Are human beings done evolving?


by The_Absolute
Tags: beings, evolving, human
The_Absolute
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#1
Dec6-09, 06:50 PM
P: 182
Is the homo-sapien the final stage of human evolution? I've heard of a hypothetical "homo-superior," but I'm not sure if that is actual science or pseudoscience.
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mgb_phys
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#2
Dec6-09, 08:09 PM
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Quote Quote by The_Absolute View Post
Is the homo-sapien the final stage of human evolution?
No.
But remember that evolution isn't aiming at superior - it's aiming for more babies. So you might be evolving to be immune to the pill

I've heard of a hypothetical "homo-superior," but I'm not sure if that is actual science or pseudoscience.
The term is a bit pseudoscience, you would presumably be able to mate with it - so it's not really a new species.
hamster143
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#3
Dec6-09, 09:14 PM
P: 986
The key mechanism of evolution is natural selection. Natural selection means that a significant number of newborns in the species must either die before reaching adulthood, or fail to create offspring for whatever reason. That way, the fittest survive and mate, and the unfit die childless.

That's the way things work in the animal world, and that's the way things worked in the human world up until 1800 or so.

Starting around 1800, first developed countries started hitting the early stages of what came to be known as "demographic transition". It's a transformation of society from high birth-rate, high death-rate (think 8 children/woman, infant mortality 20%, etc. - ugly) to low birth-rate, low death-rate (1.5 children/woman, infant mortality zero). Once the demographic transition is complete, evolution stops. It stops because children no longer die and there are enough mates for anyone who's willing to mate. In some sense, what we have now is de-evolution of sorts - because intelligent and successful people voluntarily have fewer children than welfare moms.

The same transition process is underway in almost all developing and third-world countries, it started much later (1950's or so), but it's going at a faster rate and within 50 years many third-world countries will join us at the dead end of the evolutionary tree.

russ_watters
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#4
Dec6-09, 09:30 PM
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Are human beings done evolving?


Quote Quote by hamster143 View Post
Once the demographic transition is complete, evolution stops. It stops because children no longer die and there are enough mates for anyone who's willing to mate.
No. That doesn't eliminate competition for mates, nor does it address the impact of other impediments to mating, such as health issues.

Evolutionary pressures may function differently today than a few hundred years ago, but they still function.
xxChrisxx
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#5
Dec6-09, 09:36 PM
P: 2,032
Evolution has no goal, therefore it has no end.

It's merely change over time through natural selection.

In some sense, what we have now is de-evolution of sorts - because intelligent and successful people voluntarily have fewer children than welfare moms.
There is no such thing. Evolution is change. It doesn't state the change has to be good.


It's interesting to note that technology had skewed things slightly with regards to evolution. We have developed to a point where we no longer adapt to our surroindings, we adapt our surroundings to suit us. Whether long term this will make any difference what so ever, is yet to be seen.

for example, both my fiancee and I are very short sighted. In the past this would have put us at a significant disadvantage, but thanks to technology it's no longer such a huge problem.
hamster143
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#6
Dec6-09, 10:40 PM
P: 986
There is no such thing. Evolution is change. It doesn't state the change has to be good.
Normally, evolution implies adaptation for the environment. What we have is a process that makes humans as a whole less adapted to function in the modern environment, because those least adapted have children and those most adapted do not.

Of course, if you wish to define evolution as any kind of change, that is evolution.

That doesn't eliminate competition for mates, nor does it address the impact of other impediments to mating, such as health issues.
You can say that it slows significantly. Competition for mates is not eliminated, but we're at the point where it no longer plays any selective role. In a wolf pack, an alpha male wolf would mate with all the females of the pack and an omega male would not get to mate at all. There's strong advantage to be an alpha male. In a modern human society, 95 out of 100 end up married and having children (or not, depending on their preferences), and their children have close to 100% chance of surviving to adulthood.

Impediments to mating are few and far between, and, thanks to our modern medicine, things that would've been major impediments to mating, and sometimes even life, such as Down's syndrome or haemophilia, are no longer such.
alxm
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#7
Dec6-09, 10:55 PM
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Yes, there's this pervasive but wrong idea that evolution somehow has a 'goal' and that there's some kind of universal criteria in nature for what's better or worse.

Evolution doesn't stop, go forward, or go backward. It just happens, and depending on natural selection and the environment, things may change or not. If you think a certain development is good or bad, those are your values, not Evolution's. Why is smarter better? It doesn't seem like Nature has put a big premium on that particular trait. Why not, say, stability? In which case, horseshoe crabs are superior to us. Or all-around hardiness? Then cockroaches are better.

