Freethought & Rationalism Archive

lpetrich · 06-01-2002, 05:03 PM

A spiderweb might at first thought indicate great intelligence on the part of spiders; iI magine one of the ID guys looking at one and saying "What specified complexity!"

However, <a href="http://www.daimi.au.dk/~krink/" target="_blank">Thiemo Krink</a> has done some <a href="http://www.daimi.au.dk/~krink/online_papers/JTB97_Analysing_Webs.pdf" target="_blank">interesting work</a> that shows that spiders can build complicated-looking webs using some very simple rules for where to spin their silk strands. And in that work, TK improved the rule parameters by using genetic-algorithm techniques -- essentially evolution by natural selection.

And one may be able to reconstruct the evolution of web building by looking at what different spider species do with their silk; there are some species that do not spin webs at all, and some that catch their prey with the help of silk draglines or simpler sorts of webs..

I was inspired to think about this by a topic in Science and Skepticism on animal intelligence. It had reminded me of a documentary I had once seen on that subject. The 19th-cy. biologist Romanes had attributed a lot of animal behavior to something like intelligent design on the animals' part, but experiments have shown otherwise in many cases. The documentary showed a circle of tent caterpillars faithfully following a circular silk strand, and it mentioned that beavers will try to build a dam at a speaker playing the sound of rushing water, piling up sticks and mud (PubMed had nothing, and I don't have access to BIOSIS or some similar abstracts database, so I could not check out that claim in the primary literature).

Another example is how ethologist Konrad Lorenz would convince some geese that he was his mother, by being near them when they hatched; <a href="http://www.epub.org.br/cm/n14/experimento/lorenz/index-lorenz.html" target="_blank">this page</a> has some nice pictures of him with his geese and of some recent repeats of his experiments.

There are numerous other such examples of "Fixed Action Patterns" or stereotyped behavior patterns in the animal kingdom; most of the animal kingdom is very short on brains, and genetically-programmed FAP's are a convenient shortcut.

Likewise, most learning is similarly stereotyped; it is almost always conditioned, whether in classical Pavlovian fashion or in operant fashion. "Insight learning", where the learner appears to acquire some insight as to what is to be done, is rare, though it has been well-documented in chimpanzees. In Kohler's classic experiments, chimps could stack crates and wield poles to get to out-of-reach bananas; use of these items may qualify as a form of "intelligent design".

So our species may not be alone in the capability of doing intelligent design, though that capability is rare -- and is most notably apparent in the species closest to our species, the chimpanzees.

In all these examples, whether something was intelligently designed was worked out by studying the "designers" and attempting to work out how they were doing the "designing".

This may explain why the "Intelligent Design" movement seems to have a "I know it when I see it" approach to recognizing "specified complexity" -- the IDers do not seem to have a real strategy for recognizing design.

notto · 06-01-2002, 06:33 PM

"Cell-making instinct of the Hive-Bee. I will not here enter on minute details on this subject, but will merely give an outline of the conclusions at which I have arrived. He must be a dull man who can examine the exquisite structure of a comb, so beautifully adapted to its end, without enthusiastic admiration. We hear from mathematicians that bees have practically solved a recondite problem, and have made their cells of the proper shape to hold the greatest possible amount of honey, with the least possible consumption of previous wax in their construction. It has been remarked that a skilful workman, with fitting tools and measures, would find it very difficult to make cells of wax of the true form, though this is perfectly effected by a crowd of bees working in a dark hive. Grant whatever instincts you please, and it seems at first quite inconceivable how they can make all the necessary angles and planes, or even perceive when they are correctly made. But the difficulty is not nearly so great as it at first appears: all this beautiful work can be shown, I think, to follow from a few very simple instincts.

