Evidence from endocrine system Hi Guys I was reading 'Evolution' by A Franklin Shull (McGr

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Evidence from endocrine system Organization: RHBNC, University of London From: zhah033@vax.rhbnc.ac.uk (Pnn) Message-ID: <1993Jun25.150520.1@vax.rhbnc.ac.uk> Newsgroups: talk.origins Hi Guys I was reading 'Evolution' by A Franklin Shull (McGraw Hill, 1936) (*), which goes over the evidence for evolution. (ie, descent with modification from a common ancestor). Chapter two deals with comparative anatomy; and one of the points he's trying to make is that the precise anatomical position of certain glands in vertebrates is irrelevant to their function, and this is evidence for evolution, because they can be found in exactly the same anatomical position in all vertebrates - and why should this be so, if they can be positioned anywhere in the body? Specifically, he cites certain parts of the endocrine system - the thyroid, pituitary and thymus glands - and the reproductive organs (actually, he talks about the endocrine secretions of the reproductive organs). He says they're always found in the same position in all vertebrates ("near the front gill slits", "at the base of the brain", and "in the neck region or upper part of the chest for several classes of vertebrates" respectively, for the first three (page 20)), and then points out that their effects are widely distributed round the body. He also claims their positioning is irrelevant to their function. How does he know this? Well, from page 20: "The conclusion that these organs might be elsewhere and still serve the same purpose is not mere conjecture. It has been proved by grafting them into strange situations, or by introducing their secretions artificially at other points." Does anyone know where I can read up more on these experiments? IMO, finding details of anatomy that could be different but aren't makes for some pretty good evidence, and this is the only book I've come across that addresses this point. There's also the problem that what he's saying seems slightly dubious. Isn't there a feedback mechanism built into the endocrine system, that it makes sense that some glands (the pituitary - isn't that influenced by the hypothalamus?) be where they are? email, please: I'll won't be able to access the Net for much longer. Thanks Dave (*) why'm I reading a book so long outdated? Because I've got a weird library, whose sole book with a more than elementary modern treatment of the biological evidence for evolution seems to be 'The Science of Evolution'/William D Stansfield, that's why. Maybe I haven't looked hard enough. -- This little piggy is the Captain This little piggy's Number One Dave Ratna This little piggy senses emotions zhah033@vax.rhbnc.ac.uk This little piggy has none And this little piggy runs level 2 diagnostics when the warp coils act funny.


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