Define 'species'

[Ondoher]

"The position of A. afarensis in the phylogeny of early humans is under debate. Many feel that it is ancestral to the east African "robust" early humans, and possibly to all robust forms. Additionally, A. afarensis is proposed as the ancestor to later Homo. Yet, research now suggests that A. africanus might be ancestral to later Homo."

The phylogeny of this fossil is not clearly demonstrated in fact its skull(430cc) is not that different from the modern chimpanzee. "From this, it is clear that there are many significant difference between A. afarensis and its ape predecessors, one of which is crucial to later human evolution, bipedality."

This is all good stuff. Nothing about a transitional implies it is necessarily in a direct line of lineage between any set of taxa. If fact, fossils cannot really tell you that. However, Lucy is representative, and likely closely related to, the kind of species that would have been in direct lineage. In otherwords, Lucy looks exactly like a transitional should.

The crucial demonstration here has to be the bipedality, here is how they determined that a transition was underway. It is actually a composite of three specimans, "composite reconstruction based on several specimens, the famous Laetoli footprints, and the AL 129".

Are you claiming Lucy was a composite, not a single specimine. I'd like to see that supported. For the sake of argument, lets pretend that's correct. Where did they find the bipedal pelvis and knees. They are nicely intermediate between humans and apes.

This is based on questionable phylogeny and peicemeal forensics. This is only one example of how these supposed transitions are fitted together to fit the philosophical premise.

The "philosophical premise" was that a large brain was the first characteristic to develop. The fossils actually told a different story.

"OH 62 has raised more questions than she has answered.

Like good science should.

Where did the later species of Homo come from? Cranially, Homo habilis is more similar to later Homo, and many consider this to be the true lineage. But the emergence of early humans with modern body proportions in a relatively short time, while not impossible, gives some researchers cause for concern, and they look to other lineages, such as Homo rudolfensis. (Click to see a representation of the two implied phylogenies)

Additionally, this confuses the evolution of early humans at the level of Australopithecus afarensis and A. africanus. Which lineage gave rise to later Homo? The body proportions of A. africanus have been found to be more ape-like than the earlier A. afarensis. Paradoxically, this may place A. africanus as the ancestor of Homo-- if, in fact, the early members of our genus had ape-like body proportions like OH 62."

Yes, there is still no strong consensus on the most likely phylogeny. Science is like that. That is what makes it fun. Nobody is suggesting, however, that these fossils are not in our family tree, just the precise placement.

In order for a species to be determined in natural history there has to be a defining speciman. The fossil evidence represents scarce and highly peicmeal forensics.

These two sentences do not seem to be related, nor does the conclusion appear to be supported.

 

[mark kennedy]

This is all good stuff. Nothing about a transitional implies it is necessarily in a direct line of lineage between any set of taxa. If fact, fossils cannot really tell you that. However, Lucy is representative, and likely closely related to, the kind of species that would have been in direct lineage. In otherwords, Lucy looks exactly like a transitional should.

I was talking about AL 129 and OH 62. Lucy came along later when the Austropthicenes were allread established as a species in paleontology.

Are you claiming Lucy was a composite, not a single specimine. I'd like to see that supported. For the sake of argument, lets pretend that's correct. Where did they find the bipedal pelvis and knees. They are nicely intermediate between humans and apes.

What I was talking about was the Austrapithecus afarensis was identified as a new species. They are clearly some kind of apes and the Lucy and the Hadar specimens are more primitive then the ones that Leaky found. The crucial definition of man includes an upright posture. The point being that these creatures have much more in common with Pan paniscus (pygmy chimpanzee) and is most likely the direct descent of the Australopithecine specimens.

The "philosophical premise" was that a large brain was the first characteristic to develop. The fossils actually told a different story.

Like good science should.

For one thing good science tests hypothesis and if the crucial point of demonstration is found to fit the hypothesis it becomes a theory. The hypothesis didn't hold up as new data came to light so they created a new one. Now the whole thing is more convoluted the the original linear model, this has thrown the whole taxonomic scenerio into a state of flux. Science is supposed to determine truth and demonstrate it, this mess just confuses the issues since it fits the facts into previous assumptions.

Yes, there is still no strong consensus on the most likely phylogeny. Science is like that. That is what makes it fun. Nobody is suggesting, however, that these fossils are not in our family tree, just the precise placement

Thats because people like Leaky and Johnson are trying to find the human ancestor, its not like they ever look for a more realistic line of descent. Thats what happens when you force the fact to fit your presumptions.