The Origin of Species
Chapter 7: Instinct
by Charles Darwin

<a href="http://www.talkorigins.org/faqs/origin/chapter7.html" target="_blank">http://www.talkorigins.org/faqs/origin/chapter7.html</a>

Duvenoy · 06-02-2002, 06:42 AM

Thanks for an excellent article on orb weavers. Here�s another, pretty general on spiders:

It is fun though to observe how characteristics and traits have evolved in animals. Lets take a closer look at the uses by spiders of silk in hunting. Spiders like Tarantulas live in holes in the ground, in these holes silk is used to line the walls and to make the spiders home more pleasant to live in, however tarantulas do not use silk to help them hunt or to wrap their prey in except in as much as some species may use some silk lines outside their door help them know when prey is there and help them get back into the hole quickly. Within the Labidognatha there is a great range of ways that spiders use their silk to hunt. A simple usage of silk in hunting is exhibited by Segestria florentina Segestria also lives in a silk lined hole, but as well as in her hole she has triplines of silk that run a short way out from her hole, when an insect touches one of these lines and causes it to vibrate Segestria runs out of her hole and grabs them in her chelicera and then rushes back to her hole to eat her dinner. The house spider Tegenaria domestica hunts in a similar manner except that instead of a few triplines she has a whole messy sheet of web in front of her door, any insect that lands on this is reguarded as dinner. There are many more interesting uses of silk from the horizontal sheet and tangle webs used by many spiders that you can see in any wood, garden or grassland. To fascinating examples like Dinopus guatemalensis the Net Casting Spider which makes a net of silk web and then hangs upside down waiting for something to pass so that it can drop its net on to it. Or the Bolas Spiders like the American Mastophora sp. which emits a pheromone which mimics the sex attractant used by certain moths of the genus Spodoptera (Army Worms). Males that attracted to the false pheromone are then caught by the spider swinging a stand of silk with a sticky blob on the end at the moth and then hauling it in.

<a href="http://www.earthlife.net/insects/webevolv.html" target="_blank">http://www.earthlife.net/insects/webevolv.html</a>

Jumping Spiders are, as far as I�m concerned, among the most charming creatures in the world. Here�s a good site with lots of pics. Only obliquely mentioned in the article is it�s web. In the field while looking for something else and becoming distracted by a jumper, I�ve twice observed them to jump at an insect on the wing, snag it, and swing back to the vertical plant stem like a trapeze artist on it�s strand of web.

<a href="http://www.xs4all.nl/~ednieuw/Spiders/Salticidae/Salticidae.htm" target="_blank">http://www.xs4all.nl/~ednieuw/Spiders/Salticidae/Salticidae.htm</a>

Spiders have other uses for the web other than catching prey. Tarantulas, when they molt, will first spin a comfortable bed for themselves to lie on during the process. Burrowing spiders such as trapdoor species line their tunnels and construct their doors of debris held together with silk.

Hatchling spiders will climb to a high spot and on a windy day, release a long strand of web, then let go to float away like a dandelion seed, often colonizing new territories.

Spiders were the first arthropod to re-colonize the devastation left by the eruption of Mt. St. Helene, eating mostly each other until prey species began to move in.

Spiders are so well adapted to the world around them and yet so bizaar that I find them an argument against ID. Why should a supreme being go to all that trouble just to amuse me with the antics of a jumping spider?

d

Dr.GH · 06-02-2002, 10:29 AM

lpetrich,

I think you make a very interesting point. What would Dembski's explanitory filter make of the spider's web.

David Bowden · 06-02-2002, 10:52 AM

Fascinating posts, all. And I love the Darwin quote:

Quote:

Originally posted by notto:
But the difficulty is not nearly so great as it at first appears: all this beautiful work can be shown, I think, to follow from a few very simple instincts.[/b]

This next is off-topic, but I just noticed that the online edition of Origin is different from my copy, and was wondering if someone might be able to clear this up for me:

Chapter 7: ("Instinct", in the talkorigins version) is "Miscellaneous Objections to the Theory of Natural Selection" in my copy, followed by Chapter 8: "Instinct", and so on to the end, where the titles are identical but the numbering is off by one. The chapter on objections appears to have been left out of the online version. Are these perhaps different editions, or did the talkorigins folks lose a chapter in transcribing it, or is there some other explanation?