The other pervasive mistaken tendency, is to assume that Evolution works in terms of properties we think are important properties. Things we think are important are sometimes a mere side-effect in evolving some less obvious trait that happens to be more important to survival. Or perhaps just a result of a chance event in our evolutionary history. (Blond hair may only exist because of an ice age)

Sure, we'd all like to have more intelligence, all else being equal. But we don't know that all else can be equal! We don't know how intelligence works or how it's related to genetics, so we simply don't know what the trade-offs would be.
xxChrisxx
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#8
Dec6-09, 11:43 PM
P: 2,032
Quote Quote by hamster143 View Post
Normally, evolution implies adaptation for the environment. What we have is a process that makes humans as a whole less adapted to function in the modern environment, because those least adapted have children and those most adapted do not.

Of course, if you wish to define evolution as any kind of change, that is evolution.
Evolution does not progress to criteria YOU select as desirable, or what YOU consider to be 'most adapted'.

And what I said isn't my definiton, it's the scientific definiton.
"In biology, evolution is change in the genetic material of a population of organisms from one generation to the next."

"In the broadest sense, evolution is merely change, and so is all-pervasive; galaxies, languages, and political systems all evolve. Biological evolution ... is change in the properties of populations of organisms that transcend the lifetime of a single individual. The ontogeny of an individual is not considered evolution; individual organisms do not evolve. The changes in populations that are considered evolutionary are those that are inheritable via the genetic material from one generation to the next. Biological evolution may be slight or substantial; it embraces everything from slight changes in the proportion of different alleles within a population (such as those determining blood types) to the successive alterations that led from the earliest protoorganism to snails, bees, giraffes, and dandelions."

- Douglas J. Futuyma in Evolutionary Biology, Sinauer Associates 1986
"In fact, evolution can be precisely defined as any change in the frequency of alleles within a gene pool from one generation to the next."

- Helena Curtis and N. Sue Barnes, Biology, 5th ed. 1989 Worth Publishers, p.974
Sorry!
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#9
Dec7-09, 12:24 AM
P: 571
Quote Quote by xxChrisxx View Post
Evolution does not progress to criteria YOU select as desirable, or what YOU consider to be 'most adapted'.

And what I said isn't my definiton, it's the scientific definiton.
"In biology, evolution is change in the genetic material of a population of organisms from one generation to the next."
Well put. It should be noted not everything hamster has said is wrong however. Yes natural selection is not a major driving force for human evolution. This does not however mean that evolution has stopped, merely it's slowed down... gotten more refined. Take for instance: The gene CCR5-32, this offers resistance to HIV-1.

@OP, Yes evolution is always going. It used to be a common held position that human evolution stopped around 50,000 years ago. Prior to this 'races' as we know today had not developed yet. The reason the position was held was to ensure in public light that all races are equal... it's more of a political stance than scientific but I'm sure you understand the consequences of saying for instance that 'the --- race evolved further than the others', or 'the --- race evolved this which is better than --- race.' Just leads to a lot of non-sense.

However back when I took anthropology we learnt that humans have indeed evolved, even our modern species has evolved. We humans now are homo-sapien-sapien. There was another sub-species of homo-sapiens, I have forgotten the term but they went extinct.

Research has indicated that modern humans are still evolving, look up these genes: microcephalin, ASPM(All CAPS; so not Aspm), the gene I spoke of earlier CCR5-32, HLA-B27... there are a bunch more.

As well there is such a term as 'reverse evolution' it's not very popular but some people do use it and it does exist out there. It came out when we begun asking this very question, 'if we are still evolving and what effect does technology have on evolution.' Since babies who should have died have been allowed to live we are 'going against' evolution. The argument in this case isn't that evolution has a direction or a goal but we are fighting against evolution entirely but not allowing it to fully take its course. This term is of course up for debate and I'd rather not take a stance on it...

Here are some links to those genes I spoke of incase you didn't feel like looking for them yourselves:
CCR5 http://en.wikipedia.org/wiki/CCR5#CCR5-.CE.9432
ASPM http://en.wikipedia.org/wiki/ASPM_%28Gene%29
Microcephalin http://en.wikipedia.org/wiki/Microcephalin
HLA-B27 http://en.wikipedia.org/wiki/HLA-B27 (This is a 'protected' variant of th HLA-B gene which allows females to better clear HIV infection than those with HLA-A or C gene variants.)

A better question in my opinion is if we well ever face more speciation. Absent large external pressure I highly doubt we will see any further speciation... but things can't stay perfect forever . I wonder if we will ever see speciation occur during our 'scientific observational period' if you will. (so from ancient history to the future when we have been using scientific methods to observe and not just based on fossils...)
hamster143
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#10
Dec7-09, 03:55 AM
P: 986
Take for instance: The gene CCR5-32, this offers resistance to HIV-1.
Yes, this is a genuine example of evolution. It is also an excellent example why evolution is much slower today than a few hundred years ago.

If HIV-1 epidemic were to start in 1500, within 50 or 100 years the entire world's population (except Australia and some Oceanian islands) would've been infected. Any resistance gene would've offered significant survival advantage to its carriers, those without it would've died out, and within another 100 years it would've gone from an obscure gene to something nearly universal.