These two sentences do not seem to be related, nor does the conclusion appear to be supported.

Thats your opinion and you haven't really got a handle on the facts as I presented them.

 

[Pete Harcoff]

That is a really big if Pete, to say nothing of the fact that recursion is largely a matter of conjecture. At best it represents an hypothesis that has yet to be demonstrated.

So are you suggesting mutations don't become fixed in gene pools? (I thought we were passed this, but...)

 

[mark kennedy]

So are you suggesting mutations don't become fixed in gene pools? (I thought we were passed this, but...)

Its not that it doesn't ever happen, its just the extent to which they are credited with evolutionary change.

 

[USincognito]

Bipedality can be determined from just a skull by the shape and placement of the Foramen Magnum.

 

[mark kennedy]

Bipedality can be determined from just a skull by the shape and placement of the Foramen Magnum.

Ok, I'll bite, how do you figure?

 

[USincognito]

Ok, I'll bite, how do you figure?

The foramen magnum is located posteriorly in non-bipedal apes because the spine goes into it like a plug into back, whereas it's more centrally located (some sources I just double checked say "anteriorly" others "ventrally" in reference to the skull) on the skull of a biped in order for the spine to go up into it like a hatrack.

The location of the foramen magnum on a skull is a key indicator as to whether the owner of that skull walked upright.

 

[yossarian]

anterior and ventral are the same basically

 

[Tomk80]

Its not that it doesn't ever happen, its just the extent to which they are credited with evolutionary change.

Mark, I've said it earlier and I'll say it here again. I don't get your position. You didn't answer my last post were I tried a couple of questions to see whether you'd clear up your position, but maybe here.

You say beneficial mutations don't happen to the extent were they are credited in evolutionary change. However, you yourself admitted that for your model to work, you need evolution to happen quicker than in even the quickest models of evolutionists.
Now, for this you need beneficial mutations for evolution to happen, and apparently you need them in a rate which exceeds evolutionists' models. On the other hand however, you say they almost never occur and can't give the extent of change predicted by evolution. How do you clear up this contradiction?

 

[USincognito]

anterior and ventral are the same basically

I agree but the skull of a bipedal tetrapod poses a bit of a quandry.

Our posterior is both our buttocks, but it's also our rectum. Our dorsal should be our back, but the "top" of our bodies is our cranium. Our anterior should be our face since it's on the "front", but it also is directed "down" meaning it's part of our ventral. And then there's the feet, they're our ventral, unless we're supine, when they actually are our anterior.

Or perhaps my confusion is having taken A&P 19 years ago.

The point about the location and angle of the foramen magnum being an indication of bipedalism isn't lost regardless of the terms used though, so we'll wait for Mark to request a clarification if necessary.

 

[gluadys]

anterior and ventral are the same basically

No, not really.

If you look at your basic bi-lateral body plan (ignoring limbs), you can compare it to a rectangle in which the horizontal lines are longer than the vertical ones. (Kind of like a side view of a mattress lying on the floor).

Anterior refers to the front or head end.
Dorsal to the back or top side.
Posterior to the rear or tail end.
Ventral to the belly or bottom side.

Now with bipedalism, it's as if you stood the rectangle, (mattress) on end so now the vertical lines are longer than the horizontal lines. This rotates all of the above designations 90 degrees.

Anterior moves from front to top.
Dorsal moves from top to rear.
Posterior moves from rear to bottom.
Ventral moves from bottom to front.

It's easy to get confused because "anterior" and "posterior" generally mean "before" and "behind", but in most animals that's where the head and tail are, whereas an erect posture puts these at top and bottom. "Ventral" and "dorsal" are anatomical terms for "stomach" and "back" and in most animals these are found respectively on the bottom and top of the body. But in a bi-pedal organism like ourselves, our anatomical back is also found on the back of the body, allowing for a confusion of anatomy with locality.

 

[mark kennedy]

Mark, I've said it earlier and I'll say it here again. I don't get your position. You didn't answer my last post were I tried a couple of questions to see whether you'd clear up your position, but maybe here.

You say beneficial mutations don't happen to the extent were they are credited in evolutionary change. However, you yourself admitted that for your model to work, you need evolution to happen quicker than in even the quickest models of evolutionists.
Now, for this you need beneficial mutations for evolution to happen, and apparently you need them in a rate which exceeds evolutionists' models. On the other hand however, you say they almost never occur and can't give the extent of change predicted by evolution. How do you clear up this contradiction?

