Freethought & Rationalism Archive

scigirl · 06-09-2002, 08:35 AM

I'm stealing this out of Michael Shermer's intro to Why People Believe Weird Things:

He talks about spandrels, which is Gould's and Lewontin's metaphor for a necessary by-product of an evolved mechanism.

Quote:

To ask, "What is the purpose of the spandrel" is to ask the wrong question. It would be like asking, "Why do males have nipples?" The correct question is, "Why do females have nipples?" The answer is that febales need them to nurture their babies, and amles and females are built on the same architectural frame. It was simply easier for nature to construct males with worthless nipples rather than reconfigure the underlying genetic architecture.

Panta Pei: Ha ha ha ha! Too funny.

scigirl

Oh, and the YEC answer:
1. Goddidit that way
2. Goddidit that way
3. Goddidit that way

sheesh, that was easy!

Blinn · 06-09-2002, 12:34 PM

Quote:

Originally posted by Koiyotnik:
Correct me if I'm wrong, but the reason males have nipples is because during the development of a fetus in the womb, it is for a time gender non-specific.

At a certain period in the pregnancy, the gender is determined, and the fetus begins to develop specific organs.

Essentially, the male and female reproductive organs are the same things (to a certain stage), though developed differently. (ie, the clitoris and the head of a penis are pretty much the same thing.)

The same reasoning could be said for nipples, I suppose.

Then again, this is just me trying to remember Grade Eleven health classes.

And the development of the internal genitalia is similar. At 8 to 10 weeks, an embryo has neutral gonads with two duct systems (Mullerian and Wolffian) joined at the lower end. At the 13th week, gonads differentiate in response to germ cell invasion.
If the genotype is XX, then no hormones are released; Mullerian ducts develop into oviducts (Fallopian tubes), uterus, and upper portion of vagina; Wolffian ducts disappear without stimulation from testosterone.
If the genotype is XY, the gonads produce Mullerian duct inhibitor (MDI) which causes the Mullerian ducts to disappear; the gonads will produce testosterone which causes Wolffian ducts to develop into sperm collecting apparatus - epididymis, sperm duct (vas deferens), and seminal vesicle; conversion of testosterone to dyhydrotestosterone (DHT) causes development of prostate gland. (Edited to clarify that...) Estrogen from the ovaries produced at the onset of puberty stimulates breast development.

[ June 09, 2002: Message edited by: Zetek ]

The Other Michael · 06-09-2002, 12:58 PM

I thought men had nipples to add some novelty to an otherwise uninteresting expanse of skin.

But then that raises the question of why the number of nipples doesn't vary with the area of the chest skin.

cheers,
Michael

Blinn · 06-09-2002, 01:34 PM

So is the saying "You're as worthless on tits on a boar hog," considered an idiom or is there a more appropriate linguistic term?

[ June 09, 2002: Message edited by: Zetek ]

Zack · 06-09-2002, 02:31 PM

Men have nipples in order to give us something else to play with.

(straight guys: you know this too)

Bill · 06-09-2002, 04:53 PM

Quote:

Originally posted by Daydreamer:
Why are male gentalia place in outside our bodies and in front of us, where they are so vulnerable?

My recollection on this point is that it takes a certain temperature range for sperm to develop properly. That temperature range cannot be obtained inside the body. So, the testicles must be located outside of the body. The other primary male organ might have been sequestered when sexual arousal was not an issue (it is in some species, like dolphins). But most male mammals are burdened with this external "excess baggage," so I gather its not a problem that is unique to the human species.

== Bill

madmike · 06-09-2002, 09:00 PM

Which vestigial organs are you talking about? I believe advances in the medical and microbiology level have shown that humans don't have any more vestigial organs. Just because YOU don't know what it's for. I bet your significant other can name one of your vestigial organs.

lpetrich · 06-09-2002, 09:31 PM

Quote:

Originally posted by madmike:
Which vestigial organs are you talking about? I believe advances in the medical and microbiology level have shown that humans don't have any more vestigial organs. ...

And what brings to that conclusion, O madmike? Produce your "evidence".

We have legions of vestigial features, though in many cases, those features have functions different from what their structures would suggest.

* Fused bones: skull bones, pelvis (hip equivalent of shoulderblade and collarbone fused with 5 vertebrae)

* Embryonic gill slits (not functional gills!) and circulation

* Embryonic tail

* Coccyx (tail bone)

* Appendix

* Toes

* Brow ridges

* Mitochondria

* Pseudogenes

madmike · 06-09-2002, 10:06 PM

lpetrich

Have you ever picked up a medical journal or taken a human and physiology class since 1965?

I will go over the obvious.

* Fused bones: skull bones, pelvis (hip equivalent of shoulderblade and collarbone fused with 5 vertebrae)

If your skull wasn't fused I could crack you on the head and you would cease to live. Pelvis is set up that way to aid in the delivery of an offspring

* Embryonic gill slits (not functional gills!) and circulation

WE DO NOT HAVE GILLS! The "slits" are not slits at all. They are the first stages of the bones that make up the inner ear. just because they look like slits doesn't mean they are.

