Why Biomimicry Beats Engineering: The Case of Spider Silk

Michelle Oyen, a lecturer in the mechanics of biological materials at the University of Cambridge, was probably not intending to put in a plug for intelligent design when she wrote an article for The Conversation about spider silk. But she did.

At first, it appeared she just wanted to dispel an urban myth: "Spider silk is a wonder of nature, but it's not stronger than steel," was her headline. The imitation of spider silk by materials scientists is a classic example of biomimicry.

You must have heard that spider silk is stronger than steel. We all want to believe that there are wonder materials in nature that are far superior to human-made ones. But the problem with statements that sound too good to be true is that they usually are.

Spider silk is not stronger than steel. But that shouldn't stop us from studying it, or from thinking of it as a wonder material. (Emphasis added.)

From there, however, Oyen made a good case for silk as a competitor to steel. Its tensile strength is in the middle of steel's range, she pointed out, whereas its stiffness is much less. But it does outperform steel in one way that makes it attractive to scientists:

Where spider silk seems to beat steel by a large margin is its density, which is almost six times less. On a per-weight basis then, silk starts to look more interesting, with the ratio of strength to density exceeding that of steel.

So in terms of that ratio it's not really wrong to say spider silk is stronger than steel; in fact, further down she directly contradicts the headline: "Spider silk, then, is stronger than steel on a per weight basis," she clarifies.

Strong, flexible, low-density materials are highly attractive to materials engineers. Here's the lead-up to our favorite quote from her article:

Another reason why spider silk is enthuastically studied is because of our interest in mimicking nature through "biomimicry". The key difference between natural materials and man-made ones is not about so much about physical properties. It's about how they are made.

She proceeds to describe how silk is synthesized at room temperature and is environmentally friendly. The ingredients are abundant and readily available. The really choice remark comes as she compares human engineering with natural synthesis:

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