Today, less than 1% of the population even gets infected to begin with (thanks to the sex-ed and public outreach), which greatly reduces the significance of the gene, and we can hope to find a cure or a vaccine that stops the virus completely, without need for evolution.

A better question in my opinion is if we well ever face more speciation. Absent large external pressure I highly doubt we will see any further speciation... but things can't stay perfect forever .
One crucial requirement for speciation is to have multiple groups evolve in genetic isolation from each other. And even then speciation is mind-numbingly slow. Australian aboriginal peoples and Europeans have been evolving in relative isolation from each other for about 50,000 years, and yet they do not constitute separate species (they interbreed easily and give fertile offspring).

Hypothetically speaking, we could very well see some speciation if we try to colonize the galaxy using sub-light ships. A population of humans evolving in isolation on some remote planet that takes ten or twenty years to reach from the nearest other star, exposed to unusual threats (toxins, bacteria, radiation), could very well speciate off in a few thosands of years, especially if they "go native" and reverse the demographic transition.
russ_watters
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#11
Dec7-09, 07:35 PM
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Quote Quote by hamster143 View Post
You can say that it slows significantly. Competition for mates is not eliminated, but we're at the point where it no longer plays any selective role.
No! Competition for mates is everything, even with humans. Just because there are equal numbers of males and females, that doesn't mean everyone gets the mate they want or even necessarily mate at all! That's absurd.
In a wolf pack, an alpha male wolf would mate with all the females of the pack and an omega male would not get to mate at all. There's strong advantage to be an alpha male. In a modern human society, 95 out of 100 end up married and having children (or not, depending on their preferences), and their children have close to 100% chance of surviving to adulthood.
So then not all mate....so then evolution still matters....
Impediments to mating are few and far between, and, thanks to our modern medicine, things that would've been major impediments to mating, and sometimes even life, such as Down's syndrome or haemophilia, are no longer such.
We've just switched-out one set of factors for another.
hamster143
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#12
Dec7-09, 08:00 PM
P: 986
Competition for mates is everything, even with humans. Just because there are equal numbers of males and females, that doesn't mean everyone gets the mate they want or even necessarily mate at all! That's absurd.
There's no requirement for everyone to get the mate they want. There's still competition for mates, but it's just a game with no evolutionary consequences (and, sometimes, with perverse evolutionary consequences) - just because I don't get Chelsea Clinton or Beyonce Knowles, does not mean that my genes are worse off. It may mean that my genes are slightly better off, because the person I do end up marrying might give me 4 children, and that would've been less likely, had I been a "winner" of the game.

So then not all mate....so then evolution still matters....
The question then becomes, why do the remaining 5% fail to mate? Is it because of their genetic weaknesses, or some environmental reasons?

Assuming the former, here's a mathematical problem. Imagine two societies. In society A, the least adapted 5% fail to mate. In society B, the least adapted 50% of all children die before the age of 20. Compare rates of evolution in societies A and B.
The_Absolute
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#13
Dec9-09, 03:12 AM
P: 182
Poor, and uneducated people have many more children than wealthy, and educated people. Such as is often the case in third-world countries, especially in rural Africa. Thus, creating more poverty, starvation, disease, and crime.
BoomBoom
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#14
Dec9-09, 02:31 PM
P: 293
Quote Quote by The_Absolute View Post
... Thus, creating more poverty, starvation, disease, and crime.
I would contend that none of these things are genetic traits. ASAIK, there is no 'poor' gene.
xxChrisxx
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#15
Dec10-09, 09:10 AM
P: 2,032
Quote Quote by The_Absolute View Post
Poor, and uneducated people have many more children than wealthy, and educated people. Such as is often the case in third-world countries, especially in rural Africa. Thus, creating more poverty, starvation, disease, and crime.
This is again, criteria that YOU define as bad, and is therfore irrelevent to evolution.
Eddbio
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#16
Dec10-09, 02:00 PM
P: 10
The human population has increased massively in recent times and therefore so has the number of potential mutations. In addition we are living longer and having children at older ages. The older you get before having children the higher the chances of mutations occuring. The reduction in selection presures on humans has made evolution more random but not removed it. Variation amongst human beings may well be increasing.

There was a good case study involving the removal of a selection presure on a species of butterly but I am afraid I can't remember the name. The patterns on the butterfly wings increased until it was reapplied. Due to the removal of a predator I think.

You could consider the amount of chemical pollution in the environment increasing mutations? Or the masking of peoples smells/pheromones by using perfumes and deoderants, perhaps you might not be put off by your cousins smell untill it is too late. The effects of religion and culture on human mate choices. Do attractive people have less children and who has the most (hillbillies)?
Eddbio
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#17
Dec11-09, 01:15 PM
P: 10
The Fritillary butterfly I believe.
mgb_phys
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#18
Dec11-09, 01:51 PM
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Quote Quote by Eddbio View Post
The effects of religion and culture on human mate choices.
Ironic that a tenancy toward religion and having large families could be an evolutionary trait !


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