Biology Wednesday, December 8, 2004 . This is a SciScoop post by Ricky James
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.’
Text for this article comes from a King’s College press release.
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2 Responses to The Gland That Evolved From Gills
Sweetwind
December 9th, 2004 at 9:25 am
Isn’t it true that Haeckel’s pictures were faked? That is, Haeckel deliberately misdrew them to support his strict recapitulationist stance. Why is this not common knowledge among scientists?
Most of the links I can find about this in a casual search are anti-evolution sites, *tsk*. Can’t scientists admit and publicize our failures? I was just reading about this in Stephen Jay Gould’s I Have Landed.
Anonymous
December 10th, 2004 at 3:31 pm
How is this a new finding? I remember learning about this in my undergraduate endocrinology class a quarter century ago!
As for faking- Haekel, Mendel, Ptolomy all "cleaned up" or added to their findings to make them more convincing and ensure their own personal influence (though as in the case of Mendel it doesn’t always work). Didn’t mean they were entirely wrong, just that they understood the nature of competition in the human world of ideas and "what it takes" to win. That’s a lot different from wholesale fabrication.
The problem in our society here is that showmanship and the loudest voice often win out over actual priority and careful analysis and scrupulous presentation. As Gilbert & Sullivan once observed (I don’t remember which operetta): "If you wish in the world to advance, your (?) you’re bound to enhance- You must stir it and strump it and blow your own trumpet, or trust me you haven’t a chance". I’m not sure about the second line particular, either.
Internalization of glands isn’t a new idea, please note. Its been long known that the lower pituitary gland, which is in higher vertebrates attached directly to the blood vessels, originated as an open pocket in the roof of the mouth of lower chordata. Similarly the thyroid was an open pocket in the bottom of the mouth, dumping its cargo of iodine-containing hormones directly into food as it passed to the gut. The entire history of all the in- and out-pocketings found in complex bodies has similar stories- teeth from scales, external genitalia from internal ones in cloacas, testes in scrotal sac dropping out from the old ovary position inside the body, and so on.
codemaniac