Thursday, July 19, 2007

Skulls Add to "Out of Africa" Theory of Human Origins

It has been puzzling the international scientific community for quite a while now, did the early humanities interbreed or not? If you think of it, we do know that we share with chimpanzees more than 95% of our genome, right? And the two groups (humans and chimpanzees) were separated definitely some 4.5 million years ago (if I am not mistaking with the number), right? So maybe just MAYBE early Homo sapiens and early Homo neandertalensis interbreed, or maybe Homo sapiens and other human forms, who knows.

The question is not only a poetic one, thinking about early romances across the borders of tribal wars and what ever some poets might imagine. No the question is deeper, or at least more troubling for some, more interesting for others. It's orbits mainly 2 points:

  • A strictly scientific question:

    Let's remember the definition of species:
    1. Wordnet: taxonomic group whose members can interbreed

    2. Wikipedia: In biology, a species is, loosely speaking, a group of related organisms that share a more or less distinctive form and are capable of interbreeding.


    You can search more definitions, you know the procedures type "define:species" and you'll get a myriad of definitions, however an important detail will certainly repeat itself in all definitions: Interbreed, Interbreeding. Fore this is an important detail about naming species, two ordinary individuals that are grouped in one species need to be able to interbreed in order to belong to the same species. However, some scientists tend to put the modern human and the Neandertal human in one species: Homo sapiens. In that perspective, the modern human would be Homo sapiens sapiens and the Neandertal human would be Homo sapiens neandertalensis. Could that be true?

    We certainly have no way to reach a sexually functional Neandertal in order to try and make it fuck a human and then see if they give a healthy, fertile offspring (keep in mind that many animals belonging to two different species may breed but their offspring is sterile there fore the process is scientifically a failure). But modern day scientists don't always refer to actual interbreeding to define species, they use molecular biology and genetic studies of the genome and so on. But even that is useless as the sample of Neandertals are rare (same as any ancient human remains) and when we do find some remains, it's usually bones, and even when we do find remains of soft tissues it's usually mineralized tissues and not mummified tissues... In other words we have no material to extract DNA from, some studies did find a few fragments of DNA but that hasn't been able to clear the question of whether neandertals and modern humans belong to the same species or not.

    But many scientists already speak of Homo sapiens neanderalensis... Which brings us to another point that is less scientific, but more philosophical and existential...



  • What is a Human?

    Of course, if you do sink deep into Paleoanthropology and evolution in general, humanity will lose its spark and it will make Man the special creature of God... it will make him just another animal. I don't know whether it's insulting or relieving to acknowledge that but for most people it's simply disturbing! But so far we did preserve a small shred of superiority: We, the Homo sapiens, have ruled the world with our wit and intelligence.

    But what if We didn't rule it? What if other humans have ruled it with us? What if we were not pure Homo sapiens what if we were a mix of humans and that other humans rule the earth together with the combination of all our genes. Of course some might argue that we don't look like neandertals or like Homo ergaster or any other humans. But the truth is that Phenotypes (looks) are deceiving we can hold more DNA from Neandertals than we do from Homo sapiens and still look like the latter. Because different pieces of DNA fulfill different roles. If that is true then we would have nothing, and I mean, NOTHING, that sets us apart from other animals.

    I know many of those who follow my blog may not find this so shocking or so disturbing. But come on people we might not be the world's number 1 believers, but many people around the earth are strong believers and many of them believe that God created all animals in one day and MAN on a totally other day. Many people justify their right to kill animals because they are...animals... not Humans...not special enough.


I have been trying to follow the news of this subject for nearly 2 years now, reading every article about it. And finally I have found a study that claims to have some rational answer to that question. You can read it in the Scientific American Online edition.

The article focuses on the fact that humans did in fact expand to the world starting from Ethiopia (Africa), which is no longer seriously questioned by scientists. In proving their point they rely on the decline of variability in skull structure from the cradle of modern humanity (Ethiopia) to the farthest regions (Asia for example). However here's the piece that interests us:

As smaller bands broke off from larger settlements, they would have carried with them a less diverse subset of the bigger group's genes, which partly translate into anatomical features such as skull shape. So the farther early Homo sapiens trod from their homeland, the less variable their skulls should become. Unless, that is, they bred with previously established populations of Neandertal or other early humans, which would have injected new genes and boosted variability.

The researchers found no signs of interbreeding, they report online today in Nature. "What you find is a very nice linear decline of variability as you move farther away from Africa," Amos says. Prior studies had identified an identical trend in the diversity of simple genetic sequences or markers.


So maybe religious lunatics can sleep well tonight... We didn't interbreed with Neadertals. But that leaves an important question yet unanswered:

Was it biologically impossible for us to interbreed?

Just because we didn't interbreed with them doesn't mean it would have been impossible. One thing is certain, we had all the chances to do so. The variation of weather over the last 100 000 years (modern Man's appearance is estimated to around 120 000 years) have defined many regions of crossing at least between modern man and Neadertals. The most important region being the Middle East in which I live. Unfortunately, studies in here are rare, the only place where serious scientific research takes place is Israel (the only place where an abundance of remains was found, though Lebanon for example contains many caves, thus must've had many remains).

On the other hand, knowing of how humans are xenophobic by nature (check out this article in National geographic news). You can't help but to think to yourself: Both groups must've forbidden such contact between different members, probably declaring it a sin or something and promoting the others' mass murder.

I strongly believe that

49 comments:

NOMAD said...

here, is a good article about the differentiation of the 2 humanoïd species

how did they hunt

here another article which corroborates what you were supposing

skull of a young boy

well, I tend to think, as my first link says, that neandertals and our ancestors could not interbreed

Severian said...

When Neanderthal's were first discovered they were considered a different species. Then more enlightened scientists took over and said Neanderthals were a variation of human and we are all one big happy family. But recent (5 years ago?) fragmentary DNA analysis suggested Neanderthals are a separate species afterall. Who knows for sure.

They could surely engage in intercourse. What I wouldn't give for some hot muscular Neanderthal cavewoman butt ;-). But could they have viable offspring?

Despite having 98% the same DNA as chimps, we can't have viable offspring with them because they have a different # of chromosomes. But surely Homo sapiens and neanderthalensis have the same number of chromosomes and even more shared DNA than with apes. Are horses and donkeys more closely related than humans and Neanderthals? I'm guessing not. I'm also guessing babies could be produced but I'm not sure if they'd be viable or sterile like a mule (=horse+donkey).

Some think that the prevalence of pixie, giants, leprechauns, trolls etc. in our mythologies reflect our distant past when we were co-existing with other sorts of hominids, bigger and smaller and strangely shaped. I think that is a very interesting idea.

programmer craig said...

I've always thought the ability to freely interbreed (means produce viable offspring) was the minimum requirement of the "species test".

Dogs and wolves can freely interbreed, for instance, yet are considered tow different species. This is almost assuredly a distinction we humans have made to separate our beloved pets from dangerous predatory w9ld animals, because I don't think it would be scientifically sound to suggest that dogs and wolves are not the same species. Dogs are just a product of many generations of selective breeding of wolves. Everyone acknowledges that, because it's too obvious to deny. But we still classify them as being different.

The "species test" can get very complicated. For instance, theer are documented cases where isolated pockets of animal populations have begun evolving along different lines, and the populations that were adjacent to each other could all freely interbreed, all across the geographical area. But the populations furthest apart from each other could not freely interbreed. Is that a "pass" or a "fail" on the species test?

I don't know if humans could interbreed with neanderthals or not. But even if they could, I'd be highly suspicious of anybody who claimed Neanderthals and Human beings were one and the same. Humanity was clearly on the evolutionary path to speciation (just as in that example I listed earlier) prior to our development of civilization. I'm certain that if we had continued to exist in a primitive state, there would be at least several species of us, by now. It's happened with many other animals, and it would have happened to us as well. The evidence of that is in the way widely dispersed populations developed wildly different genetic traits. But that's not a politically correct thing to say, so nobody says it. I think it is also politically correct to say that Neanderthals and Humans had only minor differences, despite quite obvious physical dissimilarities and an abundance of scientific evidence to the contrary. I wish our sensibilities as people didn't play a role in scientific research, but they do :)

NOMAD said...

as you have a scientist background, may-be those links will find your interest (a bit tecnichal for me)

neandertal genome ?

a paleonthropologist's blog

Severian said...

aka: Liev/Severian/Bsharp. This site keeps giving me different names.

Anyway, Programmer Craig an insightful post. I don't think you should put so much stock in the "non-interbreeding" definition of species. That definition works for most established, sexually reproducing species in the world. But, obviously that definition breaks down when describing asexual species and it also breaks down in describing species which are undergoing rapid evolution. Your examples, dogs and humans are surely examples of this.