(If it helps, the edition I own is part of the Britannica Great Books set, 2nd ed, vol 49, and is bound together with The Descent of Man.)

Thanks,
-Wanderer

Dr.GH · 06-02-2002, 11:18 AM

Quote:

This next is off-topic, but I just noticed that the online edition of Origin is different from my copy, and was wondering if someone might be able to clear this up for me:

There are 8? editions. Darwin kept revising in response to critics.

lpetrich · 06-02-2002, 11:52 AM

(Of the Origin of Species...)

Quote:

Originally posted by Dr.GH:

There are 8? editions. Darwin kept revising in response to critics.

I wonder if anyone has collected those editions and pointed out differences from edition to edition.

Huginn · 06-02-2002, 11:57 AM

Interestingly orb webs seem to have actually evolved twice. Most orb weaving spiders belong to the familiy Araneidae and produce silk covered in gluey beads that trap insects. However, in the family Uloboridae (not closely related to the Araneidae) some members build webs that look very much like orb webs but trap insects with fluffy silk that works a bit like velcro.

Two similar yet very different approaches to the same thing. Not consistent with the idea of an intelligent designer. More of a bumbling, forgetful, absent minded, insane designer.

Below: Uloborus plumipes in its orb web.

[ June 02, 2002: Message edited by: Huginn ]

Dr.GH · 06-02-2002, 12:45 PM

I just checked, and there were 6 editions by Darwin. I would not be surprised if there were many studies of how Darwin responded to critics. I am far from a Darwin scholar, though. You might find something here:<a href="http://pub42.bravenet.com/sitering/nav.php?usernum=3560910512&action=list&siteid=3649 7" target="_blank">Charles Darwin web ring</a>

[ June 02, 2002: Message edited by: Dr.GH ]

lpetrich · 06-02-2002, 01:03 PM

Quote:

Originally posted by Dr.GH:
lpetrich,

I think you make a very interesting point. What would Dembski's explanitory filter make of the spider's web.

I'm flattered. And I kick myself for not thinking of this issue earlier. Maybe I should write a full-scale article on missteps in diagnosing intelligent design, covering both animal-behavior and planet-feature examples (craters of Moon, canals of Mars).

Animal intelligent design had actually been proposed in detail by at least one reputable biologist. Back in the 19th cy., George Romanes published a book Animal Intelligence (1888), in which he claimed to have seen an abundance of intelligent design in animal behavior, as exemplified in the numerous anecdotes he had collected.

As a result, his work became mainly known as an example of how not to do animal-behavior research, and those claiming examples of intelligent-design behavior have become much more cautious.