For one thing I don't consider the changes in gene frequencies to be mutations at all, frankly I consider it to be providential. Given the normal healthy gene pool the amount of change grows not from competition but from an abundance of resourses. Scarcity would hamper growth and develpment and by the same token a mutated gene would diminish diversity not inhance it. Perhaps I am mistaking the term mutation and confusing it with Darwin's monstrocity or Richard Goldschmidt's 'hopefull monster', I don't know for sure. I realize that terms like deviate and mutation are meant to covey the idea of a change that are neither good nor bad just different.

That may be where I'm losing you, I'm still trying seperate the ideals of naturalistic methodology and the dynamics of genetic change. I'm trying to track down USincognito's concept right now but I'll get back to this shortly.

 

[Tomk80]

For one thing I don't consider the changes in gene frequencies to be mutations at all, frankly I consider it to be providential. Given the normal healthy gene pool the amount of change grows not from competition but from an abundance of resourses. Scarcity would hamper growth and develpment and by the same token a mutated gene would diminish diversity not inhance it. Perhaps I am mistaking the term mutation and confusing it with Darwin's monstrocity or Richard Goldschmidt's 'hopefull monster', I don't know for sure. I realize that terms like deviate and mutation are meant to covey the idea of a change that are neither good nor bad just different.

But if we start out 4000 years ago with two individuals of each 'kind', so with a maximum of four alleles per kind, how can we have gotten all the diversity which is present nowadays, other than through these mechanisms? What other mechanisms do you propose and what observations do you have for these mechanisms.

That may be where I'm losing you, I'm still trying seperate the ideals of naturalistic methodology and the dynamics of genetic change. I'm trying to track down USincognito's concept right now but I'll get back to this shortly.

My apologies if I am a bit fuzzy, but thanks for answering my question as best you can, I do have a better understanding of your position now.

 

[gluadys]

For one thing I don't consider the changes in gene frequencies to be mutations at all, frankly I consider it to be providential.

You are right in saying a change in gene frequencies does not imply mutation. What you are overlooking is that in order for a change in gene frequencies to occur, there must be alternate forms (alleles) of a gene. Where did these alternate forms come from?

You say it is providential. That depends. If in considering the original creation of say, sheep, your contention is that God began with a pair of sheep---then there can be, at maximum, only four alleles of any given gene. So if current sheep display more than four alleles of any given gene, you need to explain where the additional alleles came from.

Now if, instead of a single pair of sheep, God began with a population of 100,000 sheep, this difficulty is overcome.

But it crops up again with the flood. Sheep, as clean sacrificial animals, were taken onto the ark in seven pairs: 14 animals. Maximum limit of alleles per gene=28. That is enough for a great deal of variety. But, it does not explain the existence of any gene in more than 28 alleles. And some genes do exist in much more than 28 forms.

The only known means of generating new alleles is mutation. I raised this very question in the Creationist forum

http://www.christianforums.com/t808635

and was referred to AiG articles which confirmed this is the case.

Given the normal healthy gene pool the amount of change grows not from competition but from an abundance of resourses. Scarcity would hamper growth and develpment and by the same token a mutated gene would diminish diversity not inhance it.

I don't understand what you mean here by abundance/scarcity of resources, but there is no reason why all, or even most, mutations would diminish diversity. Why do you come to this conclusion?

Perhaps I am mistaking the term mutation

I think this qualifies for understatement of the year.

 

[mark kennedy]

Bipedality can be determined from just a skull by the shape and placement of the Foramen Magnum.

I think you are talking about the Taung Child", Australopithecus africanus that Raymond Dart found in 1924 and he said the same thing about the Foramen Magnum. The problem was that it was a juvenile and the central location was readily accounted for because of its age. It wasn't untill 1940 that there were other specimans found that were catogorized Australopithecus afticanus based on their teeth that his work was finally accepted. The Forament Magnum doesn't really stand alone although it might suggest bipedality if the postition can't be accounted for in some other way.

Its an interesting point, made for some interesting reading.

 

[mark kennedy]

But if we start out 4000 years ago with two individuals of each 'kind', so with a maximum of four alleles per kind, how can we have gotten all the diversity which is present nowadays, other than through these mechanisms? What other mechanisms do you propose and what observations do you have for these mechanisms.

Actually with creationism you have more like 6,000 to 10,000 years ago. Timeline in the OT are mostly based on genologies (most likely abbreviated) that are in turn based on a lunar calander. Obviously you are not going to get millions of years out of a strict literal reading no matter how many allowances you make for the omissions.

