simple arithmetic but is not capable of functioning independently.
--
(Richard Lynn. . p65.)

--
Among adults, an IQ of 35 is approximately equivalent to a mental age of 5 1/2 years...
--
(Ibid. p98.)

--
An adult with an IQ of 56 has a mental age of nine years, that is to say, has the abilities of the average nine-year-old. The average nine-year-old can read popular newspapers with ease and make sensible suggestions for the solutions to simple crossword puzzles.
--
(Ibid. p223.)


In other words, a typical 100-or-below IQ-score for an adult can be transformed into mental age by multiplying by 0.16 (or by dividing by 6.25).

Adult IQ     Mental Age (of)

6.25         1 year
12.5         2 years
18.75        3 years
[b]25           4 years[/color][/b]
31.25        5 years
37.5         6 years
43.75        7 years
[b]50           8 years[/color][/b]
56.25        9 years
62.5        10 years
68.75       11 years
[b]75          12 years[/color][/b]
81.25       13 years
87.5        14 years
93.75       15 years
[b]100         16 years[/b][/color]

 

[Hwarang]

Oh no, your wrong, births today are hitting the dysgenic path.

http://www.eugenics.net/papers/eb8.html
http://www.eugenics.net/papers/evidence.html

Notice that the average criminal has lower IQ than the median, they also reproduce the most often. Also notice that the smartest people are the most successful in using birth control products. They are also wealthy enough to afford abortions. The low IQ and even criminals reproduce more often

Also an IQ rise from the early and mid 1900s is not surprising. People were being fed more and more access to schools due to people moving out of farms and into cities with better education. Today however there is no excuse for dropping IQ points. In the early 1900s as well, the rich people also had lots of offspring so it leveled off. However with the mass introduction of birth control products the situation has changed.

And to the other guy, mind telling me what “correct” evolution is then?lol

 

[Phobos]

We are actually devolving.

Note that there is no such thing as "de-evolution" (that would imply an erroneous march-of-progress model). Evolution is simply change. A population's characteristics will shift toward whatever best survives. For example, whales did not "devolve" legs and revert back to fish fins in their transition from land to sea...they evolved something new (although similar, given the similar environment). Evolution does not proceed up and down a particular genetic scale...it produces variations in populations that are put to the test.

And a footnote on the IQ discussion...IIRC, an IQ of 100 is defined as "average". So, even if we were 50% smarter/dumber, the average would still be 100. Of course, we can still talk about relative IQ changes.

 

[guevaramartyr]

think about what type of evolution you are discussing. micro evolution (changes within indivduals or a species) is certainly occurring (resistance to disease, height change, etc) while macroevolution (change from one species to another) is much more vague. extreme mutations that usually die aside, i haven't heard of any human that cannot breed with another member of the species so far.

 

[Ouabache]

I'd like to add a couple of examples of genetic mutations and their impact on human evolution.

I remember from a genetics course, the gene responsible for sickle cell anemia (HbS), also confers some immunity to malaria (which can come in handy if you lived where malaria is common). If you carried both alleles of the sickle cell gene, your chances of survival diminish due to anemia. However if you carry only one sickle cell allele and the other is normal (heterozygous genotype), you have a much better chance of surviving malaria and reproducing. Those not carrying this mutation, are more likely to die from malaria.
If you're really curious about how this sickle gene is beneficial in resisting malaria see ---> http://www.pbs.org/wgbh/evolution/library/01/2/l_012_02.html

Another mutation that has entered our gene pool is \delta32 mutation on gene CCR5. This mutation has been found to exist in the human genome at least for 4,000 years. Those who were carrying it in Europe during the Black Plague epidemic in the 14th century, were immune to plague and survived to pass along their genome to future generations. Today it has been found that those who carry this same mutation, when infected by HIV, have a strong resistance to AIDS. (the mechansim for resistance is also similar to black plague, preventing infection of white blood cells).

In terms of evolution, these and various other mutations have provided a means of survival of humans under hostile environments. Granted these conditions were not global, but if they were, we have the means to survive to another generation.