06-01-2002, 05:03 PM	#1
lpetrich Contributor Join Date: Jul 2000 Location: Lebanon, OR, USA Posts: 16,829	Spiderwebs: Intelligently Designed? A spiderweb might at first thought indicate great intelligence on the part of spiders; iI magine one of the ID guys looking at one and saying "What specified complexity!" However, <a href="http://www.daimi.au.dk/~krink/" target="_blank">Thiemo Krink</a> has done some <a href="http://www.daimi.au.dk/~krink/online_papers/JTB97_Analysing_Webs.pdf" target="_blank">interesting work</a> that shows that spiders can build complicated-looking webs using some very simple rules for where to spin their silk strands. And in that work, TK improved the rule parameters by using genetic-algorithm techniques -- essentially evolution by natural selection. And one may be able to reconstruct the evolution of web building by looking at what different spider species do with their silk; there are some species that do not spin webs at all, and some that catch their prey with the help of silk draglines or simpler sorts of webs.. I was inspired to think about this by a topic in Science and Skepticism on animal intelligence. It had reminded me of a documentary I had once seen on that subject. The 19th-cy. biologist Romanes had attributed a lot of animal behavior to something like intelligent design on the animals' part, but experiments have shown otherwise in many cases. The documentary showed a circle of tent caterpillars faithfully following a circular silk strand, and it mentioned that beavers will try to build a dam at a speaker playing the sound of rushing water, piling up sticks and mud (PubMed had nothing, and I don't have access to BIOSIS or some similar abstracts database, so I could not check out that claim in the primary literature). Another example is how ethologist Konrad Lorenz would convince some geese that he was his mother, by being near them when they hatched; <a href="http://www.epub.org.br/cm/n14/experimento/lorenz/index-lorenz.html" target="_blank">this page</a> has some nice pictures of him with his geese and of some recent repeats of his experiments. There are numerous other such examples of "Fixed Action Patterns" or stereotyped behavior patterns in the animal kingdom; most of the animal kingdom is very short on brains, and genetically-programmed FAP's are a convenient shortcut. Likewise, most learning is similarly stereotyped; it is almost always conditioned, whether in classical Pavlovian fashion or in operant fashion. "Insight learning", where the learner appears to acquire some insight as to what is to be done, is rare, though it has been well-documented in chimpanzees. In Kohler's classic experiments, chimps could stack crates and wield poles to get to out-of-reach bananas; use of these items may qualify as a form of "intelligent design". So our species may not be alone in the capability of doing intelligent design, though that capability is rare -- and is most notably apparent in the species closest to our species, the chimpanzees. In all these examples, whether something was intelligently designed was worked out by studying the "designers" and attempting to work out how they were doing the "designing". This may explain why the "Intelligent Design" movement seems to have a "I know it when I see it" approach to recognizing "specified complexity" -- the IDers do not seem to have a real strategy for recognizing design.

06-02-2002, 11:57 AM	#8
Huginn Veteran Member Join Date: May 2001 Location: Lincoln, England Posts: 1,499	Interestingly orb webs seem to have actually evolved twice. Most orb weaving spiders belong to the familiy Araneidae and produce silk covered in gluey beads that trap insects. However, in the family Uloboridae (not closely related to the Araneidae) some members build webs that look very much like orb webs but trap insects with fluffy silk that works a bit like velcro. Two similar yet very different approaches to the same thing. Not consistent with the idea of an intelligent designer. More of a bumbling, forgetful, absent minded, insane designer. Below: Uloborus plumipes in its orb web. [ June 02, 2002: Message edited by: Huginn ]</p>

06-02-2002, 12:45 PM	#9
Dr.GH Veteran Member Join Date: Jul 2001 Location: Dana Point, Ca, USA Posts: 2,115	I just checked, and there were 6 editions by Darwin. I would not be surprised if there were many studies of how Darwin responded to critics. I am far from a Darwin scholar, though. You might find something here:<a href="http://pub42.bravenet.com/sitering/nav.php?usernum=3560910512&action=list&siteid=3649 7" target="_blank">Charles Darwin web ring</a> [ June 02, 2002: Message edited by: Dr.GH ]</p>

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06-01-2002, 06:33 PM	#2
notto Regular Member Join Date: Jul 2001 Location: Minneapolis, MN US Posts: 133	"Cell-making instinct of the Hive-Bee. I will not here enter on minute details on this subject, but will merely give an outline of the conclusions at which I have arrived. He must be a dull man who can examine the exquisite structure of a comb, so beautifully adapted to its end, without enthusiastic admiration. We hear from mathematicians that bees have practically solved a recondite problem, and have made their cells of the proper shape to hold the greatest possible amount of honey, with the least possible consumption of previous wax in their construction. It has been remarked that a skilful workman, with fitting tools and measures, would find it very difficult to make cells of wax of the true form, though this is perfectly effected by a crowd of bees working in a dark hive. Grant whatever instincts you please, and it seems at first quite inconceivable how they can make all the necessary angles and planes, or even perceive when they are correctly made. But the difficulty is not nearly so great as it at first appears: all this beautiful work can be shown, I think, to follow from a few very simple instincts. The Origin of Species Chapter 7: Instinct by Charles Darwin <a href="http://www.talkorigins.org/faqs/origin/chapter7.html" target="_blank">http://www.talkorigins.org/faqs/origin/chapter7.html</a>