You note that dogs and wolves can interbreed sometimes but are considered different species. Note also that certain dog strains, say a chihuahua and a Great Dane, are considered the same species but can't interbreed because their sizes don't allow intercourse. The species definition doesn't apply well. Surely the same is true for humans.

The point being, that transitional species have transitional barriers to interbreeding including (as you allude to) geography, (as Pazuzu mentions) social barriers and other factors (human intervention).

Humans have clearly evolved rapidly in the past 1 million years. Only Homo sapiens sapiens remains but, on the basis of fossil bone scraps, are we really ready to claim that H.sapiens and H.neanderthalensis were more different than dogs and wolves are?

If, as Pazuzu suggests, there were social taboos separating H.sap and neanderthals, we can be confident in human nature that there were some taboo breakers. So I think the safest guess as to whether they interbred would be "sometimes" as would be true for any transitional, rapidly evolving species. Groups of "pure" neanderthals may have died out but I think their genes remain with us.

p.s. a built in bias exists because there is more money and fame involved in discovering a new species of human than a new species of insect or frog.

programmer craig said...

Interesting take on things, liev. I would disqualify dogs and humans from consideration as examples though, because in both cases natural evolution no longer applies, and hasn't for about ~10000 years. In the case of dogs, it's because they are a product of deliberate selective breeding, which isn't natural. And in the case of humans, it is because we removed ourselves from the natural order when we developed civilization. There isn't any environmental "survival of the fittest" that applies to either, in my opinion. Humanity is rife with genetic traits that would have made survival extremely problematic in a natural environment. A very high percentage of us have poor eyesight, for instance.

Severian said...

Programmer Craig, I understand your objection. Many feel the same way about human evolution and "survival of the fittest" but I think there is a more clear and germane way to view the issue.

First some definitions: evolution is (formally)a change in gene frequency of a population or (informally) a change in the structure or chemistry of an organism. Evolution (and speciation) has occurred mostly through natural selection but also through other forces such as mutation, isolation and artificial selection.

We think of natural selection as occurring due to the natural environment, weather, geography etc. Most are aware that the biological environment is also important, notably food supply and predators. But the social environment can be just as important in driving selection and evolution.

Consider the ultimate in symbiotic relationships, the lichen, in which an alga and a fungus have become so interdependent they function as one organism. The evolution of one is completely dependent on the evolution of another.

Humans and dogs are symbiotic (more so in the past) though surely humans have affected dog evolution more than vice versa. The selective breeding we humans do is called artificial selection and thus it is very easy to think of it as fake selection or fake evolution. But it is very real. Humans have become a nearly essential part of the dog's natural environment.

Humans are also symbiotic with each other. Very difficult for a human or even a few humans to survive completely on their own. Our social environment IS our environment and it clearly exerts a strong selective, evolutionary force on us.

You note that weak eyesight is a survival issue in a "natural" environment. But our natural environment is to live in a cooperative society where the sharp sighted help the weak sighted, the strong armed help the weak armed, the sharp minded help the weak minded, etc.

Consider that our social environment has selected for some pretty bizarre traits like ability in art, math, music even blog writing ;-). All these would be completely useless talents in the mythical "natural" setting where each person has to fend for themself.

Many think we "removed ourselves from the natural order when we developed civilization." but I disagree. As a species we are still struggling, like all creatures, to extract enough energy from our environment to survive, grow and reproduce. Its just that we do it together.

(and if you were thinking of using war as a counter-example to our cooperative social nature, well, that deserves a whole n'other post. But until then, consider why human population tends to have its highest growth and density in war torn areas)

programmer craig said...

Hi Liev,

Thanks for the long reply. I'm going to respond in sections, as I may not have time to answer the whole thing in one sitting :)

First some definitions: evolution is (formally)a change in gene frequency of a population or (informally) a change in the structure or chemistry of an organism.

I don't really agree with that. Do you mind me asking where that definition comes from? It's been a long time since I studied evolution, but I don't recall anything about "chemistry" being part of the theory. Is that a recent definition? Because it seems substantially less precise than what I learned.

Evolution (and speciation) has occurred mostly through natural selection but also through other forces such as mutation, isolation and artificial selection.

I think you're defining both parts of the mechanisms for evolution separately, when in fact evolution could not occur without both parts.

My understanding is that the DNA sometimes mutates as a result of cosmic radiation and other factors. This produces a new genetic trait in the organism. When the trait is desirable, the chances of the organism surviving to adulthood to reproduce and pass on the new trait are increased. When the trait is undesirable, the chances of surviving to pass on the trait are lower (or non-existent in the case of a lethal flaw) and therefore the new trait will be removed from the gene pool within a few generations, instead of increasing in frequency over time.

That's where "survival of the fittest" comes in. It is that which prevents all traits, both good and bad, from being passed on to subsequent generations. There could be no evolution without natural selection.

Isolation is not necessarily part of evolution. Populations will continue to evolve whether they are isolated or not. Isolation does eventually lead to speciation, though, as populations that are isolated from each other will drift further and further apart genetically until they are eventually no longer the same species.

Artificial selection is not (and can not be) considered to be an evolutionary process. At least, not in my opinion. Rather, it is the opposite of natural evolution. It's a human effort to select for traits that are "desirable" according to arbitrary standards. Beef cattle who are docile and muscular, for instance. Miniature dogs, with gentle temperament and good color. Etc...

I'm just going from memory, but I'm pretty sure I've got it right. I used to know a lot about this subject and I don't think I've forgotten all of it, yet :)

programmer craig said...

But the social environment can be just as important in driving selection and evolution.

Absolutely. Specimens who vary too much from the locally accepted "norm" (physically) will not be easily accepted as potential mates. That's a key element in the evolution of social animals.

Consider the ultimate in symbiotic relationships, the lichen, in which an alga and a fungus have become so interdependent they function as one organism. The evolution of one is completely dependent on the evolution of another.

Hmmmm.... that's a bit of a stretch, I think. They are dependent on each other for survival, but not evolution. Although, evolution is difficult without survival :)

Humans and dogs are symbiotic (more so in the past) though surely humans have affected dog evolution more than vice versa.

I don't think humans and dogs are "symbiotic" - dogs (or domesticated wolves, more accurately) were undoubtedly a great help to early man. But wolves survived just fine without humans around, and I don't have any reason to believe humans would have died out without pet wolves.

programmer craig said...

The selective breeding we humans do is called artificial selection and thus it is very easy to think of it as fake selection or fake evolution.

Actually, it is easy to consider it "fake" evolution, because that is exactly what it is. You can use the word "evolution" to describe selective breeding only if you use it in the most generic sense, to mean nothing more than a change.

Selective breeding has no place in evolutionary theory. It actually represents a defeat of natural evolution.

But it is very real. Humans have become a nearly essential part of the dog's natural environment.

Dog's don't have a natural environment. They have a man-made environment. As do humans, by the way.

If all dogs became feral, all of man's 10,000 years of selective breeding would be undone within about 100 years. Or less, given the dog's accelerated maturation - that could theoretically be 100 generations of canines.

And I suspect that dogs, after 100 years of living in the wild without human interference, would look quite a lot like their ancestors, the wolves. The vast majority of the recessive traits that humans have bred for, would vanish.

Humans are also symbiotic with each other. Very difficult for a human or even a few humans to survive completely on their own.

You could say the same for any social animal, including ants and bees! Only, much more so in the case of insects! :)

I'm not sure I see your point, though? Humans have always been social animals. Humans have not always been civilized. My argument is that it was civilization that removed humanity from the natural order.

Our social environment IS our environment and it clearly exerts a strong selective, evolutionary force on us.

Not any more, in my opinion. You might have been able to make that case up until about 200 years ago. Even then it would have been a stretch. But now? No way.

Not only do we allow "defective" specimens to survive, we encourage it, even at great expense. And we encourage them to find mates and have children. Likewise, we no longer allow people to perish when they can't provide for their own needs. And medical/scientific technologies allow people born with previously lethal genetic flaws to live relatively normal lives.

You note that weak eyesight is a survival issue in a "natural" environment. But our natural environment is to live in a cooperative society where the sharp sighted help the weak sighted, the strong armed help the weak armed, the sharp minded help the weak minded, etc.

So you are arguing that natural selection is still being done, but selection is by different factors?

I can't agree with that. There is no "survival of the fittest" for humanity, any more. We all survive. Worthy or not.

Consider that our social environment has selected for some pretty bizarre traits like ability in art, math, music even blog writing ;-).

I don't know about that. I've never been attracted to a woman only because she was an artist, musician, or writer! I will agree with you that I find intelligence attractive, but I'm guessing intelligence and creativity were both survival traits in the primitive environment as well. Man is not particularly large, strong, powerful, fast. We don't have large sharp teeth, and we don't have claws. We survive by our wits and by our creative problem solving.

All these would be completely useless talents in the mythical "natural" setting where each person has to fend for themself.

