Is Evolution a "posthuman" concept?

[sfs]

So, would the black people who live in Norway fade their color gradually?
Or, the Norwegian people will gradually become light-gray in color?

If not, why not?

I'm not sure which imaginary scenario you're talking about now. Individual dark-skinned people living in Norway will have slightly lighter skin after a month or so, and then remain the same color. Assuming they are a small fraction of the population, their alleles conferring darker pigmentation would quickly (i.e. within a few thousand years) become dispersed throughout the population. If those alleles are still being selected against, they would also disappear completely pretty quickly; if not, most would eventually disappear by chance eventually anyway.

 

[sfs]

OK, let me see a little more according to your definition.

By your definition, then everyone is evolving everyday.

No. Every group is evolving every generation.

This definition can obviously not apply to fossil record. If so, what word could paleontologists use to define their idea of evolution?

The fossil record does not evolve. It is a record of organisms that did evolve. And yes, the same definition applies to paleontologists. Just because they can't detect evolution between two sets of fossils doesn't mean it didn't occur.

Why would such a definition have any practical meaning to both biology and paleontology?

Because genetic change over time is a fundamental fact about all populations of organisms (which obviously makes it of interest to biologists), and it is the process by which all diversity of life originates. Kind of important.

We recognize that genetic change happened all the time. This fact could simply be put as a background knowledge.

This is among the crazier objections I've seen to evolutionary biology. Yes, we recognize that genetic change happens all the time. In many cases, that changes produces visible changes in populations. The fact that populations change, and that the fact that those changes are responsible for the diversity of life on earth, were recognized before anything was known about genetics, and some name had to be given to the process of change. The name chosen was "evolution", a perfectly reasonable word since it just means, more or less, "change".

Why do we need to waste this word, which could be put to a much better use, to define the background process?

Perhaps I haven't been following the news closely enough -- has there been a shortage of words lately? "Evolution" is a useful word for biologists, some of whom spend all of their time studying how, why, how fast, etc evolution occurs. If they want to talk specifically about the formation of new species, they use a different word, "speciation", which again seems like an appropriate choice. If they want to talk about some other detailed aspect, they'll use a different word or phrase.

What is the point of any of this?

 

[juvenissun]

No. Every group is evolving every generation.


The fossil record does not evolve. It is a record of organisms that did evolve. And yes, the same definition applies to paleontologists. Just because they can't detect evolution between two sets of fossils doesn't mean it didn't occur.


Because genetic change over time is a fundamental fact about all populations of organisms (which obviously makes it of interest to biologists), and it is the process by which all diversity of life originates. Kind of important.


This is among the crazier objections I've seen to evolutionary biology. Yes, we recognize that genetic change happens all the time. In many cases, that changes produces visible changes in populations. The fact that populations change, and that the fact that those changes are responsible for the diversity of life on earth, were recognized before anything was known about genetics, and some name had to be given to the process of change. The name chosen was "evolution", a perfectly reasonable word since it just means, more or less, "change".


Perhaps I haven't been following the news closely enough -- has there been a shortage of words lately? "Evolution" is a useful word for biologists, some of whom spend all of their time studying how, why, how fast, etc evolution occurs. If they want to talk specifically about the formation of new species, they use a different word, "speciation", which again seems like an appropriate choice. If they want to talk about some other detailed aspect, they'll use a different word or phrase.

What is the point of any of this?

The point is simple: Your definition of evolution only applies to samples that their genetics can be studied. To those samples that could not be studied on genetics, this definition should not be applied and could only be treated as an assumption. Since 99% (?) of species ever existed could not be studied on their genetics, so your definition can only be used in a very limited sense.

And, furthermore, to those 1% sample that could be studied on genetics, this definition is not useful either. My son's genetic information is different from mine, so he is evolved. But for a foreseeable generations in the future, I do not expect to see a chance that my grand grand .... son will become another human species. If so, why should I care about this definition?

 

[juvenissun]

No, you were told by sfs that complete isolation of modern human groups for very long periods of time was and is very difficult. You were also told by sfs that genetic differences between modern human populations were indeed the result of isolation, specifically isolation by distance. See post #86 in this thread (the first time "isolation" was introduced in this thread.)

So, I assume that some groups of early human were isolated for a while and is identified as a different human species.