My apologies if I am a bit fuzzy, but thanks for answering my question as best you can, I do have a better understanding of your position now.

No problem, I probably should have made the distinction between the analogy of mutation and the science of genetic change. Its gradualism that I have major problems with, not the dramatic change in populations over time.

 

[Pete Harcoff]

Its not that it doesn't ever happen, its just the extent to which they are credited with evolutionary change.

It's gradualism that I have major problems with, not the dramatic change in populations over time.

After reading these two statements, I am completely confused as to what you are going on about. It looks like a glaring contradiction, but I'm sure you can explain it.

 

[mark kennedy]

You are right in saying a change in gene frequencies does not imply mutation. What you are overlooking is that in order for a change in gene frequencies to occur, there must be alternate forms (alleles) of a gene. Where did these alternate forms come from?

At the risk of getting my head bit off, I would have to say meiosis. This may well be the extent to which I accept random variations as an explanation for diversity.

You say it is providential. That depends. If in considering the original creation of say, sheep, your contention is that God began with a pair of sheep---then there can be, at maximum, only four alleles of any given gene. So if current sheep display more than four alleles of any given gene, you need to explain where the additional alleles came from.

Now if, instead of a single pair of sheep, God began with a population of 100,000 sheep, this difficulty is overcome.

But it crops up again with the flood. Sheep, as clean sacrificial animals, were taken onto the ark in seven pairs: 14 animals. Maximum limit of alleles per gene=28. That is enough for a great deal of variety. But, it does not explain the existence of any gene in more than 28 alleles. And some genes do exist in much more than 28 forms.

The only known means of generating new alleles is mutation. I raised this very question in the Creationist forum

http://www.christianforums.com/t808635

and was referred to AiG articles which confirmed this is the case.

I checked out AIG and I found this:

"Actually, two genomes (male and female) could have four different alleles (variety of a given gene) between them for each gene locus, not two. Since you say you are a professional biologist, I assume you just made a simple mistake here and you actually do understand the principles of genetics.

Now, there are probably some 30,000 genes in a wolf/dog, and if every gene locus were heterozygous (two different alleles), then for each gene there are 10 possible pairs of four types of allele (if the alleles are A, B, C, D; then the possible pairs can be easily tabulated: AA, AB, AC, AD, BB, BC, BD, CC, CD, DD — for n types of allele, the number of possible pairs is n(n+1)/2).

With the recombinations due to sexual reproduction, this amounts to a potential number of different genotypes in the descendants of 10^30,000 (this is 1 followed by 30,000 zeros). To put this in perspective, there are thought to be some 10^80 atoms in the Universe! So, it appears that two wolves could produce quite a few descendants before the pattern would have to be repeated! Now because not every gene locus is likely to be heterozygous in the original pair, and because of recessive alleles not every gene will be expressed, so the number of animals that could actually be different in their form (‘phenotype’) would be less than the huge number above.

But let’s be ultra-generous to the evolutionist. I.e., let’s assume (as you claimed) that there were only two types of allele per locus, and that there was no co-dominance so only two phenotypes per locus, and there was only 1% heterozygosity in wolves/dogs (cf. 6.7% in humans even today, presumably much less than in Adam and Eve), the number of possible varieties would be 2^300 = 10^300(log(10)2) = 10^90. Even with these conservative figures, this number is still so huge that it makes the number of atoms in the universe seem like a tiny smattering — 10^90/10^80 = 10^10 (10 billion) times larger!"

A Pair of Wolves on Noahs Ark...

There is also a link to another article on the Creationist view on mutations if your interested.

I don't understand what you mean here by abundance/scarcity of resources, but there is no reason why all, or even most, mutations would diminish diversity. Why do you come to this conclusion?

A couple of things, first I happened across a nature article that described the lush jungles of Southern Veitnam where they were finding an enormous variety of species. I have also heard this and that about rainforests having an unparalleled number of varieties. When I started reading about the fossils found in Southern Africa I couldn't help but wondering if they represent an exotic variety that emerges from lush regions where resources are very plentifull. That coupled with the fact that most mutations are deleterous or harmfull seems to suggest something that runs counter to the naturalistic 'survival of the fittest' that permeates modern philosophies of science in biology.

I think this qualifies for understatement of the year.

Nice dig...

