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This article was originally published as a chapter in the book “Design and Catastrophe: 51 Scientists Explore Evidence in Nature"
Despite all the improvements in science, our solar cells are still extremely inefficient, our medical implants are far from perfect, and our buildings need serious improvement. Where can we find ideas to solve such engineering problems?
Scientists, like poets and painters, have repeatedly turned to nature to search for inspiration since everything in it seems to provide the best outcome with the lowest waste of energy. We call this sort of work biomimetics, or finding inspiration and drawing solutions from nature.
An evolutionist, although not believing that nature has had any design or purpose in mind, will explain this close-to-perfect state of the natural systems as being due to the fact that nature had millions of years to try, improve, and perfect its own mechanisms.
If you read any book about biomimetics, you may be surprised to find that no matter how strongly the author believes in Darwinian evolution, he or she cannot find a better word than “design” to describe nature’s solutions. The word “design” will be used in the textbooks, leading inevitably to the search for a designer.
Spider silk is one of the most fascinating natural structures. Scientists are impressed not only by its structural properties and chemical composition but also by the way spiders control its synthesis.
More than 15 years ago, I wrote a short essay[1] about the design behind the spiderweb and the fascinating material of which it is constituted. The mystery and fascination surrounding this material persist, given its immense potential engineering applications.
Material scientists have been dreaming about a material that would be highly elastic, while stronger than steel and at the same time much lighter. Spider silks are among the strongest and toughest fibers known to science.[2] Using a diverse array of proteins, spiders are able to construct silk fibers that vary tremendously in their mechanical properties, ranging from major ampullate silk with a tensile strength rivaling that of steel to flagelliform silk with a stretchiness approaching that of rubber. A single spider can produce up to seven different types of silk for different uses.[3]
Interestingly, spiders not only know how to change the chemistry of their silk but also the diameter of the thread. Since spiders can dramatically change their own weight and size, they can actively control the diameters of silk threads spun under different environmental conditions, increasing the load-bearing capacity of their draglines.[4]
However, the fundamental question about spider silk is not just the physical-chemical basis of its fascinating properties, but the origin of a sophisticated silk synthesizer inside spiders, able to finetune the desired silk composition and thickness for a variety of applications, including hunting, sheltering, and even flying, or, more precisely, ballooning.[5]
Spiders can be found everywhere in different sizes, colors, and shapes, but all of them have one thing in common: they can produce silk. Similar to the egg and hen question, we have to find an answer as to what came first. Silk is crucial for the survival of the spider. How then, from an evolutionary point of view, did spiders get the ability to produce silk?
Analysis of DNA sequences coding for the C-terminus—also known as the carboxyl-terminus or COOH-terminus—of spider silk proteins from a range of spiders shows a high level of similarity, which is usually interpreted to suggest that many silk C-termini share a common origin and that their physical properties have been highly conserved.[6]
Similarities among different spider silk genes may suggest that they share a common ancestor, but the evolutionary relationships among functional homologues are unclear. It is thought that many of the genes in this family have evolved through gene duplications. Functional relationships are further complicated by the existence of duplicate silk glands, spigots, and spinnerets.[7]
Evolutionists do not have an answer for the origin of spider silk. Silk spinnerets are not found in any postulated evolutionary ancestor, but are only found in certain insects and in spiders, including a Triassic fossil.[8] Different types of spiders have similar silk proteins that have a wide range of physical properties. The degree of similarity among physical properties and predicted secondary structure of silk C-termini suggests that they perform a common function and that changes are likely to be constrained by selection against mutations that disrupt this function.
The very complex and intelligent way spiders control the chemistry of their silk for each specific application, the way spiders determine the diameter of the thread and the geometry of the web, and the fact that such intricate abilities and mechanisms have appeared together in spiders since the beginning of their fossil record supports the idea of a Designer instead of Darwinian evolution.
NOTES
[1] R Montenegro. A teia de aranha. Ciencia das Origens 2003; 6:1–5.
[2] TA Blackledge, J Peréz-Rigueiro, GR Plaza, B Perea, A Navarro, GVGuinea, M Elices. Sequential origin in the high performance properties of orb spider dragline silk. Scientific Reports 2012; 2:782; KN Savage, JM Gosline. The role of proline in the elastic mechanism of hydrated spider silks. Journal of Experimental Biology 2008; 211(12):1948–1957.
[3] L Eisoldt, A Smith, T Scheibel. Decoding the secrets of spider silk. Materials Today 2011; 14(3):80–86.
[4] JO Wolff, A van der Meijden, ME Herberstein. Distinct spinning patterns gain differentiated loading tolerance of silk thread anchorages in spiders with different ecology. Proceedings of the Royal Society B–Biological Sciences 2017; 284:20171124. doi:10.1098/rspb.2017.1124.
[5] M Cho, P Neubauer, C Fahrenson, I Rechenberg. An observational study of ballooning in large spiders: nanoscale multifibers enable large spiders’ soaring flight. PLoS Biology 2018; 16(6):e2004405. doi:10.1371/ journal.pbio.2004405.
[6] RJ Challis, SL Goodacre, GM Hewitt. Evolution of spider silks: Conservation and diversification of C-terminus. Insect Molecular Biology 2006; 15(1):45–56.
[7] O Tokareva, M Jacobsen, M Buehler, J Wong, D Kaplan. Structurefunction-property-design interplay in biopolymers: spider silk. Acta Biomaterialia 2014; 10(4):1612–1626.
[8] PA Selden, JC Gall. A Triassic mygalomorph spider from the northern Vosges, France. Palaeontology 1992; 35:211–235.
Rivelino Montenegro is a scientist and entrepreneur in the biomedical field and founder of many companies in Europe, Canada, and the United States. He holds a degree in Material Science Engineering from the Federal University of Campina Grande and a PhD in Chemistry from the Max Planck Institute of Colloids and Interfaces. He is an expert in nanotechnology, biomimetics, and biomedical engineering. Besides his scientific and business activities, Dr. Montenegro is an author and an internationally sought after speaker for the apparent controversial discrepancies between Bible and science.