Population Bottleneck

#383

There is no requirement that the new species be “more complex”, it may be less complex, as with many parasitic species or blind cave fish which have lost their eyes. Humans have lost tails, which makes us, in one sense, less complex than our Catarrhine ancestors.

You also have the problem of how you measure complexity. If you are looking at increases and decreases in complexity, then you need an objective measure of complexity. We already know that observed evolutionary changes can increase complexity in both the Shannon and Kolmogorov measures. The duplications and mutations in the globin gene family are a good example.

rossum

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#384

It is not required for micro-evolution, but it is required for macro-evolution. If macro-evolution aims to show the feasibility of forming the entire gamut of complex life forms presently existing in the world from the simple self-reproducing organisms of the past, then the alleged evidence for macro-evolution better be able to show the emergence of greater complexity or increased functional information in the species deriving from a parent species. People are sometimes misled into thinking that the difference between micro-evolution and macro-evolution is that micro-evolution refers merely to genetic changes within a species, while macro-evolution refers to genetic changes that result in a new species (speciation). I don’t think so. What is required is not merely evidence of the evolution of a new species, but also one that shows the emergence of new or increased genetic information.

One measure might be the Functional Sequence Complexity (FSC), but that is more for the experts who are looking at the organism in the molecular level. For most of us, the laymen interested on this subject, we would usually consider a proposed evidence for macro-evolution acceptable if the new species, for example, produces a new organ (not just a duplicate organ) that it never had before. The mere modification or duplication of an existing body part or organ, such as the lengthening or shortening of the legs of the lizards in the Bahamas islands, is not good enough because it does not betray an increase in functional genetic information.

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#385

Ah… We are back to Humpty Dumpty argumentation. There is no scientific requirement for more complexity. As I pointed out, there are species which are less complex than their ancestors.

Then humans are not a “new species” on your definition. There is no part of the human body that does not also exist in a chimpanzees body. Not one. The proportions are different, chimps have relatively longer arms and shorter legs, but all parts in a human are also present in a chimp. The reverse is not true; male chimps possess a baculum, which human males do not. Are you trying to tell us that humans are not a new species, but are merely a baculum-less version of a chimp?

You really need to think through these strange personal word definitions of yours before you suggest them.

rossum

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#386

Just wondering - what’s your definition of “empirical?” I suspect that may be the problem.

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#387

There’s no requirement of complexity for macro-evolution, and as others have pointed out, complexity is a pretty troublesome metric. It’s not really one biologists use. Differential reproductive success is pretty much the metric of evolution, and that could lead to more more complexity, no change in complexity, or even less complexity (depending on how you define complexity). Pick your metric and you can get a different answer. I could say humans are the most successful organism because we build jet airplanes and send probes to Pluto. Or I could say E. coli are the most successful because the sheer weight of their biomass may be greater than any other species out there.

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#388

There’s no such thing as “creation science”. Creationism, or what I guess we should call special creationism, was never a science.

The fact is that we have an enormous body of evidence for evolution; the twin-nested hierarchy being the strongest. The most parsimonious explanation is that all extant organisms evolved from an early progenitor population somewhere around 3.5-4 billion years ago.

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#389

“Empirical” means verifiable by observation or experiment.

It is a logical requirement to establish macro-evolution. If macro-evolution affirms the emergence of complex life forms from simple forms, then any evidence for it must show the emergence of a species more complex (or with more genetic information) than the parent species. (Note: A logical requirement is a requirement of reason. Therefore, it must be satisfied in whatever intellectual discipline it happens to pertain, be it science, mathematics, philosophy, theology, etc.)

Yes, there are species less complex than their ancestors. In that case their evolution cannot be used as evidence for macro-evolution. They may be used as evidence for micro-evolution, or maybe even for devolution, but not for macro-evolution.

But, Rossum, my post did not attempt to define a “species.” It defined what type of evidence would serve as acceptable evidence for macro-evolution.

Of course, humans are a distinct species. And, yes, they share similar features with the chimpanzees and other primates. But humans did not evolve from the chimpanzees! And we don’t have to go as far as the evolution of man either. All we need is empirical evidence that a species has given rise to another species that has more genetic information that it originally had. There is no evidence for that, so far.

Remember, the simplest self-reproducing organism has over 500,000 base pairs of DNA information. But every human cell has 3 billion base pairs. What brought about this increase in genetic information that led to the evolution of man? You say macro-evolution. Fine. Then show me how an organism can give rise to another organism that has a richer genetic code than it has. And I do not merely mean an organism with more DNA. Because an increase in DNA can result from duplication and repetition of the same code, which does not help to explain macro-evolution. What is needed is the emergence of a richer genetic information that gives an organism more versatile function, such as genetic information for making feathers in reptiles to push the evolution of birds.