* Embryonic tail
The bone structure is formed before the muscle structure has time to fully cover it, it looks like a tail but is actually your vertebrate before it is covered over buy the rest of tissues and muscles of that area
* Coccyx (tail bone)
Try to deficate without a coccyx!!! Have you ever broken yours? This tail bone holds many muscles that aid in excretion.

* Appendix
The appendix plays a large role in the ammune system. This organ is perforated by huge numbers of lymph nodes and tissue. Just because you can live a normal life if they take it out doesn't mean it's not necessary . The human body has a tremendous way of compensating for malfunctioning parts.
* Toes
Really, you don't use yours???? Would you be happier with hoofs, or flippers??? Really what the hell do you mean?

* Mitochondria
You wouldn't be alive without them. This is all the explination that one deserves.

lpetrich · 06-09-2002, 11:56 PM

madmike:
Have you ever picked up a medical journal or taken a human and physiology class since 1965?

First, what's so special about the year 1965?

And I have read plenty of professional-science literature O madmike. Have you? In particular, have you ever read any evolutionary-biology journal or taken a class in that subject?

* Fused bones: skull bones, pelvis (hip equivalent of shoulderblade and collarbone fused with 5 vertebrae)

If your skull wasn't fused I could crack you on the head and you would cease to live. Pelvis is set up that way to aid in the delivery of an offspring

Don't be a fool, madmike. Being fused is a vestigial feature, because the skull could have started off as a single bone.

Also, why give birth through the pelvis's main opening? Why not at the front of the pelvis in C-section-ish fashion? This looks like some rather awkward vestigial figure, the evolutionary equivalent of "it seemed like a bright idea at the time".

* Embryonic gill slits (not functional gills!) and circulation

WE DO NOT HAVE GILLS! The "slits" are not slits at all. They are the first stages of the bones that make up the inner ear. just because they look like slits doesn't mean they are.

They look very much like similar structures in other vertebrate embryos, and in fish, these structures become gills. Also, their blood circulation is appropriate for them being gills -- and as the embryo grows, it gets reorganized for being more suitable for land-animal duty. Complete with one of the gill-arch blood vessels dropping out and the one on the other side becoming the aortic arch.

* Embryonic tail
The bone structure is formed before the muscle structure has time to fully cover it, it looks like a tail but is actually your vertebrate before it is covered over buy the rest of tissues and muscles of that area

A tail, by any other name, is still a tail.

* Coccyx (tail bone)
Try to deficate without a coccyx!!! Have you ever broken yours? This tail bone holds many muscles that aid in excretion.

Madmike, do you realize how stupid this makes you look? If there was no coccyx, then those muscles could easily attach to the pelvis.

* Appendix
The appendix plays a large role in the ammune system. This organ is perforated by huge numbers of lymph nodes and tissue. ...

So what if it does? And why does it look like a shrunken outpouching of the large intestine? Why not something else?

* Toes
Really, you don't use yours???? Would you be happier with hoofs, or flippers??? Really what the hell do you mean?

What I mean is: do our feet really need toes in order to function properly? And why not continuous hinge instead of separate digits?

* Mitochondria
You wouldn't be alive without them. This is all the explination that one deserves.

What is vestigial about them is that they have their own genome and their own DNA->RNA->protein mechanism. Why would they need that when they get many of their proteins from the surrounding cell?

Comparison of their genes and proteins has revealed that they are most closely related to certain bacteria, notably Rickettsia bacteria. So they were once free-living bacteria that had become inhabitants of some other cells, losing many of their genes to their host cells. Which had happened 2 billion years ago, long before any multicelled organisms had existed, let alone our species. To learn more, do a net search for "endosymbiosys".

I note that Madmike had omitted pseudogenes. Hmmm.... could it be that his superior knowledge of physiology does not include awareness of the existence of pseudogenes?

06-09-2002, 01:34 PM	#14
Blinn Veteran Member Join Date: Aug 2001 Location: Ohio, USA Posts: 1,162	So is the saying "You're as worthless on tits on a boar hog," considered an idiom or is there a more appropriate linguistic term? [ June 09, 2002: Message edited by: Zetek ]</p>

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06-09-2002, 12:58 PM	#13
The Other Michael Honorary Member Join Date: Apr 2002 Location: In the fog of San Francisco Posts: 12,631	I thought men had nipples to add some novelty to an otherwise uninteresting expanse of skin. But then that raises the question of why the number of nipples doesn't vary with the area of the chest skin. cheers, Michael

06-09-2002, 02:31 PM	#15
Zack Junior Member Join Date: May 2002 Location: Western Washington Posts: 28	Men have nipples in order to give us something else to play with. (straight guys: you know this too)

06-09-2002, 09:00 PM	#17
madmike Junior Member Join Date: Mar 2002 Location: Pensacola Posts: 7	Which vestigial organs are you talking about? I believe advances in the medical and microbiology level have shown that humans don't have any more vestigial organs. Just because YOU don't know what it's for. I bet your significant other can name one of your vestigial organs.

