Comment on An apology to PUC by Sean Pitman.
@Eddie:
Despite its limitations, the biological species concept works just fine with most vertebrate taxa.
I agree. The biological concept of isolated or largely isolated breeding pools certainly has some utility. However, when the topic at hand is specifically concerned with the potential and limits of the mechanism of RM/NS to produce changes over time, the concept of “species” is not an adequate measure of either the potential or limits of RM/NS.
There are very many similar or extremely similar taxa that live together in sympatry but never, rarely or occasionally interbreed, demonstrating that they are discrete biological entities–what biologists refer to as species by virtually any definition. If they’re not species, what else would you call them? Maybe your definition is more akin to a genus–which is a subjective taxonomic level although there have been attempts to apply biologically meaningful definitions.
The demonstration of a discrete biological entity is one thing. The demonstration that this discrete entity has evolved something functionally unique that was not already present in the ancestral gene pool is quite another – certainly when it comes to the evolution of higher levels of novel functional complexity.
Discrete entities can therefore evolve. If you want to define these discrete entities as “species” and their evolution as “macroevoltuion” that’s fine. Just qualify what you mean when you use the term “macroevolution” in conversations about the potential and limits of RM/NS since many use this term to refer to non-functional as well as high-level functional differences between various gene pools.
The mere ability to interbreed does NOT define a biological species. A good biological species is not necessarily completely reproductively isolated from other populations. The best criterion is free or random interbreeding among individuals. Occasional interbreeding with another taxon does not mean that they are freely interbreeding. Mallards have hybridized with many different species of ducks, especially in captivity when their choices are limited, but Mallards generally prefer to breed with their own species. Hybrids with other species occur in the wild, but they are relatively rare.
The same is true for many human ethnic groups which are free to “randomly” interbreed with other ethnic groups, but tend to prefer their “own” group. The same is also true for various breeds of dogs, cats, chickens, etc. Many of these breeds actually prefer to mate with their own particular breed. Yet, even when interbreeding is significantly or entirely limited (as between a chihuahua and a Great Dane), the different breeds or ethnic groups are still given the very same species classification.
Again, all that the potential to interbreed and produce viable offspring really means is that the two gene pools are essentially the same when it comes to the basic types of functional options available. The lack of the ability to produce viable offspring is a good clue to the probable lack of functional compatibility between the genomes of two organisms. Depending upon the level of functional complexity that makes up the functional difference between two gene pools the mechanism of RM/NS may or may not be able to reasonably account for the functional differences within a given span of time.
If you want to call higher level functional evolution “megaevolution”, that’s fine. It is just that this term is not well defined in mainstream literature. This means that in conversations like this one, over the potential and limits of RM/NS, you need to define your terms up-front because terms like “species” or “macroevolution” or “megaevolution” are not defined with any kind of limitation to RM/NS in mind in mainstream literature… which is a problem.
Sean Pitman
www.DetectingDesign.com
Sean Pitman Also Commented
An apology to PUC
@OTNT_Believer:
Must you keep harping on the one statement on Darwin’s finches that few other than yourself and maybe some other creationists disagree with?
I have yet to see you present one phenotypic or genetic difference between any of Darwin’s Finches and other members of the Dome-nest Clade which could not be rapidly realized in a few thousand years. Certainly a 0.3% difference in cytochrome b isn’t a significant problem. I’m not sure what else makes you think that Darwin’s Finches are no uniquely evolved that they could not be explained as originating from Noah’s Ark a few thousand years ago?
As far as your arguments for the date of the first Egyptian dynasty being preceded by over a thousand years of cultural development, it simply doesn’t take very long for groups of humans to develop complex cultures and governments. Also, there are those who argue that the date for the first dynasty is more likely to be less than 4,500 years ago. Either way, the dating of Egyptian dynasties is hardly a very solid basis for challenging the historical SDA position on origins…
Sean Pitman
www.DetectingDesign.com
The “striking phenotypic differences, and even unique genetic differences†among different populations of humans and dogs are the results of random mutation, genetic drift, natural selection or (in the case of dogs) artificial selection–not “some span of reproductive isolation.â€
It doesn’t matter how the reproductive isolation is achieved, be it “artificial” or “natural”. The resulting phenotypic differences are much more obvious between certain breeds of dogs or even various human ethnic groups than between certain “cryptic” species.