Then the isolation was bleached, then interbreed took place, and the characteristics of that human species then disappeared.

Is that what human evolution is about?
Could we also predict that 100,000 years later, all humans will merge into one color?

 

[The Engineer]

The point is simple: Your definition of evolution only applies to samples that their genetics can be studied. To those samples that could not be studied on genetics, this definition should not be applied and could only be treated as an assumption. Since 99% (?) of species ever existed could not be studied on their genetics, so your definition can only be used in a very limited sense.

You got sfs completely wrong. He did not give you a definition of evolution, he gave you evidence for it. At no point did he say that evolution is only proven by genetics.

And, furthermore, to those 1% sample that could be studied on genetics, this definition is not useful either.

Again, sfs didn't even give you a definition, if I understood him correctly. So stop talking about 'his' definition.

My son's genetic information is different from mine, so he is evolved. But for a foreseeable generations in the future, I do not expect to see a chance that my grand grand .... son will become another human species. If so, why should I care about this definition?

Is it just me, or does this boil down to evolution is wrong, therefore evolution is wrong?

 

[sfs]

The point is simple: Your definition of evolution only applies to samples that their genetics can be studied. To those samples that could not be studied on genetics, this definition should not be applied and could only be treated as an assumption. Since 99% (?) of species ever existed could not be studied on their genetics, so your definition can only be used in a very limited sense.

It's not my definition; it's the definition used throughout biology. If you don't like it . . . well, too bad. It's a useful definition because it separates one class of change, those caused by changes to DNA, from others, like changes caused by better nutrition. Thus, changes to human skin color over thousands of years reflect evolution, while changes U.S. height over the last century don't (instead reflecting mostly better nutrition).

At the finest resolution, you can indeed not always tell from fossils whether differences are the result of evolution; it's impossible to say whether two specimens of Homo erectus differ because the population had evolved between the times they lived, or whether they represent normal variation within the population. That doesn't represent a failing of the definition; it just demonstrates that fossil evidence is limited in what it can tell us about evolution. Changing the name that is applied to the changes involved would have zero effect on what we actually know, and it continues to baffle me why you think this is worth arguing about.

In any case, on a broader scale, such concerns don't exist. You don't need to study the genetics of H. erectus to know that they're genetically different from chimpanzees, or from lemurs or from bananas.

And, furthermore, to those 1% sample that could be studied on genetics, this definition is not useful either. My son's genetic information is different from mine, so he is evolved.

Neither you nor your son is a population. It's populations that evolve, not individuals.

But for a foreseeable generations in the future, I do not expect to see a chance that my grand grand .... son will become another human species. If so, why should I care about this definition?

I can't think of any reason at all why you should care about this definition. And yet you do; in fact, you seem to care a great deal about it.

 

[sfs]

You got sfs completely wrong. He did not give you a definition of evolution, he gave you evidence for it. At no point did he say that evolution is only proven by genetics.

No, but I did say that evolution always involves genetic change, by definition.

 

[sfs]

So, I assume that some groups of early human were isolated for a while and is identified as a different human species.

Then the isolation was bleached, then interbreed took place, and the characteristics of that human species then disappeared.

Is that what human evolution is about?

Assuming I understand you, then yes, that is one small piece of the story of human evolution.

Could we also predict that 100,000 years later, all humans will merge into one color?

Unlikely, unless the selective pressures for dark skin in the tropics and light skin in the high latitudes are removed.

 

[RickG]

I haven't seen that use of "clade", which is inconsistent with normal phylogenetic usage. A clade consists of all organisms descended from single group (usually a species, but it could be as small as an individual). As has been pointed out several times in this thread, there is usually at least some interbreeding between groups in humans, meaning that any clade large enough to encompass a good-sized group woud have to include virtually the entire human population.

The term common used in genetics is "population", which has the advantage of being vaguely defined and implying no particular boundaries, kind of like the groups it describes.

Thanks for the info. Like I said, not my area, but always glad to learn.

 

[juvenissun]

It's not my definition; it's the definition used throughout biology. If you don't like it . . . well, too bad. It's a useful definition because it separates one class of change, those caused by changes to DNA, from others, like changes caused by better nutrition. Thus, changes to human skin color over thousands of years reflect evolution, while changes U.S. height over the last century don't (instead reflecting mostly better nutrition).

