Popular arguments for 'bad design' often feature "vestigial organs",
which are claimed to be useless, and their presence in the human body is
touted as evidence of common descent, and also of the non-teleological
nature of the same. However, it is imprudent, nay, foolish, to assume
that because we might not know a function of something, the same has no
function. Indeed, such a non-sequitur prevents further research, for who
would endeavor to study something which has no function. However,
sooner or later, a stroke of luck might enable a researcher to find
functions for what had hitherto been considered useless. And we see that
this has occurred repeatedly. Yet, the champions of the Darwinist
paradigm still espouse these outdated claims. Physicist Dr. Karl
Giberson in his tirade against Intelligent Design Theory on 'The Daily
Beast' claims:
"We carry the evidence of this long history in our bodies—features useful to our ancestors but, for various reasons, not to us." [1]
One of the example he gives is that of the plica semilunaris, a fold of conjunctiva in the eye, which is homologous to the nictitating membrane in non-primates. He writes:
"We have a bunched-up third eyelid in the corner of our eye that provided a transparent eye covering for our ancestors, allowing them to “blink” without have to fully shut down their vision." [2]
But is the plica semilunaris merely a useless remnant of the nictitating membrane? Not really:
According to Duane's Clinical Ophthalmology, the plica has the following function:
"In humans, the plica functions as the opposite of a fornix; that is, if the conjunctiva were to directly join the eyelids to the globe, the globe and eyelids would both be restricted in movement. The fornix provides for a fold of conjunctiva that may be extended or retracted as the globe moves. Extension occurs because of fibrous slips that connect the fornix to its extraocular rectus muscle. As the muscle contracts, the globe rotates and the adjacent conjunctiva is retracted. This occurs above, laterally, and below the globe, but not medially, which would not allow the lacrimal puncta to drain the lacrimal lake. On abduction the plica tends to unfold and flatten, whereas on adduction it is drawn posteriorly and is unfolded by the fibrous slips that extend to the plica and caruncle from the medial rectus. While it never completely unfolds, extreme adduction of the plica causes it to form a true fornix. As this occurs, a small movement of the globe occurs as a result of the retraction of the medial canthal tendon. This keeps the lacrimal puncta properly positioned with the lacrimal lake. The puncta now dips into the lacrimal strip to allow continuous drainage despite the position of the globe. In addition, the plica helps to maintain the lacrimal lake in its proper position and location in the puncta." [3]
So contra the wild claims made by Darwinist storytellers, real science keeps finding functions for "vestigial" organs, and thereby vindicates time and again the teleology inherent in biological systems.
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References:
[1] http://www.thedailybeast.com/articles/2014/06/01/the-crazy-way-creationists-try-to-explain-human-tails-without-evolution.html
[2] http://www.eyecalcs.com/DWAN/pages/v8/v8c002.html#pli
"We carry the evidence of this long history in our bodies—features useful to our ancestors but, for various reasons, not to us." [1]
One of the example he gives is that of the plica semilunaris, a fold of conjunctiva in the eye, which is homologous to the nictitating membrane in non-primates. He writes:
"We have a bunched-up third eyelid in the corner of our eye that provided a transparent eye covering for our ancestors, allowing them to “blink” without have to fully shut down their vision." [2]
But is the plica semilunaris merely a useless remnant of the nictitating membrane? Not really:
According to Duane's Clinical Ophthalmology, the plica has the following function:
"In humans, the plica functions as the opposite of a fornix; that is, if the conjunctiva were to directly join the eyelids to the globe, the globe and eyelids would both be restricted in movement. The fornix provides for a fold of conjunctiva that may be extended or retracted as the globe moves. Extension occurs because of fibrous slips that connect the fornix to its extraocular rectus muscle. As the muscle contracts, the globe rotates and the adjacent conjunctiva is retracted. This occurs above, laterally, and below the globe, but not medially, which would not allow the lacrimal puncta to drain the lacrimal lake. On abduction the plica tends to unfold and flatten, whereas on adduction it is drawn posteriorly and is unfolded by the fibrous slips that extend to the plica and caruncle from the medial rectus. While it never completely unfolds, extreme adduction of the plica causes it to form a true fornix. As this occurs, a small movement of the globe occurs as a result of the retraction of the medial canthal tendon. This keeps the lacrimal puncta properly positioned with the lacrimal lake. The puncta now dips into the lacrimal strip to allow continuous drainage despite the position of the globe. In addition, the plica helps to maintain the lacrimal lake in its proper position and location in the puncta." [3]
So contra the wild claims made by Darwinist storytellers, real science keeps finding functions for "vestigial" organs, and thereby vindicates time and again the teleology inherent in biological systems.
----------------------------------------------------------------------------------------------
References:
[1] http://www.thedailybeast.com/articles/2014/06/01/the-crazy-way-creationists-try-to-explain-human-tails-without-evolution.html
Thanks, Sri!!
ReplyDeleteI can't actually name a single legitimate "Vestigial" organ.