I submit Fish. Obvious that he still has some ways to go yet.
Posted on 12/21/2004 4:13:57 PM PST by beavus
The human parathyroid gland, which regulates the level of calcium in the blood, probably evolved from the gills of fish, according to researchers from King's College London.
Writing in the latest edition of Proceedings of the National Academy of Sciences, Professor Anthony Graham and Dr Masataka Okabe suggest that the gills of ancestral marine creatures, which were used to regulate calcium levels, were internalised rather than lost when land-living, four-limbed animals – the tetrapods – evolved.
Many physiological processes such as muscle contraction, blood coagulation and signalling by nerve cells, require specific levels of calcium in the body. In humans, calcium levels are regulated by the parathyroid gland, which secretes parathyroid hormone if the calcium concentration in the blood falls too low. This hormone then causes the release of calcium from bone, and increases its reuptake in the kidney, raising the calcium levels back to normal.
Fish don't have parathyroid glands. Instead they increase their internal calcium concentration by using their gills to take up calcium from the surrounding water.
'As the tetrapod parathyroid gland and the gills of fish both contribute to the regulation of extracellular calcium levels, it is reasonable to suggest that the parathyroid gland evolved from a transformation of the gills when animals made the transition from the aquatic to the terrestrial environment,' said Professor Graham.
'This interpretation would also explain why the parathyroid gland is positioned in the neck. If the gland had emerged from scratch when tetrapods evolved it could, as an endocrine organ, have been placed anywhere in the body and still exert its effect.'
The researchers supported their theory by carrying out experiments that show that the parathyroid glands of mice and chickens and the gills of zebrafish and dogfish contain many similarities.
Both gills and parathyroid gland develop from the same type of tissue in the embryo, called the pharyngeal pouch endoderm; both structures express a gene called Gcm-2, and both need this gene to develop correctly.
Furthermore, the researchers found a gene for parathyroid hormone in fish, and they discovered that this gene is expressed in the gills.
'The parathyroid gland and the gills of fish are related structures and likely share a common evolutionary history,' said Professor Graham. 'Our work will have great resonance to all those people who have seen Haeckels' pictures, which show that we all go through a fish stage in our development. This new research suggests that in fact, our gills are still sitting in our throats – disguised as our parathyroid glands.'
Ahem ... you r ignorance is showing ... . There is no need to revel in it. God is a spirit. Jesus is God in the flesh and He is NO APE!
I feel sorry for you ... you ridicule Someone you don't know. Do you often ridicule those you don't know to feel superior? Or to justify your ignorance? Never mind ... you don't have to dig yourself a deeper hole.
Oh, I see. Humans and apes did not have a common ancestor because Jesus is no ape. Okay. I'm glad we have that brilliant bit of deduction straight.
Why do you guys do this to yourselves? Surely you know better.
The genius of Darwin is revealed by the fact that today, you wonder how anyone could have ever thought otherwise. Of course Darwin was clued in by contemporary discoveries in geology which began to reveal just how old the earth is.
Imagine. Before Darwin people believed, in spite of their everyday experience of continuous time and space, that people just poofed in out of nowhere. Of course the whole idea is absurd, and except for the creationist cult, it is commonly recognized as such.
This is the fundamental genetic defect of creationists. Despite their everyday ubiquitous use and observation of continua, they do not comprehend continua. They will tell you they comprehend them, but then when they describe them you realize they are clueless! They live and breathe the fallacy of the beard. It seems genetic, anyway, but I know it is really just the power of the cult over the mind.
I don't think all people believed in "poof". There was the discussion about passing on acquired traits, for instance.
When you look at the old legends, all peoples tried to come up with rational sounding causes of life. The ToE doesn't contain anything about creation, so I can never figure why the creationists insist it does.
You're right. I was far too glib. Pre-Darwin folks were not all as nutty as creationists.
"Oh, I see. Humans and apes did not have a common ancestor because Jesus is no ape. Okay. I'm glad we have that brilliant bit of deduction straight.
Why do you guys do this to yourselves? Surely you know better."
Where does one begin to address such a sorry reply?
Not only are you illogical but spiritually discerned and proud of it. I pity you.
Apparently one doesn't.
Right...and the answer was ...NOT a million generations...since that's 20-22 million years by the assumption of a generation time.
Well said.
I submit Fish. Obvious that he still has some ways to go yet.
