June 23, 2006 | David F. Coppedge

Science Reporters Spin Spider Web Data Into Evolutionary Program

A spider was found perfectly preserved in amber (fossil tree sap), complete with its web and prey.  It is identical to modern spiders.  Isn’t evolution amazing?
    If you just experienced a software crash, there must be something wrong with your BIOS.  All the news media ran that program just fine.  A patch is available at Darwin’s website, but compatibility is not guaranteed on all platforms.
    Now, the data input: scientists in Spain reported in Science1 finding a piece of amber with the oldest-known evidence of a web-spinning spider.  They remarked, “This elegant, geometric structure is woven with silk fibers that are renowned for their superior mechanical properties.”  It was dated as early Cretaceous (110 million years old), making it the oldest known fossil of a spider apparently able to spin an orb web.  Erik Stokstad in the same issue of Science2 mentioned another find this month by another team of a true orb spinner, also encased in Spanish amber, dated at 115 million years old (see BBC News).  Stokstad commented that it “is remarkably similar to a living spider–showing that the basic, and successful, body plan appeared long ago.”
    One other piece of data provided input for the media-spinning program about this “original worldwide web” as Stokstad whimsically dubbed it.  A second team, also writing in Science,3 studied the genetics of spider web silks.  They replayed the exact same opening lines: “The orb web is a spectacular evolutionary innovation that enables spiders to catch flying prey,” they said, “This elegant, geometric structure is woven with silk fibers that are renowned for their superior mechanical properties.”  Their goal was to resolve a controversy about two groups of orb-spinners, the deinopoids and the araneoids.  Did their web skills evolve from a common ancestor, or independently, as a spectacular example of “convergent evolution”?  This had been an ongoing debate, because the two groups of spiders, while producing similar-looking webs, use different spinnerets, silk types and methods of construction.  The phylogenetic analysis of web-spinning genes by Garb et al. supported the one-origin theory: “Contrary to the view that the orb-web design evolved multiple times, we found that the distribution and phylogeny of silk proteins support a single, ancient origin of the orb web at least 136 million years ago.”  While this removes the puzzle of convergent evolution, it pushes back the origin of this complex trait earlier than previously thought.  Their conclusion was based on comparison of silk-producing genes from living representatives of the two groups, but did not include a theory of how the structural and behavioral differences might have evolved.
    Now that you have the data input, look at how the popular media reported the story:

  • Washington Post led off with “Amber-preserved web shows early spider evolution” and mentioned evolution eight times in its short report.
  • LiveScience mentioned three times that the evolution of web-spinning spiders must have influenced the evolution of flying insects. 
  • National Geographic mentioned the surprise that orb-spinners appeared earlier than thought, back in the time of the dinosaurs, but also brought evolution prominently into the story.  One expert was quoted as saying, “amber such as this latest discovery does preserve vital information on spider evolution.”  (He also mentioned that 500 extinct spiders have been found in amber.)  Another expert explained that the discovery “helps researchers understand the evolution of both spiders and their prey,”  such as spiders “influencing the evolution of flying insects for millions of years.” 
  • Associated Press (see Fox News) focused on the claim that web-spinning evolved only once.  It did, however, describe the exquisite detail in the amber: “The amber, found in Spain, preserved 26 strands of silk, many of them connected to one another.  Glue droplets are visible on the web and prey includes a fly, a mite, a beetle and a wasp.”
  • BBC News spun their web story as all evolution, all the time: “Ancient web spins evolution story,” wrote Helen Briggs; “….The find, described in Science, sheds light on the early evolution of spiders and the insects they fed on.”  Her article included this twist on the word design:  “The fossil web appears to have been designed along the same lines as the round nets woven by modern spiders.”

David Grimaldi (American Museum of Natural History), one of the discoverers of the amber specimen, had this to say about the amount of evolutionary change seen between the 110-million year old spider and modern spiders: “The advanced structure of this fossilised web (from Spain), along with the type of prey that the web caught, indicates that spiders have been fishing insects from the air for a very long time.
    What was observed were modern-looking spiders encased in amber with full web-spinning capabilities.  The phylogenetic study, on the other hand “suggests that the great great ancestors of modern spiders were weaving webs as long ago as 136 million years ago.”

1Peñalver, Grimaldi and Delciòs, “Early Cretaceous Spider Web with Its Prey,” Science, 23 June 2006: Vol. 312. no. 5781, p. 1761, DOI: 10.1126/science.1126628.
2Erik Stokstad, “Spider Genes and Fossils Spin Tales of the Original Worldwide Web,” Science, 23 June 2006: Vol. 312. no. 5781, p. 1730, DOI: 10.1126/science.312.5781.1730a.
3Garb et al., “Silk Genes Support the Single Origin of Orb Webs,” Science, 23 June 2006: Vol. 312. no. 5781, p. 1762, DOI: 10.1126/science.1127946.

We know our readers are more perceptive than the average dupe of mainstream science reporters.  We’re wondering if anyone saw any evolution sneak by through all this advanced, elegant, geometric structure evidenced by these modern-looking spiders and their modern-looking prey.  What?  You haven’t installed the software patch yet?  No wonder.  Just skip the EULA* and go for it.
*Caution: installing this free patch rearranges your memory stacks and forces compliance between conflicting inputs.  Click on the executable name to download: FrontalLobotomy.exe.

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