We (humans) never had to fend for ourselves. We've always been "group" critters :)

Many think we "removed ourselves from the natural order when we developed civilization." but I disagree.

I disagree with your disagreement! Or something :P

As a species we are still struggling, like all creatures, to extract enough energy from our environment to survive, grow and reproduce. Its just that we do it together.

Yes, but I humbly submit that is mere survival, not evolution.

It could be, though, that after humanity has bred all unique "ethnicity" out of the gene pool by inter-marrying for many generations and across all boundaries, we will have some idea of what our common ancestors actually looked like. Which should be pretty cool. I wish I'd be here to see it. In my opinion, mixed people are the best looking (and maybe the most intelligent too) - but only when they mix across type. Meaning, a big difference between the "type" of the two parents. Black and white for instance. The Europeans are too close, and mixing a slav with a german seems to produce children who are uglier than either parent, by a lot! Don't tell anyone I said that, though, because I'm sure the Europeans are quite happy with their politically correct potato headed-ness.

(and if you were thinking of using war as a counter-example to our cooperative social nature, well, that deserves a whole n'other post. But until then, consider why human population tends to have its highest growth and density in war torn areas)

Or, perhaps the areas with the biggest population problems are most likely to engage in warfare? Could be there is a natural explanation for war, but I wouldn't want to be the one trying to make it :)

Severian said...

Craig, wow, you did put a lot of thought into your responses and you are obviously well educated.

I must confess my definitions etc. originate from the main thrust of my education, which was evolutionary biology (general and human). I really find it fascinating and complex.

I'll try to address your points concisely (so as to not overly dominate this blog if we haven't already done so). I think I held most of your views myself at one time and I can remember how reluctantly I gave them up as my education progressed. So I don't expect full agreement, certainly not right away.

1. I should have been more stringent. Evolution can ONLY really be defined as a change in gene frequency in a population. An individual organism can't evolve. Changes in appearance are not evolution. If flamingoes stop eating mini-shrimp they stop being pink, if a fox population finds a new rich protein source they will grow bigger but if it disappears their offspring will be small again. Evolution need not require a change in appearance at all, as for changes in blood types, pheromones, enzymes etc. (the basis for the "chemical" issue you mentioned). Only "Changes in Gene Frequency" works as an airtight definition of evolution.

2. One of the most universal sources of misunderstanding evolution is the classic picture of a cell evolving to blob evolving to fish, to amphibian to reptile, to monkey to ape to caveman to modern human. It may roughly depict how WE got here but doesn't describe evolution as a whole. The worst parts of that picture is that it illustrates evolution as directional and it depicts humanity as the peak, the pinnacle of evolution.

I see this as a quasi- or fully religious view; an extension of the view that Man is God's Special Creation. If you take this view, that is fine, I won't debate but it puts a damper on a deeper understanding of evolution.

Evolution is not directional. There are no "desireable traits". Genes survive based on how well they allow an organism to survive and reproduce in a given environment. But all environments change, so what is successful at one time may not be later. The evolutionary record is not full of organisms striving for greater complexity or intelligence or whatever. There are many examples of evolution sideways or even toward simpler forms. Environmental changes can push population gene frequency in any direction. We humans just enjoy the increased complexity stories.

3. Examples of evolution without natural selection:
A. say there is a population of tortoises in a field with 33% black, 33% brown and 33% red shells. They all interbreed freely and survive equally. An earthquake makes a giant crack in the field and by chance, all the tortoises are on one side except a male and female red shell are isolated on the other side of the crack. Voila! evolution without natural selection; isolation only. One side of the crack will instantly have 100% red shell genes.

B. Consider blind cave fish. Fish that used to have working eyes but now only have fleshy lumps after living in lightless caves for a million years. Why? It doesn't hurt them to have working eyes in a dark cave, why did they lose them? Answer: because negative mutations have slowly accumulated in the eye genes through time. Voila! Evolution without natural selection; from mutation only. This illustrates that natural selection is not only an agent of change but also (perhaps mostly) an agent of maintenance (as long as the environment doesn't change).

4. You are right! Humans have always been social (and ape ancestors and probably mammalian ancestors also). And yes, bees and ants and termites are much more advanced in social evolution than humans, much more symbiotic and reliant on the hive/colony for survival. Heck 99% of a hive/colony can't even reproduce. So why is bee evolution natural but human evolution unnatural?

Oh shoot, out of time. I think I addressed most issues but missed a few. Perhaps in another post. Bye!!!!

programmer craig said...

Hey there, Severian/Liev

Craig, wow, you did put a lot of thought into your responses and you are obviously well educated.

It wouldn't be fair to you to let you believe I'm "well educated" :)

I'm a former Marine Corps infantryman with about 2 years of college. I learned about evolution by reading some of my Father's college textbooks when I was a teenager. Which was a long time ago... hence my fuzzy recollection and possibly outdated information.

I must confess my definitions etc. originate from the main thrust of my education, which was evolutionary biology (general and human).

You know a lot more about the subject than I do then, but I still reserve the right to disagree! I used to drive my professors nuts that way when I was working on a degree. Especially the computer science folks, since I was already a working professional C programmer while I was in their classes. They hated my guts, every last one of them! I got on well with the science profs, though.

I really find it fascinating and complex.

Me too. Evolution and Anthropology are two of my favorite subjects.

I'll try to address your points concisely (so as to not overly dominate this blog if we haven't already done so).

Well, I hope Pazuzu won't mind. I'm enjoying the non-political debate, it's a nice change for me on blogs :)

I think I held most of your views myself at one time and I can remember how reluctantly I gave them up as my education progressed. So I don't expect full agreement, certainly not right away.

I may never agree. I don't agree with Anthropologists who place a high importance on the spread of language. Language was never more than an incidental factor in the Anthropology books I read. Now it seems to be of preeminent importance to many of them. Which, I find to be very illogical. I'm a logical person, that's why I enjoy computer programming so much. I require a logical explanation (one that makes sense to me) before I will accept new theories and ways of thinking. Particularly now. It seems that beginning in the 1980s, political correctness has run amok in many fields of scientific study.

OK, new comment for your bullet points :)

programmer craig said...

I have no disagreement with your #1 except for this part:

as for changes in blood types, pheromones, enzymes etc. (the basis for the "chemical" issue you mentioned).

All those changes are genetic though, correct? So I still don't understand why chemical composition was introduced into the mix?
On #2 I only disagree here:

The worst parts of that picture is that it illustrates evolution as directional...

Evolution is directional, in my opinion. Evolution proceeds towards the direction of maximizes the survival potential of an organism.

De-evolution would be evolution that proceeded in the opposite direction - reducing survival potential. I believe humans are de-evolving. If my whole neighborhood here in southern California was transported naked to a time 10000 years ago, would we fare better or worse than humans of that time period did?

I could make an argument we might do better because we already know how to do many things that humans couldn't do, back then. We could make tools, weapons, etc that they couldn't make.

I could make a counter argument that we don't know how to live in the wild the way primitive man could. We don't know how to hunt with spears. We don't know how to forage for edible plants. We don't know how to fish without modern fishing tackle. We don't know how to make rope and string from animal sinews. And so on.

But neither of those arguments is an evolutionary argument. On evolutionary grounds...

Many of the people in my neighborhood would die without medications. High blood pressure. Heart disease. Hyper-tension. Mental illness. Diabetes. Etc.

Many others would die due to bad eyesight. Me among them. I couldn't hunt without contact lenses or glasses. I couldn't even forage. I couldn't fight for a mate. I couldn't protect my family. Possibly, people would care for me as an invalid. But what are the odds of me being able to find a mate and reproduce?

And how about temperament? Courage is required in a primitive environment. How many of my neighbors have the necessary courage to engage in a fight to the death, with bare hands or primitive weapons? How many have the courage to face a grizzly bear or a mountain lion, with nothing but a wooden spear? Also, a lot of my neighbors are pretty hot headed and easily irked. I have an idea that might tend to get people popped over the head with a club a lot, in a primitive environment. I don't know how much of a factor temperament is in survival, but I think since humans haven't selected fro temperament for thousands of years, that it might be a problem.

I know you will argue that humans are evolving to suit their current environment, but I don't agree. Unless you can give me some examples of that? I mean actual changes to our DNA that help us survive in the modern (civilized) world. You might be able to persuade me on this one. I just see a lot of evidence of faulty genetics passed from generation to generation, and I don't see any evidence of improved genetic traits.

I see this as a quasi- or fully religious view; an extension of the view that Man is God's Special Creation. If you take this view, that is fine, I won't debate but it puts a damper on a deeper understanding of evolution.

I don't take that view :)

I'm only discussing humanity with you because it was one of the two examples I used earlier for species that are (in my opinion) existing outside of the natural order.