As a species, we are still only newcomers on the block, having been around a mere 30,000 years... Before us, Neanderthal (Homo neaderthalis) was the dominant hominid for 170,000 years. It is likely, in the course of evolution, that we are not the last hominid to populate the world.

 

[Billy T]

I like to add a couple of examples of genetic mutations and their impact on human evolution. ...gene responsible for sickle cell anemia (HbS), also confers some immunity to malaria...Another mutation that has entered our gene pool is \delta32 mutation on gene CCR5. ...Those who were carrying it in Europe during the Black Plague epidemic in the 14th century, were immune to plague ...As a species, we are still only newcomers on the block, having been around a mere 30,000 years... Before us, Neanderthal (Homo neaderthalis) was the dominant hominid for 170,000 years. It is likely, in the course of evolution, that we are not the last hominid to populate the world.

I knew of first alredy, but not the second. In attachment, I offer a different type of mutation which may explain why we dominated all other humanoids so quickly, doing in even the bigger brained and much stronger Neanderthals. It explains a lot of other things as well. What do you think of this idea?

 

[Hwarang]

Usually the bigger and denser your bodies are the more brain tissue is needed to control bodily function. This explains why taller people have larger brains than shorter people yet that doesn't make them smarter.

Neanderthals were the warrior class of the hominids. Their bones were much thicker and denser than ours. Their muscles were much heavier and strong. Their nose was shaped uniquely. I guess due to all this heavy body functions they needed larger brains to control bodily function. Brains also differ differently. A brain with more vein like connections will be much more efficent and "smarter" than a brain of equal size yet less sophistication. I guess Neanderthals didnt have the connections necessary to compete with humans.

However one thing people seem to forget is that during the prime of the Cro Magnons, the Cro Magnons averaged brains 25% larger than todays Europeons. Other human groups in the past had brains as larger or larger than the Cro Magnons. I am guessing Humans back then had brains larger than Neanderthals.

 

[Gold Barz]

Could neanderthals have, if they were never wiped out and we were the ones who did, developed similar to us obtaining human-like intelligence?

 

[nipwoni]

Have you considered Hardy-Weinberg Equilibrium? If a population is in "equilibrium," it is not evolving at all. There are 5 requirements for a population to be in equilibrium:
1. No natural selection
2. No sexual selection (all mating is completely random and all individuals produce the same # of offspring)
3. No net mutation (any mutations that do happen are canceled out by mutations in the opposite direction)
4. No migration into or out of the population
5. The population is infinitely large (so genetic drift has no effect)

The human population does not meet any of these requirements except #4, so it must be evolving. In fact all populations are evolving since it is impossible to meet all of them.
This only applies to microevolution though.

 

[Phobos]

Could neanderthals have, if they were never wiped out and we were the ones who did, developed similar to us obtaining human-like intelligence?

It's possible, but not a necessary next step. (i.e., they could have kept evolving in many different ways, but there's no set path to our intelligence)

For what it's worth, Neandertals are considered to be "human" too...just a different species of human (genus Homo).

 

[nipwoni]

Neandertals are actually part of the same species as us- they were Homo sapiens neandertalis. Anthropologists think they could have interbred with Cro Magnons, although I think the current consensus is that they didn't contribute much to our gene pool, if at all.
Also, their large brains probably went along with high intelligence, probably as high as ours though in different ways. Certain parts of their brains were larger than ours and certain parts smaller. So, since their intelligence had a different emphasis from ours, they likely would have evolved down a different path.

The Cro Magnons back then did not have larger brains than the Neandertals. The Neandertals had the largest brains (even compared to their body size) of any hominids.
I don't think there's any evidence to show that Neandertals had less connections in their brains than modern humans. I think the main reason they died out was because they were so adapted to the northern European ice age climate. They had to survive in a very harsh, extreme environment, and were successful for hundreds of thousands of years. But they were so specialized that they couldn't compete with a newer, more flexible form, Homo sapiens sapiens, when we started to spread into Europe.