The reason why cryptic species are given taxonomic status while various breeds of dogs and human ethnic groups are not seems arbitrary to me. There really is no clear dividing line for taxonomic status on the one hand, but not on the other…
Humans don’t depend on the color or texture of eyes, hair and skin to avoid mating with chimps or apes, or even different groups of humans.
Are you kidding me? Humans are indeed biased in the choice of a mate toward those of similar phenotypic appearance. While this is not a universal rule (as is also the case with many kinds of cryptic species who also experience the occasional hybrids), it is certainly a bias.
When a female poodle is in heat, it doesn’t matter what “breed†a male dog belongs to, it is equally stimulated and could care less about the length, color or texture of eyes, hair, ears, snout, legs, tail, etc. The reproductive isolating method between dogs (genus Canis) and foxes (genus Vulpes) is likely based on olfaction rather than external morphology.
Have you considered the efforts of a Great Dane to mate with a chihuahua? Come on now, there are clear examples of not only artificial but natural reproductive isolate between various breeds of dogs and even between various human ethnic groups. Aborigines have arguably experienced some time of natural isolation, as have numerous other ethnic groups of modern and ancient humans. Unique phenotypic and even genotypic features were realized that are arguably more significant than the differences between the songs or nest structure of cryptic species of birds or the other very minor variations between cryptic species of frogs or giraffes, etc…
Again, don’t pretend like this is entirely objective science. It isn’t. There is a a fair amount of subjectivity in play here…
Sean Pitman
www.DetectingDesign.com
An apology to PUC
@OTNT_Believer:
And the fact that taxonomists use a b it of subjectivity is a new revelation? Come on Sean, you are nitpicking. Of course there is some subjectivity.
Hey, I’m not the one who came out and said that the differences between Darwin Finches and all other birds were so dramatic and clear cut and objectively understood that they could not be reasonably explained in just a few thousand years… or that the Egyptian dynasties are definitively known to go back over 6,000 years (when they probably go back no more than 4,500 years)…
A “bit” of subjectivity involved here? – no?
Sean Pitman
www.DetectingDesign.com
Recent Comments by Sean Pitman
After the Flood
Thank you Ariel. Hope you are doing well these days. Miss seeing you down at Loma Linda. Hope you had a Great Thanksgiving!
The Flood
Thank you Colin. Just trying to save lives any way I can. Not everything that the government does or leaders do is “evil” BTW…
The Flood
Only someone who knows the future can make such decisions without being a monster…
Pacific Union College Encouraging Homosexual Marriage?
Where did I “gloss over it”?
Review of “The Naked Emperor” by Pastor Conrad Vine
I fail to see where you have convincingly supported your claim that the GC leadership contributed to the harm of anyone’s personal religious liberties? – given that the GC leadership does not and could not override personal religious liberties in this country, nor substantively change the outcome of those who lost their jobs over various vaccine mandates. That’s just not how it works here in this country. Religious liberties are personally derived. Again, they simply are not based on a corporate or church position, but rely solely upon individual convictions – regardless of what the church may or may not say or do.
Yet, you say, “Who cares if it is written into law”? You should care. Everyone should care. It’s a very important law in this country. The idea that the organized church could have changed vaccine mandates simply isn’t true – particularly given the nature of certain types of jobs dealing with the most vulnerable in society (such as health care workers for example).
Beyond this, the GC Leadership did, in fact, write in support of personal religious convictions on this topic – and there are GC lawyers who have and continue to write personal letters in support of personal religious convictions (even if these personal convictions are at odds with the position of the church on a given topic). Just because the GC leadership also supports the advances of modern medicine doesn’t mean that the GC leadership cannot support individual convictions at the same time. Both are possible. This is not an inconsistency.