Evolution is not directional. There are no "desireable traits". Genes survive based on how well they allow an organism to survive and reproduce in a given environment.

Genetics proceed towards survival. That's a ----> direction. Also, traits that enhance survivability have to be called desirable, no?

I think on this one we are in agreement, but arguing semantically :)

I'll try to wrap up in one more comment...

programmer craig said...

But all environments change, so what is successful at one time may not be later.

Yep. And organisms that don't adapt (evolve) rapidly enough to a change in environment, become extinct.

As the Neanderthals did. (that was my attempt to get back on topic!)

The evolutionary record is not full of organisms striving for greater complexity or intelligence or whatever.

No, it's not. Organisms that are very successful (and don't face much threat) don't really need to evolve, regardless of how simple or complex they are.

Environmental changes can push population gene frequency in any direction. We humans just enjoy the increased complexity stories.

Yes, we do. We also enjoy the stories where all early hominids were pretty much the same. (another attempt to get back on topic!)

OK, #3

A. say there is a population of tortoises in a field with 33% black, 33% brown and 33% red shells. They all interbreed freely and survive equally. An earthquake makes a giant crack in the field and by chance, all the tortoises are on one side except a male and female red shell are isolated on the other side of the crack. Voila! evolution without natural selection; isolation only.

That doesn't really work, you know :P

You could make the opposite argument... that the turtles had evolved with different colored shells in isolation, but then natural barriers came down and they interbred freely, resulting in a complete and nearly random distribution of shell colors. Is that evolution too?

If that's the argument you make, then I would say that we can take somebody with blue eyes (like me) and pass a law that I can only have children with women who have blue eyes too, which would yield 100% instance of blue eyes in our offspring, and... Voila! Evolution by act of congress, right?

That's exactly what Hitler was proposing with his theories on racial hygiene and selective breeding.

So, we are back to whether or not selective breeding is evolution or not, aren't we?

Or if the opposite (interbreeding without the influences of natural selection) is in fact, evolution or de-evolution.

B. Consider blind cave fish...

I have two complaints about this example!

a) It's possible that the trait for eyes is not a selection factor in fish that live in complete darkness, but natural selection still occurs with other traits. The fish most easily able to detect vibrations in water, perhaps. I have no idea. But it seems there must be some selectors at work.

b) It's possible that eyes on a fish that lives in complete darkness adversely effect survival. It seems that having sensory organs that are designed to receive and process information would go a bit haywire when they never receive any data, no? Maybe it drives the little buggers insane? Crazy fish syndrome? Beating their little heads against the cave walls? But on the other hand, maybe they don't miss eyesight, when they don't have eyes?

We'd need to do a study on fish that were exactly the same in all regards except for eyesight, in the same environment, to be able to determine what evolutionary factors were at work on them.

#4

So why is bee evolution natural but human evolution unnatural?

Because humans don't live in a natural environment. How can there be natural selection in humans, when we protect ourselves from being adversely effected by nature?

This is another issue that just doesn't seem to pass the "is it logical" test, for me.

Oh shoot, out of time. I think I addressed most issues but missed a few. Perhaps in another post. Bye!!!!

OK, take your time. And feel free to only address whatever interests you. I know I type a lot, don't feel you need to answer everything :)

programmer craig said...

I forgot one thing, sorry!

Changes in appearance are not evolution. If flamingoes stop eating mini-shrimp they stop being pink

I assume you meant "changes in appearance are not necessarily evolution"?

Because I'd argue that most changes in appearance are genetic, not environmental, and are therefore caused by evolutionary factors.

if a fox population finds a new rich protein source they will grow bigger but if it disappears their offspring will be small again.

I know that is a popular argument, but I dispute it. I don't think diet effects factors such as height and muscle mass as much as we like to think.

For example, I raised two German Shepherd Dogs from puppies about 10 years ago. Both ate the same food, got the same amount of exercise... everything about their environment was the same. They came from different lineage and different breeders. One was heavy boned and had huge paws and a head like a basketball, even as a pup. He grew to be 28" at the shoulder and weighed 128 pounds, and he was strong as a bull. The other was fine boned and lean as a pup, and grew to only 25" at the shoulder and weighed about 80 pounds. Their temperament was also wildly different... luckily the large one was gentle as a lamb, but the smaller one was jittery enough that I got nervous whenever there were strangers in the house.

I can't really explain that except by genetics.

Another example is humans (me using the humans and dogs examples to death, aren't I?) - I frequently hear that East Asians (for instance) are larger in the US than in Asia because their diet is richer in protein. My ex-wife is Chinese and she's 5'3". Which is a little taller than most of her Chinese female friends. I've traveled to may parts of Asia and I haven't observed a difference in height there, or here. Japanese are short. Filipinos are short, but a little taller than Japanese. Koreans can be quite tall. So can northern Chinese. Southern Chinese are probably about average height for East Asians. And in all cases I think it'd be a tough argument to make that they are taller in the West than in Asia. I don't think their small stature is a product of their diet at all.

Another example using myself and my family. The Roman historians of 2000 years ago documented males from Northern Germany to be about 6' in height and about 200 pounds, on average. I'm 5'11" tall. I just weighed myself at the gym a few days ago, and I weigh 203 pounds. My father is 6'3" tall. My brother is 6'5" tall. My grandfather on that side was 6'2" tall. My uncle on that side is 6'1" tall. All of the men on my dad's side of the family are over 6' tall, except me. All of the men on my Mom's side of the family are just under 6' tall, same as I am.

In my family, the average height for males of our ethnicity is exactly what it was 2000 years ago.

However, the Romans 2000 years ago were small enough that they described 6' tall Germans as giants. The Italians of today are quite a lot larger than the Romans of 2000 years ago. Why? Diet? Evolution?

Neither, I think. I suspect the answer to that question lies in the Lombardi, the Burgundi, the Roxolani and the Normans who "invaded" Italy and Sicily and settled there, mixing with the populations over time.

OK, sorry for the foray into Anthropology, but I think it does have a bearing on the topic :)

NOMAD said...

being a star in deep oceans makes wonder why humans are so sure of their superiority

Severian said...

"being a star in deep oceans makes wonder why humans are so sure of their superiority"

Nomad I agree.

A thought provoking question in evolutionary biology is, "which is smarter a dog or a rat"? I think most would say dog but rats are far better at solving mazes than dogs. In fact rats solve mazes more quickly than most humans. How can that be? Aren't humans smarter than rats?

The best answer is to say that rats and dogs and humans each have brains evolved to solve different problems in life. Comparing intelligence across species is misguided. We say dolphins and chimps are the smartest animals but what we are really saying is they have brains and problem solving skills most similar to our own.

Perhaps it is similarly misguided to always try to compare the intelligence of humans to each other, figure out who is smartest. Perhaps each human brain has unique problem solving abilities (as we might see when a literature professor tries to fix a car).

NOMAD said...

(as we might see when a literature professor tries to fix a car).

:lol:

I wouldn't bet on a car either for different reasons : bad driver, bad hand-worker, doesn't care much for its performances or looks... but for its harmful effect in the atmosphere :lol:

Severian said...

Craig, I'll do my best. My point about biochemical evolution is that most people think of evolution as being a physical shape change because that's what we can see in the fossil record. Chemical changes are very important but we can't see them fossilized.

Anyway, will again try to define the most crucial components of evolution: only populations can evolve, not individual organisms and it defined as a sustained change in gene frequency.

Geographic catastrophes can make evolution happen instantly. The red shell tortoise example meant to show how a 33% red gene population can suddenly give rise to a 100% red gene population. Of course in nature such extreme examples rarely happen. And yes, previously isolated populations suddenly mixing is also evolution if gene frequencies change. There is no such thing as "de-evolution". A population's gene frequency will continue tochange based on prevailing conditions. It can't go "backward".

Artificial selection can make evolution (change in gene frequency) happen relatively fast. But in 10,000 years of domesticating plants and animals, humans really haven't changed the genetic makeup of our pets (is wheat a pet? :) very much from their wild forebears (as your dog=wolf example shows). Genetic engineering adds a new wrinkle but not as drastic as some fear.

Natural selection takes a much longer time to have a significant effect than artificial. As a convenience, lets say the average amount of time for a population to split off and evolve into a new species is 1 million years (is probably more).

You have trouble accepting this, but humans are not a product of artificial selection. Unlike cats and corn and canaries we generally choose our own breeding partners just like every other sexual species on earth. There is no overlord intelligence allowing some of us to breed and some of us to not breed. There is no giant farmer trying to make us bigger or smaller or more colorful or more nutritious.

Humans have only been "civilized" for about 8000 years. That isn't a long enough time for significant evolution. We'd need 992,000 more years to become a new "civilized man" species. We have to accept that human gene frequency is roughly the same now as it was at "dawn of civilization". That sounds so ancient but in evolutionary terms it is an eyeblink.