Something many people don't realize is that there have been many species and subspecies of hominids and humans over the last 7 million years or so, often more than one at once. Sometimes they managed to coexist, but usually one outcompeted the other. This means that we are probably not the last species of human. Eventually something in the environment will change and force us to change too, or one group of humans will branch off and become something new, and Homo sapiens as we know it will disappear. So, just because a species went extinct doesn't mean it was a failure. It will probably happen to us someday, and many of those species lasted much longer than we have so far.

 

[Billy T]

...Something many people don't realize is that there have been many species and subspecies of hominids and humans over the last 7 million years or so, often more than one at once. Sometimes they managed to coexist, but usually one outcompeted the other. ...

You obviously know more about this than I do (assuming you are not just making things up), but I am impressed by the "Out of Africa" event of approximately 50k years ago. Nothing like it had happended in several million prior years - (rapid expansion of one small group to domonate/ eliminate all others).

I am obviously biased as I think it may be related to the strange view I hold about perception in the attachment. What do you think? Why, in less than 20k years, was it all over for the "others"?

 

[SaPhZ]

We will get less intelligent; Studies show that University graduates are far less likely to have children.

 

[selfAdjoint]

We will get less intelligent; Studies show that University graduates are far less likely to have children.

It is a fallacy that because the people who exhibit a trait have fewer children therefore the number of people in the population who exhibit that trait will decrease. Even for a single Mendelayev trait, with alleles B and b, where the recessive variation requires a bb gene match to be displayed, having the bb bearers create NO children would still leave half the population (the Bb's) carrying the gene, under equilibrium, and from their mating new bb individuals would continue to be born at a stable rate. Intelligence is evidently caused by a number of genes, so the number of people carrying the necessary recessives would be even larger.

In the middle ages of Europe, the intelligent boys were systematically steered into the monasteries, where they did not contribute to the next generation (only the somewhat less intelligent became parish priests who often cohabited and had children). But when the renaissance came there was no dearth of intelligent people from that strong anti-intelligence non-breeding program.

 

[matthyaouw]

Also- Who is to say that intelligence is brought about by genetics rather than upbringing?

 

[1123581321]

I've got myself into a debate about whether Evolution is currently occurring in Humans.

So far, with my initial thoughts on the subject, no matter how I approach the topic, I can only formulate Affirmative arguments. Can anyone think of any sort of case that can be built against the stance that humans are currently evolving just like everything else?

(Even if you need to 'select' your definitions, choose your versions of evolution, your types of selection or whatever...)

if you go back in history, 200-300 years ago the mid 5 foot range was normal for humans, George Washington was 6'5", which was very, very tall for back then. Is this evolution, or are we just finding better food and nutrition to make us taller?

Fibonacci

 

[hitssquad]

Fixing of biological traits - possible or impossible

Even for a single Mendelayev trait, with alleles B and b, where the recessive variation requires a bb gene match to be displayed, having the bb bearers create NO children would still leave half the population (the Bb's) carrying the gene, under equilibrium, and from their mating new bb individuals would continue to be born at a stable rate.

Are you saying the fixing of traits in biological populations is impossible?

 

[Phobos]

Neandertals are actually part of the same species as us- they were Homo sapiens neandertalis.

There has been a debate as to whether Neandertals were a subspecies (as you say) or a separate species (H. neaderthalensis). My understanding is that the mainstream view is that Neandertals were a separate species.

 

[Hwarang]

George washington was tall because he had good nutrition and was lucky enough to receive better height genes. We arnt growing taller though. The Human genome has a maximum limit to how tall we can get. I am estimating the maximum height to be about 7,8 for males and 7,2 for females. Despite this maximum its still possible to get even taller if you suffer from that pituatary gland abnormality(the gland over produces human growth hormone). For example Robert Wadlow who suffered from that condition grew to be 8,11 whiles his genes probally told him that he was only suppose to be around 5,8 in height. Because of this he suffered horrible knee problems and died during his early 30s.

In the future we might see some 1st world nations reach their maximum height with people average in the 7 foot range. This is unlikely though, as height on that range produces a lot of disadvantages.(Buildings will have to be completely re-constructed to accommodate the new taller people, people of that height will have to consume much more food and energy in a world of limited energy and resources, height in that range is much harder to work in and much more clumsy for daily works). In fact I think height will probally decrease in the far future to the 5,5 or less range. I am serious here. Smaller people will consume less resources than much larger people. Which means there will be more smaller people. Which means more brains which means more innovation.