06-09-2002, 10:06 PM	#19
madmike Junior Member Join Date: Mar 2002 Location: Pensacola Posts: 7	lpetrich Have you ever picked up a medical journal or taken a human and physiology class since 1965? I will go over the obvious. * Fused bones: skull bones, pelvis (hip equivalent of shoulderblade and collarbone fused with 5 vertebrae) If your skull wasn't fused I could crack you on the head and you would cease to live. Pelvis is set up that way to aid in the delivery of an offspring * Embryonic gill slits (not functional gills!) and circulation WE DO NOT HAVE GILLS! The "slits" are not slits at all. They are the first stages of the bones that make up the inner ear. just because they look like slits doesn't mean they are. * Embryonic tail The bone structure is formed before the muscle structure has time to fully cover it, it looks like a tail but is actually your vertebrate before it is covered over buy the rest of tissues and muscles of that area * Coccyx (tail bone) Try to deficate without a coccyx!!! Have you ever broken yours? This tail bone holds many muscles that aid in excretion. * Appendix The appendix plays a large role in the ammune system. This organ is perforated by huge numbers of lymph nodes and tissue. Just because you can live a normal life if they take it out doesn't mean it's not necessary . The human body has a tremendous way of compensating for malfunctioning parts. * Toes Really, you don't use yours???? Would you be happier with hoofs, or flippers??? Really what the hell do you mean? * Mitochondria You wouldn't be alive without them. This is all the explination that one deserves.

06-09-2002, 11:56 PM	#20
lpetrich Contributor Join Date: Jul 2000 Location: Lebanon, OR, USA Posts: 16,829	madmike: Have you ever picked up a medical journal or taken a human and physiology class since 1965? First, what's so special about the year 1965? And I have read plenty of professional-science literature O madmike. Have you? In particular, have you ever read any evolutionary-biology journal or taken a class in that subject? * Fused bones: skull bones, pelvis (hip equivalent of shoulderblade and collarbone fused with 5 vertebrae) If your skull wasn't fused I could crack you on the head and you would cease to live. Pelvis is set up that way to aid in the delivery of an offspring Don't be a fool, madmike. Being fused is a vestigial feature, because the skull could have started off as a single bone. Also, why give birth through the pelvis's main opening? Why not at the front of the pelvis in C-section-ish fashion? This looks like some rather awkward vestigial figure, the evolutionary equivalent of "it seemed like a bright idea at the time". * Embryonic gill slits (not functional gills!) and circulation WE DO NOT HAVE GILLS! The "slits" are not slits at all. They are the first stages of the bones that make up the inner ear. just because they look like slits doesn't mean they are. They look very much like similar structures in other vertebrate embryos, and in fish, these structures become gills. Also, their blood circulation is appropriate for them being gills -- and as the embryo grows, it gets reorganized for being more suitable for land-animal duty. Complete with one of the gill-arch blood vessels dropping out and the one on the other side becoming the aortic arch. * Embryonic tail The bone structure is formed before the muscle structure has time to fully cover it, it looks like a tail but is actually your vertebrate before it is covered over buy the rest of tissues and muscles of that area A tail, by any other name, is still a tail. * Coccyx (tail bone) Try to deficate without a coccyx!!! Have you ever broken yours? This tail bone holds many muscles that aid in excretion. Madmike, do you realize how stupid this makes you look? If there was no coccyx, then those muscles could easily attach to the pelvis. * Appendix The appendix plays a large role in the ammune system. This organ is perforated by huge numbers of lymph nodes and tissue. ... So what if it does? And why does it look like a shrunken outpouching of the large intestine? Why not something else? * Toes Really, you don't use yours???? Would you be happier with hoofs, or flippers??? Really what the hell do you mean? What I mean is: do our feet really need toes in order to function properly? And why not continuous hinge instead of separate digits? * Mitochondria You wouldn't be alive without them. This is all the explination that one deserves. What is vestigial about them is that they have their own genome and their own DNA->RNA->protein mechanism. Why would they need that when they get many of their proteins from the surrounding cell? Comparison of their genes and proteins has revealed that they are most closely related to certain bacteria, notably Rickettsia bacteria. So they were once free-living bacteria that had become inhabitants of some other cells, losing many of their genes to their host cells. Which had happened 2 billion years ago, long before any multicelled organisms had existed, let alone our species. To learn more, do a net search for "endosymbiosys". I note that Madmike had omitted pseudogenes. Hmmm.... could it be that his superior knowledge of physiology does not include awareness of the existence of pseudogenes?

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