I think we can agree that your time travel argument mostly involves learned adaptations not genetic. So, some clever modern humans could learn to survive (and reproduce!)if transported 10,000 years back and some clever ancient people could learn to succeed here(see Geico commercial cavemen ;). But most of us are trapped in a living mode based on our childhood experience.

You hit the nail on the head with your response to the blind fish example. There are multiple factors being naturally selected for at all times. A near-sighted person in the past might have a disadvantage but could easily survive and REPRODUCE.

Reproduction is the key. That is all that really matters. You seem too wrapped up in this "brave caveman killing wild beasts" image. Ever consider that the weak eyed, slow footed guy who stays in the village with the women might end up produing more offspring than the mighty hunter? The evidence for that is right here! Unless you think all modern nearsighted people are a result of recent mutations, it is clear that in the past they survived and passed on their near-sighted genes.

There are similar "imperfections" in members of all species on earth social and non-social, seals and starfish!. And sometimes, when the environment changes, an imperfection becomes a strength.

Important to keep in mind that each individual organism is in greatest competition with members of its own species. Even when organisms get in groups (like a hive or army) the main purpose for the group is competing against similar groups. Thus the main purpose of war is actually increasing human population not decreasing it.

So I say don't worry so much about civilized humanity! I am confident we have the genetic diversity to survive as a species no matter how the environment may change (short of global meltdown but maybe even then...)

Severian said...

Craig, oops, I have to add two more things then I'll be done, (I swear Pazuzu!).

First regarding your disbelief in the idea that changes in diet can create large changes in an organism's appearance: The thing is, to rely on observations of your own family and pets to arrive at global conclusions for every form of life on earth for billions of years is well..You know we all do that sort of thing (even me). Judge the world by our own personal experience. And it is usually fine for understanding our own local situation. But I have to defer to the scientific community when trying to understand the whole universe. Currently, science really does show that natural selection of genes takes millions of years to create outward change while diet changes can create outward changes in one lifetime.

Second, I later realized I misrepresented you regarding humans and selection. You think civilized humans are not subject to ANY selection, natural or artificial. My first response is what I said before: civilization is too recent in time for us to know. My second response is that for humans to be free from all selective pressure they would have to be exactly equal, reproductively. Meaning that no matter if a person is grossly fat or very skinny, brilliantly smart or mentally retarded, very ugly or very beautiful, a skilled athelete or paralyzed below the neck. etc. every type of person on earth has, on average, exactly the same # of children. I find that difficult to believe. In fact I strongly suspect optimum reproduction occurs right in the middle of all those extremes. Doesn't your gut tell you that, worldwide, average people have the most children and extreme sorts of people have the fewest?

Okay, there is plenty more on this subject but after trying to condense 7 years of zoology and anthropology studies into a short blog format I'll just shut up now. But I hope it is slightly interesting for others, anyway, as it was for me.

programmer craig said...

Hi Liev,

Anyway, will again try to define the most crucial components of evolution: only populations can evolve, not individual organisms and it defined as a sustained change in gene frequency.

But that definition is fatally flawed. There has been no change in the genetics of the population in question, yet you refer to it as evolution. How can that be? It cannot. "Evolution" is a change in the organisms, not a change in the environment.

If there was a nuclear war and the only human survivors were black Africans, there has been a sudden substantial change in human gene frequency. Is that evolution?

Sorry, Liev, but that just doesn't work. I'm frankly shocked if that is what they are teaching in US Universities these days.

OK, me off to watch the Harry Potter movie, I'll comment more wehn I get back :)

programmer craig said...

Oh, two more things before I go! (sorry)

The red shell tortoise example meant to show how a 33% red gene population can suddenly give rise to a 100% red gene population.

Well, the 33% population didn't change, did it? That particular population was already 100% "red shell" before it became physically isolated, no? So the gene frequency of that population did not change.

Likewise with my example of a nuclear war leaving only some black African populations alive. The genetics of those surviving populations did not change. It is the genetics of the other populations that changed (by becoming extinct).

And I still think this ides that any change in genetics can be attributed to evolutionary theory is pretty whacky. There can be NO evolution without natural selection. You have already stated that evolutionary theory states that organisms adapt towards survival in their local environment over time. Where is this required adaptation in selective breeding programs, or in un-natural systems, such as human civilization? I'm not seeing it. And how can there be evolution without adaptation?

Severian said...

Craig, I promised to shut up but I can't leave you hanging, I guess, if you are really trying to sort this out.

Regarding the tortoise example, perhaps I should have explained that a "population" is defined as a group of organisms of one species which actually interbreeds. (Species defined as potential interbreeders) The 3 colors of tortoises were all interbreeding (like human brown and blue eyes) So evolution occurred because a new population was formed with a new gene frequency. If the tortoise population had been split into two equal halves then there would not have been any evolution.

The one belief you have which will always trip you up in trying to understand the natural world is:

"There can be NO evolution without natural selection."

This statement seems to suggest evolution is being used as a direct replacement for God, an intelligent creator. Where everything about every living creature has a designed purpose. Except civilized humans of course who are outside the natural order and therefore blasphemous creations with no real purpose.

But the thing is, you have studied civilized humans all your life and seen all their flaws and mistakes. By comparison the graceful dragonfly or stately deer must seem like models of perfection. But they are not. If you studied dragonflies or deer you'd gradualy notice they are just as screwed up as humans are. All of nature is like that. Not a well oiled, perfectly designed machine but a big crazy mess.

Natural selection has done some pretty fine work over the billions of years it has had to work but there are just so many obvious mistakes and problems it becomes clear there are other forces at work which cause evolution. Adaptation to the environment is only part of the story on why things are the way they are.

My favorite example is the human blind spot. Actually all vertebrates eyes have it. It results because our optic neurons stupidly grow forward from our retinas. As they bundle to form the optic nerve they have to pass backward through the retina to the brain, and the hole in the retina is the blind spot. Insect eyes and mollusk eyes (octopus, squid) are designed right with no blind spot. So why didn't vertebrates with these crappy eyes die off and be replaced by insects or mollusks? Natural selection alone is just too simple to explain that and the thousands of similar examples of nature's glaring imperfections.

You ask, "If there was a nuclear war and the only human survivors were black Africans, there has been a sudden substantial change in human gene frequency. Is that evolution?"

Absolutely, 100% yes! I wish I could direct you to a second opinion if you don't believe me but I don't know how else to assure you but, yes,yes yes! Any biologist would agree. Now future anthropologists digging that site might not recognize the evolution since skin color doesn't fossilize (though they would notice the drastic change in human living range). But if you had the same scenario with only pygmies surviving then that would show in fossil record and be called evolution. They might even call the pygmies a separate species, though we know in reality they are not. (but give the pygmies a million years and they would be a new species)

I'm not sure how to better explain artificial selection except to say once again that what matters is reproduction not survival. Humans can set up conditions so that any trait they choose will produce more offspring.

Which is group is more evolutionarily successful, dogs (or humans) who are muscular, athletic hunters, live to a ripe old age and average 1 offspring or a group of fat, sloppy housebounders who die in middle age but average 6 offspring . The answer is clear.

Fat dogs and lazy cats live because they are symbiotic with humans. If you look at the world it is clear that both humans and dogs are much more succesful species than apes or wolves. They are flat out better at survival and reproduction. There can be no argument.

NOMAD said...

of the memory of the ideal shape, but what makes a snow crystal not different of an anemone of the seas,

blood veins and rivers,

sponges and brains ?

all is already in nature

I don't think there was any evolution of the materiality till the last few years, only adaptation ; but with the possibility of modifying a genome, we 'll get new shapes, new beings, dunno yet if they will be able to reproduct in real life, but virtually and in laboratory it is possible ;

Severian said...

Wow nomad, you are on a whole other plane of understanding. I am guessing you believe in universal consciousness? Something that connects every atom and every galaxy and everything in between.

NOMAD said...

yeah, severian, first I used to have the undefined feeling of that, and now the more I read about this subject the more I get convinced of the reality of it

programmer craig said...

Liev,

Craig, I promised to shut up but I can't leave you hanging, I guess, if you are really trying to sort this out.

But you are leaving me hanging by where you get this theory of evolution that does not include both genetic mutation and natural selection. I've never heard of it, and I can't find it online, either.

That isn't even remotely like what Darwin proposed. Whose theory is that?

Regarding the tortoise example, perhaps I should have explained that a "population" is defined as a group of organisms of one species which actually interbreeds.

I know what a population is.

The 3 colors of tortoises were all interbreeding (like human brown and blue eyes) So evolution occurred because a new population was formed with a new gene frequency.

Your example wouldn't work. If they were actually freely interbreeding, then there wouldn't have been a segment of the population that had different traits than the rest, to have been cut off and isolated.

And in any case, that's STILL not compliant with the theory of evolution, even if we accepted your example at face value, as unlikely as it is.

