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.'
Humans.!.. (Eddie Murphy laugh)
In the womb, for a short time, we all have gills.
At first it was a possiblity -- until researchers concluded cukes lack the "curvature gene."
Yes. But, only if we are able to call other celestial bodies...HOME.
Yep,.....Great Theologian was John Gills!
LOL
Merry Christmas Carols Joy!
:-)
/sarcasm
: : ::keyboard spew!:: : : :
rofl!
Then surely gourds could be a possibility. :)
Jim, I'm an atheist, but I'll be damned if that doesn't almost make sense.
This article represents some of that evolutionary developmental biology ("evo-devo") which gets mentioned on FR threads sometimes. According to creationists, any idea of embryology relating to anything else is "discredited by science." Meanwhile, scientists haven't got the word.
Yeah, I know. I am a biologist and a minister. ;-)
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.
it is reasonable to suggest
experiments that show that the parathyroid glands of mice and chickens and the gills of zebrafish and dogfish contain many similarities.
Somebody explain to me how "probably" or "resonable to suggest" and "many similarities" constitute scientific evidence that human beings evolved from FISH!
Well, of course, that's because it's only "science" if the study is being performed by a graduate of BTIT (Bible Thumpers Institute of Technology).
Really intelligent people know that evolution is a fact and the theory of evolution explains that fact.
"If sound science appears to contradict the Bible, we may be sure that it is our interpretation of the Bible that is at fault." Christian Observer, 1832, pg. 437
"Christians should look on evolution simply as the method by which God works." Rev. James McCosh, theologian and President of Princeton, 1890
Oh good - the search continues for nonexisting "evidence."
I was thinking of another organ that could have been used to suck oxygen while submerged on ones back. I can also submit proof of same as evidenced by one Lewinsky giving ah........never mind
Yeah, on 'Mutant Porno Planet' :-D
Interesting quotations.
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