At the finest resolution, you can indeed not always tell from fossils whether differences are the result of evolution; it's impossible to say whether two specimens of Homo erectus differ because the population had evolved between the times they lived, or whether they represent normal variation within the population. That doesn't represent a failing of the definition; it just demonstrates that fossil evidence is limited in what it can tell us about evolution. Changing the name that is applied to the changes involved would have zero effect on what we actually know, and it continues to baffle me why you think this is worth arguing about.

In any case, on a broader scale, such concerns don't exist. You don't need to study the genetics of H. erectus to know that they're genetically different from chimpanzees, or from lemurs or from bananas.


Neither you nor your son is a population. It's populations that evolve, not individuals.


I can't think of any reason at all why you should care about this definition. And yet you do; in fact, you seem to care a great deal about it.

Yes. So, The definition of evolution you used (i.e. your definition) does not apply to fossil study. And I assume early human species should be treated as fossils.

Why do I care? Because I have a few paleontologists in my department and I have never heard that they use genetics as an argument in any of their studies. If so, why do we need this (your) definition when we look at human evolution? Why don't we just use speciation as the minimum requirement for a meaningful evolution process?

The genetic changes on human do not lead to speciation. So, human does not evolve.

 

[juvenissun]

Assuming I understand you, then yes, that is one small piece of the story of human evolution.


Unlikely, unless the selective pressures for dark skin in the tropics and light skin in the high latitudes are removed.

Hey, common, why should this factor jump out? I thought interbreed is the main factor. Now every race breed with every other races at a rate fast then ever, so why not a big homogenization in a long run?

 

[Gottservant]

Thanks, guys.

I thought that compliment was lost for good, but you handed it back to me.

 

[juvenissun]

Thanks, guys.

I thought that compliment was lost for good, but you handed it back to me.

In fact, I like this thread. I think most discussions took place actually addressed the key point of your OP.

 

[Loudmouth]

The genetic changes on human do not lead to speciation. So, human does not evolve.

False. Humans are not speciating. However, they are evolving. You don't need speciation in order for evolution to occur. Speciation is simply two lineages evolving on divergent paths.

For example, human hemoglobin is evolving a great deal due to the selective pressure of malaria. Evolution does not stop, and it does not wait for a speciation event. The only way evolution would not occur is if there were an unlimited supply of food and no one died. Last I checked, people still starve and die. Evolution is still occuring in the human population.

 

[sfs]

Hey, common, why should this factor jump out? I thought interbreed is the main factor. Now every race breed with every other races at a rate fast then ever, so why not a big homogenization in a long run?

Interbreeding keeps populations from diverging too much due to random drift. Strong selection, however, can still keep certain traits distinct in different populations. It depends on how strong the selection is and how much interbreeding there is.

 

[juvenissun]

Interbreeding keeps populations from diverging too much due to random drift. Strong selection, however, can still keep certain traits distinct in different populations. It depends on how strong the selection is and how much interbreeding there is.

So, is the environment for Eskimos strong enough? If not, what would be an example of a strong force of selection?

 

[juvenissun]

False. Humans are not speciating. However, they are evolving. You don't need speciation in order for evolution to occur. Speciation is simply two lineages evolving on divergent paths.

For example, human hemoglobin is evolving a great deal due to the selective pressure of malaria. Evolution does not stop, and it does not wait for a speciation event. The only way evolution would not occur is if there were an unlimited supply of food and no one died. Last I checked, people still starve and die. Evolution is still occuring in the human population.

This is interesting. I can see the abundant food will avoid competition. And that is almost a negligible condition for humans today.

Why would no death prevent (your) evolution? I thought it should be no birth. Did you make a mistake? Even no death and no birth, according to your idea, evolution will still happen. We are almost a different person every 7 years. Aren't we?

 

[sfs]

So, is the environment for Eskimos strong enough?

I don't know. No one knows.

If not, what would be an example of a strong force of selection?

At the moment, effective resistance to HIV/AIDS in southern Africa.

 

[juvenissun]

I don't know. No one knows.

At the moment, effective resistance to HIV/AIDS in southern Africa.

So this force of selection is even stronger than interbreed? How does it work? Would all humans become resistant to HIV eventually? Or those who are resistant now would become MORE different than the rest of us regardless of interbreed?