"There can be NO evolution without natural selection."

This statement seems to suggest evolution is being used as a direct replacement for God, an intelligent creator.


I don't agree. Natural selection is the heart and soul of evolution.

If we can't even settle on what evolutionary theory is then I don't understand how you can think we could have "deeper" discussion of it, if I only would agree with you :)

Your baseline assertion about evolution and what it is, is something I could never agree with. And I don't think Charles Darwin would have, either.

In the next comment I'll put some definitions for evolutionary theory that I can fine. I hope you will put up some sources that explain your version of evolution, as well :)

programmer craig said...

Evolutionary Theory

We see evolution as based on the trial-and-error process of variation and natural selection of systems at all levels of complexity. The name of 'natural selection' comes from the Darwinian theory of biological evolution, which distinguishes "natural" selection from "artificial" selection, where specific features are retained or eliminated depending on a goal or intention (e.g. the objective of a cattle breeder who would like to have cows that produce more milk). The "implicit goal" of natural selection is maintenance or reproduction of a configuration at some level of abstraction. The selection is natural in the sense that there is no actor or purposive system making the selection. The selection we are discussing is purely automatic or spontaneous, without plan or design involved.

Evolution typically leads to greater complexity, although one must be careful how one defines complexity.


Wiki: Evolution

In biology, evolution is the change in the inherited traits of a population from generation to generation. These traits are the expression of genes that are copied and passed on to offspring during reproduction. Mutations in these genes can produce new or altered traits, resulting in heritable differences (genetic variation) between organisms. New traits can also come from transfer of genes between populations, as in migration, or between species, in horizontal gene transfer. Evolution occurs when these heritable differences become more common or rare in a population, either non-randomly through natural selection or randomly through genetic drift.

The theory of evolution by natural selection was first proposed by Charles Darwin and Alfred Russel Wallace and set out in detail in Darwin's 1859 book On the Origin of Species.[5] In the 1930s, Darwinian natural selection was combined with Mendelian inheritance to form the modern evolutionary synthesis,[3] in which the connection between the units of evolution (genes) and the mechanism of evolution (natural selection) was made. This powerful explanatory and predictive theory has become the central organizing principle of modern biology, providing a unifying explanation for the diversity of life on Earth.[6]

Before you talk about "horizontal gene transfer" in this reference being supportive of what you say, I humbly submit that the traits that are transferred horizontally came about a result of mutation and natural selection in one of the populations before they were passed on to another, anyway.

Mechanisms: the processes of evolution

Fundamental to the process is genetic variation upon which selective forces can act in order for evolution to occur. This section examines the mechanisms of evolution focusing on:

* Descent and the genetic differences that are heritable and passed on to the next generation;

*

Mutation, migration (gene flow), genetic drift, and natural selection as mechanisms of change;

*

The importance of genetic variation;

*

The random nature of genetic drift and the effects of a reduction in genetic variation;

*

How variation, differential reproduction, and heredity result in evolution by natural selection; and

*

How different species can affect each other's evolution through coevolution.


Nothing in there about artificial selection, is there?

That's a class Synopsis on Evolutionary Biology at UC Berkeley.

continuing...

programmer craig said...

This is from UC Berkeley's "Evolution 101":

An introduction to evolution

The definition
Biological evolution, simply put, is descent with modification. This definition encompasses small-scale evolution (changes in gene frequency in a population from one generation to the next) and large-scale evolution (the descent of different species from a common ancestor over many generations). Evolution helps us to understand the history of life.

The explanation
Biological evolution is not simply a matter of change over time. Lots of things change over time: trees lose their leaves, mountain ranges rise and erode, but they aren't examples of biological evolution because they don't involve descent through genetic inheritance.

The central idea of biological evolution is that all life on Earth shares a common ancestor, just as you and your cousins share a common grandmother.

Through the process of descent with modification, the common ancestor of life on Earth gave rise to the fantastic diversity that we see documented in the fossil record and around us today. Evolution means that we're all distant cousins: humans and oak trees, hummingbirds and whales.


Notice all the references to "descent with modification". The genetics of an organism have to change for it to be evolution.

I don't know, Liev. I don't think we are just arguing semantics on this one. I think we have a fundamentally different understanding of what Evolutionary theory is. I don't really know how we can debate it when we have a different definition for what the word means, either.

I also don't agree with your statements about diet effecting the )skeletal) size of organisms, either... at least, not with mammals. But that's one of those "more in depth" type of discussions we can't really have until we settle on the basics :)

programmer craig said...

I forgot to highlight parts in that last comment:

Biological evolution, simply put, is descent with modification. This definition encompasses small-scale evolution (changes in gene frequency in a population from one generation to the next) and large-scale evolution (the descent of different species from a common ancestor over many generations). Evolution helps us to understand the history of life.

Changes in gene frequency "from one generation to the next".

You didn't include that part in your examples. Your "evolution" occurred immediately and didn't involve any genetic change in the population at all, it merely isolated them with their current genetic make-up. Same with my example (which you endorsed as "Evolution") in which only some populations of black Africans survived a nuclear war. Not only no generational change in their genetics, but no change in their genetics at all. I can't for the life of me reconcile those examples with all I know and all I can find out about the nature of evolutionary theory.

programmer craig said...

Sorry if I'm seeming brusque now, Liev. I am enjoying the discussion, but I get the feeling you think you are talking to a child. I tried to warn you about the problems my college profs had with me whenever they'd drift off the curriculum into the realm of personal opinions :)

I may not have much formal education but I'm a hell of a lot more intelligent than the average college professor, including my Father who teaches organic chemistry.

Severian said...

Craig,

First I do want to apologize for sounding like I am talking down to you. I knew it could be taken that way and I should have apologized earlier (though I'm not sure I could have changed my language all that much. Keep in mind, I feel very constrained by the limits of this format and I am being very economical with words, not explaining what I think can be deduced. Also these ideas are not mine! If only I was so brilliant. I'm just reporting to you some of the concepts of a field I am very familiar with. These are not my "personal opinions".

As I told you, I had many of the same misconceptions about evolution that you have and changing my mind to see the light wasn't always easy or quick. It took numerous years, courses, textbooks and arguments before I got to the point where I could address the subject at an advanced level. But I don't think of you as a child; if I did, I wouldn't waste my time. You seem like an intelligent adult with an interest in what I think is a fascinating subject.

I thought I'd find an online site going over the basics of evolution but you found some reasonable ones. What you were looking for is there, though perhaps you skimmed over those parts. I think these chapter headings from your posts might be a good starting point (caps mine)to address the issues that are bothering you:

-Mutation, migration (gene flow), genetic drift, AND natural selection as mechanisms of change;

-The RANDOM nature of genetic drift and the effects of a reduction in genetic variation;

How variation, DIFFERENTIAL REPRODUCTION and heredity result in evolution by natural selection; and

How different species can affect each other's evolution through COEVOLUTION (including symbiosis!).

Okay, so, now this from your Wikipedia entry:

"Evolution occurs when these heritable differences (GENES) become more common or rare in a population, either non-randomly through natural selection or randomly through genetic drift."

It is clear: evolution can occur EITHER through a non-random process (natural selection) or a random process (genetic drift AND OTHERS).

It shouldn't be too big a leap to understand that artificial selection is also a non-random process which changes gene frequency. It might not worth mentioning in a primer Biology book because it isn't very important in the grand scheme of things, as I made clear before. Artificial selection only affects a few dozen species and has only been going on 10,000 years. But it is evolution. I'll list these 3 sites for corroboration (there are many more):

http://www.blackwellpublishing.com/ridley/a-z/Artificial_selection.asp

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

http://evolution.berkeley.edu/evosite/evo101/IIIE4Evochange.shtml


Also, I thought it was obvious that a population of all red tortoises or all dark skinned humans would mate and reproduce to make further generations and that's when the evolution takes place.

You are right, btw, I certainly am not interested in a semantic debate. I want to know how the world works, not argue over what names we use. To me, that's what this discussion is about. How the living world got the way it is.

Regarding Darwin, I am very familiar with his work. A truly brilliant guy. He went absolutely as far as he could go without knowing about DNA or genes or chromosomes or mutations etc. Origin of Species is about 600 pages long and he wrote a lot more after that.

Darwin did understand that while natural selection is the primary driver of evolution there are other important factors at work. His work with Galapagos finches on separated islands made it clear he understood the importance of what is now called mutation, migration, isolation and genetic drift for causing evolution.

Darwin even hinted at some of the more cutting edge aspects of modern evolutionary theory including: kin selection, selfish gene theory, game theory, eusociality etc. An amazing guy and, for me an amazing field. I didn't chose to make my living at it but I'll always find it fascinating.

programmer craig said...

Liev,

As I told you, I had many of the same misconceptions about evolution that you have and changing my mind to see the light wasn't always easy or quick.

