tear ducts

TomS

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Nov 4, 2009, 10:29:48 AM11/4/09

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I was just talking to a friend, who reported his conversation with
a friend of his who was an evolution-doubter. The e-d said that evolution
couldn't explain "the tear duct".

I've never heard this one before.

Have any of you? What is supposed to be the problem with the evolution
of the tear duct?

--
---Tom S.
the failure to nail currant jelly to a wall is not due to the nail; it is due to
the currant jelly.
Theodore Roosevelt, Letter to William Thayer, 1915 July 2

Mitchell Coffey

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Nov 4, 2009, 11:33:12 AM11/4/09

to talk-o...@moderators.isc.org

On Nov 4, 10:29 am, TomS <TomS_mem...@newsguy.com> wrote:
> I was just talking to a friend, who reported his conversation with
> a friend of his who was an evolution-doubter. The e-d said that evolution
> couldn't explain "the tear duct".
>
> I've never heard this one before.
>
> Have any of you? What is supposed to be the problem with the evolution
> of the tear duct?

<sarcasm>
Which evolved first, tear ducts or the tears? If the former, they
would have conferred no advantage; if the latter, tears would have
built up until the creature's head exploded.
</sarcasm>

Mitchell Coffey

r norman

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Nov 4, 2009, 1:04:07 PM11/4/09

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On 4 Nov 2009 07:29:48 -0800, TomS <TomS_...@newsguy.com> wrote:

>I was just talking to a friend, who reported his conversation with
>a friend of his who was an evolution-doubter. The e-d said that evolution
>couldn't explain "the tear duct".
>
>I've never heard this one before.
>
>Have any of you? What is supposed to be the problem with the evolution
>of the tear duct?

Tear ducts are found in pretty much all tetrapods. But there really
is a question of what they are supposed to do. Carrying off excess
tears is not much use -- there is no problem in just having the fluid
run out of the eye. And there is no particular value in shunting it
into the nasal cavity. So the problem is why it should be there at
all.

Willem Hilllenius, the chair of the Biology department at the College
at Charleston, is interested in the Harderian gland in amphibians.
This is a specialized gland in the eye orbit of many tetrapods and
Hillenius (with Susan Rehorek of Slippery Rock University) speculates
that its secretions might be closely connected with the vomeronasal
(Jacobson's) organ, a sensory structure in the nasal passages. They
have a paper in J. Herpetology

WJ Hillenius, LK Watrobski, and SJ Rehorek
Passage of Tear Duct Fluids through the Nasal
Cavity of Frogs
J. Herpetology 35(4):701-704 ( 2001)
http://www.jstor.org/pss/1565918

showing that the lacrimal duct transmits fluid from the Harderian
gland to the vomeronasal organ. Thus the secretions of the gland could
be used to bind to and carry scents, especially pheromones, picked up
from the air (or water in the case of amphibian animals) to the
sensory structure. The Harderian gland - tear duct - vomeronasal
organ connection seems to be shared by, for example, frogs and
caecilians (among the amphibians) and snakes (among the former
Reptiles) and so was probably an important factor in early tetrapod
evolution. Using the large, moist exposed surface of the eye to
collect scents is probably as effective as the snake habit of flicking
out its tongue to capture odors for presentation to the vomeronasal
organ.

Desertphile

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Nov 4, 2009, 1:30:20 PM11/4/09

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Yes, but it's *STILL* salt water!

--
http://desertphile.org
Desertphile's Desert Soliloquy. WARNING: view with plenty of water
"Why aren't resurrections from the dead noteworthy?" -- Jim Rutz

TomS

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Nov 4, 2009, 1:45:51 PM11/4/09

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"On Wed, 04 Nov 2009 11:30:20 -0700, in article
<f1i3f514610hp31tg...@4ax.com>, Desertphile stated..."

>
>On Wed, 4 Nov 2009 08:33:12 -0800 (PST), Mitchell Coffey
><m.co...@starpower.net> wrote:
>

>> On Nov 4, 10:29=A0am, TomS <TomS_mem...@newsguy.com> wrote:
>> > I was just talking to a friend, who reported his conversation with

>> > a friend of his who was an evolution-doubter. The e-d said that evolu=

>tion
>> > couldn't explain "the tear duct".
>> >
>> > I've never heard this one before.
>> >

>> > Have any of you? What is supposed to be the problem with the evolutio=
>n
>> > of the tear duct?
>=20

>> <sarcasm>
>> Which evolved first, tear ducts or the tears? If the former, they
>> would have conferred no advantage; if the latter, tears would have
>> built up until the creature's head exploded.
>> </sarcasm>

>=20

>Yes, but it's *STILL* salt water!