Height for modern first world nations will probally level off at 6,3-5,10 average for males unless a eugenics program is introduced to to purposely increase height to the 7 foot range. Of course certain groups will have taller averages and max heights. Africans will be the tallest. In fact the Tutsi's in Africa averages over 7 foot in height during their peak after selective breeding.

Oh yeah and I found a interesting link regarding neanderthals.

http://en.wikipedia.org/wiki/Homo_neanderthalensis

it says that neanderthals had brains 10% larger than modern humans today. Which is impressive, however the cro-magnons for example had brains 25% larger than modern humans. And don't forget that neanderthals had stronger, heavier bodies which meant more brain was needed to control bodilly functions. Another way to measure intelligence was comparing the tools both sides made. If I remember correctly, the humans made much better tools and had a advantage of unique throwing spearings fire with some wooden shaft which neanderthals didnt. Also there has yet to be a single human with neanderthal genes in them. Neanderthals and Humans could not mate.

 

[tobias087]

I think that because of modern circumstances, some of the conventional rules of evolution will have to be thrown out the window. For example, in the above predictions about the evolution of height in man in the future, it's assumed that reaching a maximum height is economically undesireable because it puts a strain on resources (ie. tall people need to eat more).

However, while this might be a factor for animals in the wild with scarce food supplies, man, in developing countries at least, has no such scarcities. Most people simply do not die from starvation in developed countries in a systematic way caused by food scarcity. If people are hungry, they can easily find more food, at very small marginal cost. Evolutionary economics are a thing of the past. (Not to imply that there aren't hungry people, but even the homeless don't usually die of starvation)

What we should do to examine current trends in evolution is go back to first principles. It would be tempting to list causes of death and declare that humanity will evolve to be less susceptible to these, there's a fundamental flaw there: most of the current leading causes of death (heart disease, cancer, stroke, etc.) are not things that kill people before they have had children. If a cause of death systematically ends people's lives after they've reproduced, then there is no selection pressure to develop immunity to it.

The better approach would be to consider causes of death in the age bracket where people have not yet had children. In the USA for ages 15-24 (which is below the average age of becoming a parent of 25) the leading cause of death is accidents, and the leading type of accident is car accidents, which account for 25% of deaths in this age group. Since food economics are no longer an issue (or are at least only a minor one) we should expect then that people will develop traits that help them survive car crashes (possibly thicker bones or something like that), since that is the main selection pressure in the developed world.

As with regard to the claim that humans are currently in stasis, in between phases of relatively fast evolution, that makes little sense. What we should expect in evolutionary trends is for organisms to evolve to the point where they are best matched for their environment. Then, if the environment stays constant, phenotypes should tend to stay constant since there is no natural selection impetus, disregarding sexual selection and drift. In humans, we do NOT see a constant environment. In fact, our environment has been changing spectacularly rapidly in the last few thousand years (and even faster in the last few hundred). We should expect then, that humanity will evolve rather quickly to meet its new challenges.

Sorry about the long post! Just had a lot to say.

 

[DaveC426913]

Sorry about the long post! Just had a lot to say.

And only five years late...

 

[tobias087]

haha, no time like the present

 

[Bodicea]

I would think that there must be a limit to certain aspects of evolution within the human body. Eg. height. If we evolve into heights of 7 or 8' then how will the heart cope with it. personally I think there is a limit to how tall we can grow.

Intellect? apprently our brains are growing bigger, and its occurred over the last 100 years, but the skull hasnt grown, so the brain is liimited by the the size of the skull, which in turn is limited by the size and strength of the neck. So imho, we are limited physically and intellectually...

However, how we use what we have is changing, and there may well be huge room for development in that area...Are our children actually smarter, or, are they using their brains in a different way due to all the technology that is around. From a very young age they are learning to hone incredibly spatial awareness, hand eye coordination via games consoles...

So, even though there may be physical limitations to our evolution, I'd say there is definte potential for evolution within the confines.