Then it seems you used to understand Evolution properly, and now you don't. What happened?

Without genetic changes in the organism (not an artificially created change in the frequency at which traits appear, but an actual generational hereditary change in those traits) AND natural selection, you can't have evolution at all.

You have dispensed with BOTH elements of Evolutionary theory - genetic change and natural selection - and you still call it evolution.

I don't know how and why you learned these things, but whatever you are discussing, it isn't evolutionary theory. I'd appreciate it if you stopped calling it a more advance version of Evolutionary theory. It isn't evolutionary theory, at all.

However, I will read the rest of your comment and reply to it, if I can find anything to reply to.

programmer craig said...

-Mutation, migration (gene flow), genetic drift, AND natural selection as mechanisms of change;

-The RANDOM nature of genetic drift and the effects of a reduction in genetic variation;

How variation, DIFFERENTIAL REPRODUCTION and heredity result in evolution by natural selection; and

How different species can affect each other's evolution through COEVOLUTION (including symbiosis!).


Yes, those are all mechanisms for

a) transferring mutated genes between populations. The mutation is still key.

or

b) impacting the survivability of an organism in the local environment, thereby influencing natural selection.

It still comes down to mutation and natural selection.

It is clear: evolution can occur EITHER through a non-random process (natural selection) or a random process (genetic drift AND OTHERS).

Same argument I just made. It still comes down to transfer of traits that were created by mutation, and natural selection.

It shouldn't be too big a leap to understand that artificial selection is also a non-random process which changes gene frequency.

Artificial selection is specifically excluded from the theory of Evolution. What you just said is incorrect, is it not? Darwin himself excluded artificial selection from his theory of evolution, and that exclusion is still in force. You can find the exclusions in the links I posted.

I don't understand why you are claiming that a more "advanced" understanding of Evolutionary theory can be in complete contradiction with the basic tenets of the theory.

That's not logical, and you know how much I like logic :)

It might not worth mentioning in a primer Biology book because it isn't very important in the grand scheme of things, as I made clear before. Artificial selection only affects a few dozen species and has only been going on 10,000 years.

But it was mentioned. Artificial selection is explicitly excluded, Liev.


But it is evolution. I'll list these 3 sites for corroboration (there are many more):

Reading your links and I'll get back to you with my thoughts on them in another comment.

Also, I thought it was obvious that a population of all red tortoises or all dark skinned humans would mate and reproduce to make further generations and that's when the evolution takes place.

That's absurd. There hasn't been any change in their genetics, so what difference does it make if they mate and and pass on their unchanged DNA to successive generations?

Evolution requires a change in DNA.

Now I'm the one who is being condescending, but it doesn't seem that difficult to see that you are arguing semantics :)

You are right, btw, I certainly am not interested in a semantic debate. I want to know how the world works, not argue over what names we use. To me, that's what this discussion is about. How the living world got the way it is.

Me too. And I think clarity is important. The two key elements in evolution are hereditary changes in DNA, and natural selection.

You've dumped both of those elements form the theory, and still call it Evolution. I don't know how you can reconcile that, in your own thoughts.

His work with Galapagos finches on separated islands made it clear he understood the importance of what is now called mutation, migration, isolation and genetic drift for causing evolution.

But, all those factors are in fact based on mutation. The other factors are just mechanisms for transferring mutated DNA from one population to another.

Darwin even hinted at some of the more cutting edge aspects of modern evolutionary theory including: kin selection, selfish gene theory, game theory, eusociality etc.

Why are those more advanced, and why wouldn't Darwin know about that? Seems like common sense and observation, to me.

An amazing guy and, for me an amazing field. I didn't chose to make my living at it but I'll always find it fascinating.

Me too. And I suspect I'm a lot more well read on it than you think.

programmer craig said...

From the link on Artificial selection:

It was originally defined by Charles Darwin in contrast to the process of natural selection, in which the differential reproduction of organisms with certain traits is attributed to improved survival and reproductive ability in the natural habitat of the organism.

Not that in that article, it is pointed out that selective breeding using artificial selection is useful to evolutionary biologists primarily because it allows them to study Evolutionary processes at a vastly accelerated rate.

One of the other links:

With artificial selection experiments, evolution can be studied in the laboratory

Says exactly the same thing. It's a valuable tool for studying the real world results of adding or removing traits to a living organism. It's valuable in that dramatic results can be had in just a few generations, by ruthlessly culling the undesirable specimens and allowing only those with the traits being bred for to reproduce.

The third link didn't say much of anything, at all, so I won't quote form it.

Stating that artificial selection is useful for the study of Evolutionary processes is a far cry from claiming that artificial selection is part of the theory of evolution. It isn't.

But my larger disagreement with you is on the idea that physically culling large parts of a population, or isolating part of a population, has instantaneously caused evolution of that population. It has caused a change, but not an evolutionary change.

programmer craig said...

Finally, I'll address this paragraph in more detail:

His work with Galapagos finches on separated islands made it clear he understood the importance of what is now called mutation, migration, isolation and genetic drift for causing evolution.

1) Isolation. Like when Scandinavians and other Northern Germanic peoples develop blond hair or blue eyes, as survival traits. Largely in isolation, because they lived in a hostile environment (arctic and sub-arctic) and were hostile to outsiders.

Blue eyes and blond hair are the results of mutated DNA.

2) Migration. Like, when the Germans and Scandinavians "migrated" to Gaul, Italy, Spain, North Africa, Asia Minor, Russia, etc.

And their recessive traits for blue eyes and blond hair were transferred to at least some of the local inhabitants (local populations) when they mixed in and merged with them.

3) Genetic Drift This is the random tendency for genetic traits to drift toward becoming more common or more rare, over time. It only applies in populations where the trait in question is neither 100% or non-existent. The smaller a population the more likely it is for genetic drift to remove a trait entirely, or result in 100% incidence of the trait in that population.

Basically, genetic drift influences the incidence of a mutated gene in a population. In my blond hair and blue eyes example, for instance, genetic drift will most likely eventually remove these two recessive traits from human genetics. They are rare, they are recessives, and they are no longer survival factors.

4) mutation I submit all four of these apply to mutation.

None of these factors applies to the examples you gave except isolation. However, the genetic changes in an isolated population occur AFTER isolation, as additional mutations over time occur only in that isolated population, and not in the rest of the population. Your argument that the isolation has itself immediately resulted in evolution work.

NOMAD said...

nothing new under the skies though ! we already knew that your an exceptionnel vestige or the anglo-saxon tribes :lol:

but, unfortunately, your going to desappear ; may-be you could save your lignee if you go to the Cryo bank ; hehe, who knows, you could create a mutation, a Pygmee might grow and get blue eyes, ; blond, that would be aleatory, let say red :lol:

BTW, in roman times, blues eyes were considerated as a desease

Severian said...

Craig, what I earlier suspected is becoming more clear. You are not trying to learn anything or even teach anything but rather just win an argument. I say this because you keep changing your argument hoping to find a way to win, while discarding your disproven arguments without acknowledgement.

First you argued that since some people are near sighted, it proves modern civiliation has eliminated evolution. I carefully explained why that isn't so. I'm sure you just moved on.

You argued there can be no evolution without natural selection. I carefully explained why that isn't so and still no acknowledgement you were wrong. In fact you then try to use the genetic drift model to explain why blonde hair and blue eyes will disappear without evolution (and you get this wrong also; I will explain why below, not that you will admit it).

Next you argued artificial selection is not evolution. I explained why it is and provided several sites which specifically describe artificial selection as evolution. You ignore that and try to cherry pick statements to prove you are once again right. All you have to do is Google, "artificial selection+ evolution" and you'll find hundreds of sites that say the same thing I say, the same thing the sites I provides say and what any evolutionary biologist knows: artificial selection is evolution. If that disturbs your personal theories then I'm sorry but facts are facts. If you'll read the whole site instead of cherry picking them for out of context arguments you'd see what I mean.

Okay, so: We are unlikely to lose blonde hair and blue eyes for reasons, once again, to be found in your own post:

"The smaller a population the more likely it is for genetic drift to remove a trait entirely, or result in 100% incidence of the trait in that population."

Though you claim to know what a population is, I don't think you do. Nor do you understand genetic drift. There is no population of blonde, blue eyed people on earth. Human population is huge, growing and becoming less and less isolated

Genetic drift would be more likely to eliminate blonde/blue if a human population was a group of 100 people on an isolated island and there was only one blonde/blue person. That one person is all too likely to die young or be gay or otherwise fail to reproduce. In a large, non-isolated population that won't happen.

You make further mistakes regarding this issue by stating:

"genetic drift will most likely eventually remove these two recessive traits from human genetics. They are rare, they are recessives, and they are no longer survival factors."

