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.'
"Why would an intelligent and benevolent God put the same mistake into both our genetic codes,"
I believe in God. I just think He is smarter than the creationists.
As to being benevolent, God was just establishing the basis for the orange juice industry. Pretty benevolent, eh?
I am not Godless and you are not a Christian for saying that.
I am a devout Christian and a minister of the Gospel to the homeless.
Merry Christmas!
Remember the lyrics to the song the scarecrow in the wizard of Oz sang?
So which one is your distant relative? Was it your grandma taking it from the ape, or was it your grandpa giving it to the ape?
Proof is indisputable. I looked at your links and I don't see any of my ancestors. Tell me, exactly how many generations back will I find an ape in my family tree?
Don't tempt me like that.
Give me the name of all of your own Great-great-great-great-great-grandparents.
To say that the exact lineage of evolution is unknown is as honest as admiting that you have no idea who your own family on your mother's mother's father's father's mother's mother's father's side was not all that many generations ago.
Since you decided to be crude, I will answer that direct question by replying:
"Neither one of them since my grandparents never mated with anyone in your family."
Now that we both have the immature and stupid taunts out of the way,.................
Modern man gradually changed over countless generation to become what he is today. Selective pressures decided what traits were passed on and what traits were not passed on.
Do you believe that some wolf gave birth to a Chihuahua once upon a time to create Chihuahuas?
Do you believe that Chihuahuas were created at the Garden of Eden?
Were there Chihuahuas when Christ was born?
Where did Chihuahuas come from?
I have studied evolution. I used to think in the same way you do. I get what you're saying. But after giving the evidence a fair and honest evaluation, I came to the conclusion that human existence could not possibly have started with an explosion. This is a conclusion based upon my evaluation of the data. I can justify my conclusion based on the validity of my assumptions.
You choose to accept the theory that man has not existed consistently in his present state since creation. This is a belief, but it is not hard science.
My belief is different. Both dogmas have equally as much evidence, but in uniquely different forms. Mine is documented human history, and yours is a scientific theory. Your theory is derived from the scientific method, which considers language such as "probably" and "have many similarities" to be concrete evidence of a conclusion that is not necessarily supported by the paleoantropological evidence.
Just because there is fossil evidence of other species who existed prior to humans, and who have some similarities in physical appearance, does not definitively prove that I have a gorilla or a monkey or a fish in my family tree.
My parents had two parents. Their parents had two parents. And so on and so on. At no point will you reach a juncture where a baboon or an amoeba occupies a branch on my family tree.
God created Chihuahuas.
Why would He purposefully break the gene that's in apes and humans, but leave it functional elsewhere? Cuz he likes us getting sick?
Well, a sense of humor is fine, until someone gets hurt. His "intelligent" design doesn't seem to be too great, if you look at things like putting the urethra through the prostate--a gland that has a tendency to swell up. I suppose the inguinal canal cracks you up, too?
Male nipples are mostly benign, as are goosebumps, but if He knew how to make a good efficient eyeball like the squid's, why not let humans have it. Of course, those cave fish don't need eyes, but it sure is a hoot to see them!
And you know, just like we have broken genes for vitamin C, dolphins have them for smell. But that one I don't get...can you explain the punchline for me?
(Don't worry, I do think the ostrich wings are hilarious...)
Oh, and how about those hips the snakes have? I thought perhaps it had something to do with the Garden of Eden, but it turns out that whales have unused hip bones too...so I don't get the joke.
"Thanks, you've been a great audience tonight...
and, don't forget... ...Appendix!!" >rimshot<
>crowd laughs uproariously< 
Hmmm. I thought you were born of parents.
Uh, actually, there is.
I'd say more like 9 parts supposition and 1 part observation.
I of course did no such thing. I merely characterized your description of Him.
You mischaracterized my posts in a transparently deceitful manner.
The fact is those descriptions of Christ appear nowhere in my posts.
They appear ONLY in your posts.
How do you determine who is a genuine believer? God wants to know.
God doesn't need to ask me.
I determine such things according to His own Word, the Holy Bible.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.