Please do not hesitate to respond even if I cannot respond right away. I keep going away, but I will be back.

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#390

and predictable.

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#391

Big time wrong. Humans had no tails.

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#392

aka devolution.

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#393

It is only a logical requirement for the average complexity of new species to exceed the average complexity of earlier species. As long as the average increases, individual species may be less complex, of the same complexity of of greater complexity, with the third category dominating the average. If ten new species are more complex, three new species are of the same complexity and one new species is less complex, then the average complexity is increasing.

Evolution adapts species to the environment in which they live. If the environment becomes less complex then there is an advantage to reducing complexity so as to waste less of the available resources. Caves have no light so cave fish lose their eyes so as not to waste resources. The absence of light is a reduction in complexity of the cave environment. Evolution tracks that reduction, resulting in a decrease in the complexity of fish living in that environment.

Macro-evolution in biology is defined as the emergence of new species, and higher clades. A new species is macro-evolution, at least in biology textbooks. I do hope that you are not following buffalo down the Humpty Dumpty route and redefining words to suit your argument.

rossum

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#394

aka evolution. A change in DNA is evolution. A new species is macro-evolution.

rossum

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#395

I don’t think that’s true. Not in the way secular science defines it.

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#396

You object to investigating the formal and final causes?

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#397

The tree of life has fallen and is now a tangled bush. You must be aware of this by now.

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#398

Your claim is that everytime there is a split the offspring are better?

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#399

No it hasn’t fallen. It’s just bushier at the base.

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#400

That certainly wouldn’t be a position any biologist would take. “Better” is simply too vague a metric. Differential reproduction means certain traits either bequeath some modest increase in the statistical likelihood of a gene being passed on, or at least do not cause any significant detriment to passing genes on. But there is no optimization in evolution, and a trait that in one environment may prove beneficial, can, in another environment be quite the opposite.

Evolution, plainly stated, is the change in a genetic makeup of a population over time. It isn’t about better or worse, it’s simply the fact that there are evolutionary forces; mutation, neutral drift, chromosomal changes, and, at least in some single-celled populations, also horizontal gene transfer (this happens in multicellular organisms, but how much that influence evolution is much harder to sort out). But HGT doesn’t really help Creationism either, and in fact, certain kinds of HGT, like endogenous retroviral insertions, are actually fairly handy molecular “clocks” for when various populations may have split.

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#401

The biologist might just ignore the noise factor too. Noise is the enemy of every system and is degrading.

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#402

The word “evolution” has two meanings. The first meaning is the meaning in the mind of the common people: it represents the descent of all living organisms from a simple form of life. Would you not agree that this is what the word means for the man in the street? I am aware that the textbook definition of “evolution” is that it is any change in an interbreeding population over time. But, honestly, majority of the common folks do not know that definition. Their idea of evolution is descent of all living organisms from a simple form of life, which is their common ancestor.

In fact, this idea persists even in the mind of many scientists who say that it is not the textbook definition of evolution. Their own work betrays it. Here, for example, is a typical phylogenetic tree of life that you might find in books or in the internet:

Image credit: https://commons.wikimedia.org/wiki/File:Phylogenic_Tree.jpg


Does this picture not give you the impression of descent of all forms of life from a common ancestor? Does it not tell you, in graphical form, what scientists actually believe regarding the origin of various phyla of organisms? Whether they admit it or not, the word “evolution” denotes the rise of complexity and diversity from a primitive life form.

Now, I happen to call the rise of diverse and complex forms of life from a primitive life form “macro-evolution.” Actually, I can call it with a different name. I can call it “super-evolution” instead of “macro-evolution,” if that will make you feel better. It doesn’t matter to me because I am not playing word games here, and a rose by any other name is still a rose. My critique is not against the term, but against the idea of descent of complex forms from a simple form.

So, do not tell me anymore that complexity is not required. Not only is it required, but it IS the issue in any controversy regarding evolution. My contention is that there is NO evidence that all those phyla of organisms that you see in the phylogenetic tree above originated from a common ancestor. And, if you believe that there is evidence for that, then that evidence must show the rise of complexity, or else it is not a valid evidence. Merely to show that B descended from A is not enough. To be acceptable as evidence for super-evolution, your evidence must show that the descent of B from A is accompanied by an increase in genetic information.

Don’t get me wrong, though. I am not saying that the evolution of complex forms did not happen, or that it was impossible. Actually, I think that it is a brilliant idea. My only point is that it is still an unproved brilliant idea.

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