First, "survival factors" are not relevant to genetic drift. Second, recessive genes are MORE likely to survive than dominant genes. You should be able to figure out the reason for yourself. Further, I suspect you are not familiar with the concept of "junk DNA" http://en.wikipedia.org/wiki/Junk_DNA

I really don't see how you expect to understand evolution by focusing on one species (humans) in the past 10,000 years, ignoring millions of other species and billions of years of history. If tunnel vision is all you aspire to then I don't think I can be of help.

I think your main misconceptions come from clinging to the notions of:

1. "Survival of the fittest"
That was never Darwin's term for natural selection. Herb Spencer coined the phrase. He was a 19th century writer trying to justify white British imperialism over the lesser peoples of the world. Focusing on "differential reproduction" will steer you right.

2. Natural selection works to promote perfection and maximum efficiency in all aspects of an organism. It doesn't, only in reproduction and even then it often fails and only works within the concept of "niche"

But you know, if winning is more important than learning then I can see why you had trouble with college professors (including your father?). It isn't as though scholars are the most useful part of society. Quite the opposite, in my opinion.

But you do seem to lack a certain measure of respect. You were a soldier and are a computer programmer? I have no experience in either of those fields while you have devoted years of your life to them. Consider how you would feel if I started to lecture you about being a soldier or programming a computer, making all kinds of false assumptions. And when you tried to set me straight I just argued, changed direction and ignored most of what you said to focus on a few moot points. Would you be as patient with me as I am being with you?

If winning really isn't your ultimate goal, you can learn more on your own, of course. You can explore niche theory on your own, as well as kin selection, selfish genes, etc. Once you can answer why mitochondria have their own DNA and why men have nipples I think you will have arrived ;-).

Severian said...

Haha Nomad, you are not a blondie? Me neither. Doesn't the Bible say that the moderately brown will inherit the earth? ;-)

NOMAD said...

how did you know that I am a bastard French ? :D

dunno about bible, but statistics tend tosay it

programmer craig said...

Liev,

Craig, what I earlier suspected is becoming more clear. You are not trying to learn anything or even teach anything but rather just win an argument.

This is not so. I entered the discussion stating that the two primary tenets of the theory of evolution are a) mutation and b) natural selection.

We can't even agree on that. I don't call it an "argument" when you redefine the theory of evolution to suit yourself.

I say this because you keep changing your argument hoping to find a way to win, while discarding your disproven arguments without acknowledgement.

You haven't dis-proven anything I've said, Liev. I've dis-proven quite a few things you have said, and you have claimed that my understanding of evolutionary theory was too rudimentary and that's why I didn't understand your arguments. Then I resorted to providing links that defined the theory of evolution, that clearly showed your claims were in error, and you have not acknowledged a single mistake.

Your comments about chemistry, for instance. What happened to that? Did you ever acknowledge being wrong, there? That was our first disagreement.

Someplace about 20 comments ago you said that < 10,000 years of civilation was too short a time for it to have effected human evolution. But you have several times given examples that you claim prove a species or a population can evolve immediately, and that evolution is nothing more than a change of genetic frequency in a population. Well, liev, genetic frequency in human populations has changed hundreds if not thousands of times in the last 10,000 years. The human populations of North and South America are a good example of that. And Australia is, as well.

You have contradicted yourself, there.

First you argued that since some people are near sighted, it proves modern civiliation has eliminated evolution. I carefully explained why that isn't so. I'm sure you just moved on.

I didn't just "move on", Liev. We can't even agree about what the theory of evolution is. How can we discuss specific cases?

You argued there can be no evolution without natural selection. I carefully explained why that isn't so and still no acknowledgement you were wrong.

That's because, I'm not wrong. Natural selection is half of the theory of evolution. The other half is mutation. You have dispensed with both. *shrug*

In fact you then try to use the genetic drift model to explain why blonde hair and blue eyes will disappear without evolution (and you get this wrong also; I will explain why below, not that you will admit it).

Whatever.

Next you argued artificial selection is not evolution.

I didn't argue that. Charles Darwin argued that, Liev.

I explained why it is and provided several sites which specifically describe artificial selection as evolution.

Now I will call you a liar. None of the three cites you provided made a claim that artificial selection was part of Evolutionary theory. All three said that artificial selection was a useful tool for evolutionary biologists.

You ignore that and try to cherry pick statements to prove you are once again right.

And no acknowledgment from you that your theoretical about turtle shells has nothing to do with evolutionary theory?

Okay, so: We are unlikely to lose blonde hair and blue eyes for reasons, once again, to be found in your own post:

I'm starting to believe you just aren't bright enough to understand these concepts, Liev. It doesn't seem that difficult, to me. I'm at a loss as to how I am supposed to explain a theory to you that you are incapable of grasping.

The % of the world's population that has the traits for either either blond hair or blue eyes is minute.

Though you claim to know what a population is, I don't think you do.

Why wouldn't I? You carefully explained it to me as if I was a 5 year old, early on :P

Nor do you understand genetic drift. There is no population of blonde, blue eyed people on earth. Human population is huge, growing and becoming less and less isolated

Yes. There is no longer a specific population that has high rates of blond hair or blue eyes.

And since 90% of the earth's population doesn't even have the allele for blond hair or blue eyes, and the < 10% who do are mixing more and more frequently with those who don't, the traits will probably eventually be gone.

Exactly.

Genetic drift would be more likely to eliminate blonde/blue if a human population was a group of 100 people on an isolated island and there was only one blonde/blue person.

Actually, that's entirely untrue.

You make further mistakes regarding this issue by stating:

Further mistakes? I haven't made a single one. On the other hand, you've made nothing but mistakes.

I'm starting to doubt your vaunted education, Liev.

First, "survival factors" are not relevant to genetic drift.

I never said they were. The fact that they aren't survival factors anymore means that they no longer serve any purpose, and will therefor their retention will not be encouraged by natural selection.

You seem to be implying that there can't be more than one evolutionary factor at work at the same time, Liev. Now who is taking the shallow view on evolutionary theory? :O

Second, recessive genes are MORE likely to survive than dominant genes.

That's patently absurd.

I really don't see how you expect to understand evolution by focusing on one species (humans) in the past 10,000 years, ignoring millions of other species and billions of years of history. If tunnel vision is all you aspire to then I don't think I can be of help.

You have made this accusation against me from the start, Liev. The reason I don't think you can be of "help" to me, is that I don't think you know what you are talking about.

I'm going to leave this discussion now. I have no interest in engaging in an insult fest with you. I'll close by saying that if you are a self-proclaimed "expert" on evolutionary theory, then you give expertise a bad name. You seem more like a student who didn't really "get it" but managed to pass tests by memorizing the curriculum. It's no surprise to me that you didn't end up working in your field of study... your level of competence seems pretty low.

programmer craig said...

About the "starting an argument" - you've been patronizing and condescending towards me from the start, Liev. I gently pointed out to you that I was aware of it a couple of times, and did my best to ignore it. But, it continued. I'm not the one who took this discussion on a hostile path.

Severian said...

Craig,

I'm done trying also. You have no curiosity, no interest in learning. I can understand why you wouldn't know the answer to difficult questions like mitochondrial DNA or male nipples but I am sure you have the intelligence to deduce the answer as to why recessive genes survive better. You just don't want to know the answer. You stubbornly cling to your own made up idea that dominant genes survive longer.
(the answer, btw is that when a gene is not expressed phenotyically it is not subject to natural or artificial selection. The link on "junk DNA" would have helped you understand that.

Anyway, I do have a bachelor degree in Zoology and a masters in Anthropology with a 3.6-3.7 GPA. I assure you there are no "memorization" tests in grad school. We learn from seminars, colloquiums, journal readings, paper writing and discussions. If you are not interested in what the academic world has to offer then far be it from me to shove it down your throat.

I am not in the academic world anymore because I chose to apply my skills to directly helping people in need. If you can't respect that or my knowledge and education or degrees then it reflects solely on you. Enjoy your own ideas as they were meant to be enjoyed. Alone.

programmer craig said...
This comment has been removed by a blog administrator.
NOMAD said...
This comment has been removed by a blog administrator.
programmer craig said...
This comment has been removed by a blog administrator.
Daniel said...
This comment has been removed by the author.
NOMAD said...
This comment has been removed by a blog administrator.
Pazuzu said...

Ok people, I really enjoyed the fact that alot of conversation took place in response to my post, I didn't expect that much. But I am not pleased with the negative environement at the end. I strongly ask you all to act nice and everything. I don't really care what happens or doesn't happen between you but I refuse to see it here. I don't like to moderate comments, this is not kindergarden, but I left with no other choice. As far as I am concerned and for as long as this blog is under my supervision and authority I will not toelrate personal insults, please just stop it.

I would like it to be perfectly clear that the people in here are my personal friends and I am more than certain and confident of their intentions and of their qualifications when they speak.