I like that.

I'm tempted to bring up something like that whenever a creationist
speaks about the supposed impossibility of a particular evolutionary
transition - let's say between the jaw-bone of a reptile and the
middle-ear bone of a mammal: "It's still a bone."

TomS

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Nov 4, 2009, 1:50:51 PM11/4/09

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"On Wed, 04 Nov 2009 13:04:07 -0500, in article
<4qe3f51bb0ak76lin...@4ax.com>, r norman stated..."

Thanks. I'll pass this on to my friend.

TomS

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Nov 4, 2009, 1:50:56 PM11/4/09

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"On Wed, 04 Nov 2009 13:04:07 -0500, in article
<4qe3f51bb0ak76lin...@4ax.com>, r norman stated..."
>

Thanks. I'll pass this on to my friend.

TomS

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Nov 4, 2009, 1:50:57 PM11/4/09

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"On Wed, 04 Nov 2009 13:04:07 -0500, in article
<4qe3f51bb0ak76lin...@4ax.com>, r norman stated..."
>

Thanks. I'll pass this on to my friend.

Bob Casanova

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Nov 4, 2009, 2:58:34 PM11/4/09

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On 4 Nov 2009 07:29:48 -0800, the following appeared in
talk.origins, posted by TomS <TomS_...@newsguy.com>:

>I was just talking to a friend, who reported his conversation with
>a friend of his who was an evolution-doubter. The e-d said that evolution
>couldn't explain "the tear duct".
>
>I've never heard this one before.
>
>Have any of you? What is supposed to be the problem with the evolution
>of the tear duct?

There is no problem; creationists tend to grasp at illusory
straws.
--

Bob C.

"Evidence confirming an observation is
evidence that the observation is wrong."
- McNameless

John Wilkins

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Nov 4, 2009, 9:30:07 PM11/4/09

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In article
<a9f7c7a6-4c79-462a...@m26g2000yqb.googlegroups.com>,
Mitchell Coffey <m.co...@starpower.net> wrote:

Of what use is half a tear duct?

J. J. Lodder

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Nov 5, 2009, 2:49:18 AM11/5/09

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John Wilkins <jo...@wilkins.id.au> wrote:

It can still tear,

Jan

Tom McDonald

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Nov 5, 2009, 2:44:09 AM11/5/09

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On Nov 4, 8:30 pm, John Wilkins <j...@wilkins.id.au> wrote:
> In article
> <a9f7c7a6-4c79-462a-b8f8-0d11c6dcf...@m26g2000yqb.googlegroups.com>,

>
>
>
> Mitchell Coffey <m.cof...@starpower.net> wrote:
> > On Nov 4, 10:29 am, TomS <TomS_mem...@newsguy.com> wrote:
> > > I was just talking to a friend, who reported his conversation with
> > > a friend of his who was an evolution-doubter. The e-d said that evolution
> > > couldn't explain "the tear duct".
>
> > > I've never heard this one before.
>
> > > Have any of you? What is supposed to be the problem with the evolution
> > > of the tear duct?
>
> > <sarcasm>
> > Which evolved first, tear ducts or the tears? If the former, they
> > would have conferred no advantage; if the latter, tears would have
> > built up until the creature's head exploded.
> > </sarcasm>
>
> Of what use is half a tear duct?

The evolution of Glen Beck?

Ken Denny

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Nov 5, 2009, 8:48:30 AM11/5/09

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On Nov 4, 1:04 pm, r norman <r_s_nor...@comcast.net> wrote:
> The Harderian gland - tear duct - vomeronasal
> organ connection seems to be shared by, for example, frogs and
> caecilians (among the amphibians) and snakes (among the former
> Reptiles)

Snakes are former reptiles? What are they now if they're no longer
reptiles?
Although the class Reptiles is not a good classification since snakes
and lizards share a more recent common ancestor with birds than they
do with turtles.

r norman

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Nov 5, 2009, 11:03:55 AM11/5/09

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On Thu, 5 Nov 2009 05:48:30 -0800 (PST), Ken Denny <k...@kendenny.com>
wrote:

That is what I meant. The "new reptiles" include birds and the "old
reptiles", the ones that people think of as reptiles, are extinct --
the word, that is, not the animals.