 

[mark kennedy]

After reading these two statements, I am completely confused as to what you are going on about. It looks like a glaring contradiction, but I'm sure you can explain it.

I am not really sure I can explain since I failed to see how these two statements contradict, but I'll do what I can. Notice in the response to gluadys the geometric potential of gene alleles. This is roughly why I don't accept the mutation concept as the primary cause of changes in species. I have often been told that I don't understand genetic drift, ring species, and nested hiearchies but I not only understand I am more dependant on these concepts the most Darwinians. The real difference is the amount of time it would take, you may be aware that transitionals happen relativly suddenly in the fossil record.

 

[gluadys]

At the risk of getting my head bit off, I would have to say meiosis. This may well be the extent to which I accept random variations as an explanation for diversity.

Meiosis is one process. Mutation is another. Mutation often happens during meiosis. That is not a reason to confuse the two processes.

If (as is usual) meiosis occurs without a copying error, no new allele has been generated. You only get a new assortment of existing alternates.

It is only when you have an error in the copying process during meiosis (i.e. a mutation) that you get a new allele. So you are still back to mutation as the only source of new alternate gene forms.

I checked out AIG and I found this:

As is usual they are obfuscating the issue by using a bait-and-switch technique from the question of how much variation exists for one gene to how much variation exists through the whole genotype. I dealt with that in post 6 of the Noah's Ark thread. Let me recapitulate here:

I said:
"You can get tremendous overall variety by mixing a very limited number of options for each particular characteristic.

Take faces for example: suppose we have only two options per characteristic

e.g thin or bushy eyebrows, brown or blue eyes, straight or "ski-slope" nose, light or dark skin colour, full or thin lips, weak or jutting chin. With just two options for just these six characteristics one can generate 64 different faces. If we increased the options to four per characteristic we get 4^6=4,096 different faces.

And the more characteristics you look at, the more variation you can get. No problem there.

My question was directed at how much variety one could get in each separate characteristic.

But what if God originally created an animal kind with 10 different alleles in one gene locus? This would mean creating a minimum of 5 of that kind, since each individual can only carry two of the ten alleles. Now, Noah takes only two of most kinds, so there is necessarily a selection of at best 4 of those 10 alleles. So where does the information come from to recreate a species that originally had 10 alleles at one gene locus? How does a species get back the six missing alleles?

This is where the article on bears came in:"

However, it is likely that not all the features for today’s bears would have been coded for directly in the genes of the original bear kind. Mutations, genetic copying mistakes which cause defects, may on rare occasions be helpful, even though they are still defects, corruptions or losses of information. Thus, the polar bear’s partly webbed feet may have come from a mutation which prevented the toes from dividing properly during its embryonic development. This defect would give it an advantage in swimming, which would make it easier to survive as a hunter of seals among ice floes.

http://www.answersingenesis.org/cre...20/i4/bears.asp

Later I was also referred to this article in aig's feedback section where Carl Wieland states:

"I would believe that the various alleles of hemoglobin, for instance, could easily have arisen by mutation."

Note that there are over 200 different alleles for hemoglobin.

A couple of things, first I happened across a nature article that described the lush jungles of Southern Veitnam where they were finding an enormous variety of species. I have also heard this and that about rainforests having an unparalleled number of varieties. When I started reading about the fossils found in Southern Africa I couldn't help but wondering if they represent an exotic variety that emerges from lush regions where resources are very plentifull. That coupled with the fact that most mutations are deleterous or harmfull seems to suggest something that runs counter to the naturalistic 'survival of the fittest' that permeates modern philosophies of science in biology.

Interestingly, I found you raised this same question on the Noah's Ark thread and I had already answered it there.

Lush jungles offer a wider variety of different niches in which a wider variety of species can find a place for themselves relatively free from competition. Deserts don't offer such a variety of context, so competition for the few niches is more severe and leads to only one or a few species surviving in each niche.

As for the deleterious and harmful mutations, you need to ask "deleterious and harmful to whom"? To the organism or to the species?

Unquestionably to the organism. But the mechanism of natural selection acts as a barrier to prevent the spread of deleterious and harmful mutations to the species as a whole. So not to the species. It loses the input of one or a few organisms to the next generation and carries on as usual.

With beneficial mutations, you get the opposite response. Then natural selection acts to spread the beneficial mutation rapidly through the whole species. That is why natural selection acts as a ratchet, allowing species to accumulate beneficial mutations while not being set back by harmful ones.

Nice dig...

Ah, it's always nice to be appreciated.