06-02-2002, 06:42 AM	#3
Duvenoy Veteran Member Join Date: May 2002 Location: Just another hick from the sticks. Posts: 1,108	Thanks for an excellent article on orb weavers. Here�s another, pretty general on spiders: It is fun though to observe how characteristics and traits have evolved in animals. Lets take a closer look at the uses by spiders of silk in hunting. Spiders like Tarantulas live in holes in the ground, in these holes silk is used to line the walls and to make the spiders home more pleasant to live in, however tarantulas do not use silk to help them hunt or to wrap their prey in except in as much as some species may use some silk lines outside their door help them know when prey is there and help them get back into the hole quickly. Within the Labidognatha there is a great range of ways that spiders use their silk to hunt. A simple usage of silk in hunting is exhibited by Segestria florentina Segestria also lives in a silk lined hole, but as well as in her hole she has triplines of silk that run a short way out from her hole, when an insect touches one of these lines and causes it to vibrate Segestria runs out of her hole and grabs them in her chelicera and then rushes back to her hole to eat her dinner. The house spider Tegenaria domestica hunts in a similar manner except that instead of a few triplines she has a whole messy sheet of web in front of her door, any insect that lands on this is reguarded as dinner. There are many more interesting uses of silk from the horizontal sheet and tangle webs used by many spiders that you can see in any wood, garden or grassland. To fascinating examples like Dinopus guatemalensis the Net Casting Spider which makes a net of silk web and then hangs upside down waiting for something to pass so that it can drop its net on to it. Or the Bolas Spiders like the American Mastophora sp. which emits a pheromone which mimics the sex attractant used by certain moths of the genus Spodoptera (Army Worms). Males that attracted to the false pheromone are then caught by the spider swinging a stand of silk with a sticky blob on the end at the moth and then hauling it in. <a href="http://www.earthlife.net/insects/webevolv.html" target="_blank">http://www.earthlife.net/insects/webevolv.html</a> Jumping Spiders are, as far as I�m concerned, among the most charming creatures in the world. Here�s a good site with lots of pics. Only obliquely mentioned in the article is it�s web. In the field while looking for something else and becoming distracted by a jumper, I�ve twice observed them to jump at an insect on the wing, snag it, and swing back to the vertical plant stem like a trapeze artist on it�s strand of web. <a href="http://www.xs4all.nl/~ednieuw/Spiders/Salticidae/Salticidae.htm" target="_blank">http://www.xs4all.nl/~ednieuw/Spiders/Salticidae/Salticidae.htm</a> Spiders have other uses for the web other than catching prey. Tarantulas, when they molt, will first spin a comfortable bed for themselves to lie on during the process. Burrowing spiders such as trapdoor species line their tunnels and construct their doors of debris held together with silk. Hatchling spiders will climb to a high spot and on a windy day, release a long strand of web, then let go to float away like a dandelion seed, often colonizing new territories. Spiders were the first arthropod to re-colonize the devastation left by the eruption of Mt. St. Helene, eating mostly each other until prey species began to move in. Spiders are so well adapted to the world around them and yet so bizaar that I find them an argument against ID. Why should a supreme being go to all that trouble just to amuse me with the antics of a jumping spider? d

06-02-2002, 10:29 AM	#4
Dr.GH Veteran Member Join Date: Jul 2001 Location: Dana Point, Ca, USA Posts: 2,115	lpetrich, I think you make a very interesting point. What would Dembski's explanitory filter make of the spider's web.

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