You conveniently left out the word "generations," which was clearly stated in my original post (copied below):
So exactly how many generations do I have to go back before I have a monkey in my family tree? Ten thousand? A million? There is no evidence of human beings existing that far back.
1 million generations is 20-22 million years.
At what point will human beings evolve into an entirely new, more advanced species? Your genetics are determined at conception as a result of the combinating of your parents' DNA, and at no point in your life will your DNA be altered by the surrounding environment (notwithstanding radiation and cancer, which have a reverse, or devolutionary effect).
Children's DNA is a combination of parents' DNA. Carried forward a million generations, any offspring's DNA will STILL be a product of the parents' genetic mixing.
If evolution is responsible for the creation of new species, what is forcing the mutation of genes to produce new species, and why haven't we seen any evidence of it yet?
Part of your conceptual difficulty with the issue of evolution is revealed by your choice of words "...at what POINT will human beings evolve..." and "...genetics are determined AT conception...". This reflects a lack of understanding of the continuous nature of biologic phenomena. The statements would be more insightful if they were phrased as "...how is the PROCESS of human evolution manifest..." and "...genetics are determined DURING conception...".
There may, but need not be, and it would seem unreasonable to expect, that a new species would originate in one generation. There are many genes that need to be expressed in the reproductive process. By the time enough changes are made to constitute a new species, there may no longer be an survivors of the previous species, especially if the gene pool remains mixed.
Children's DNA is a combination of parents' DNA. Carried forward a million generations, any offspring's DNA will STILL be a product of the parents' genetic mixing.
As you've alluded to above, there are documented means of changing the genetic material to something other than what the parents supply. There is no requirement that point mutations be deleterious, as you suggest, which is why mutation is usually theorized to be the means of creating entirely new genes. Their rarity is why this theory is favored by large numbers of generations (both serial and in parallel--i.e. large populations).
Statistically, point mutations are unlikely to be expressed at all. If they are expressed, they are likely to be deleterious. However, natural selection is the bias against traits deleterious for a particular environment and in favor of traits advantageous for an environment. So, new advantageous traits needn't be common, since nature favors them when they occur.
If evolution is responsible for the creation of new species, what is forcing the mutation of genes to produce new species, and why haven't we seen any evidence of it yet?
A great question. The causality in your wording again seems to reveal a conceptual difficulty. You ask "what is FORCING the mutation of genes to produce a new species...?" Of course the appropriate way to view the process is that there is a sea of phenotypic changes in a changing biological system, some of which favor greater reproduction than others. That is, the only FORCE involved comes from predators, disease, the elements, and other factors of nature that lead to a creature's death before it can reproduce. The more genetic variability there is within a population, the more likely there will exist traits conducive to survival within an environment.
The other part of your question alludes to how those phenotypic changes occur. It is well documented in living systems that genetic changes, whether recombination or mutation, can produce phenotypic changes. Recombination and mutation are not well understood and are frequently modelled as random processes. Physical phenomena, such as ionizing radiation, can cause point mutations, and so there are theories about radiation sources, like cosmic rays, affecting the rate of genetic change in an ecosystem.
In the end, there are many observed facts which any theory needs to explain, such as:
(1) Physical (and therefore biological) phenomena above quantum scales are continuous.
(2) For all species, and indeed all life on earth, there was a time before it existed and a time after it existed.
(3) A creature's reproductive success is affected by its environment.
(4) A creature's reproductive success in a particular environment is affected by its expressed traits.
(5) Many expressed traits are genetically determined.
(6) Offspring usually express some different traits than their parents.
(7) Genetic mutations occur.
(8) Different species alive today express common traits and common genes. In some species those traits appear to have no function.
(9) The fossil record is a series of snapshots in time.
(10) The fossil record shows examples of temporal series of morphologically similar creatures.
There is (and always will be) much to be explained, but it is understandable why evolutionary science dominates efforts to explain current biological diversity and the fossil record.
Give me a break!
"They evolved together."
Huh? Or, to put it more succinctly, Huh?
Maybe if I start putting diesel fuel in my car, my car will evolve a diesel engine!!!
Huh? Or, to put it more succinctly, Huh?
Does poofism cripple the mind, or is it an incapable mind that is prone to poofism? The point was that evolution is just that--evolution. An Arabian stallian likely did not pop out of the womb of an eohippus.
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