Biomimetics is the design of engineering solutions guided by biological solutions to similar problems. Support materials in biological systems must be tough, flexible, and light. Engineers define a tough material as one that can absorb energy without fracturing. Flexibility is the ability to deform elastically but able to return to the original shape. Size of in both biological and designed system is often determined by many factors. Density of a material becomes important when size cannot be adjusted but lightness is needed. An analysis of several biological materials in terms of these parameters (Wegst and Ashby, Philosophical Magazine, 84, 2004) shows that selection has conserved a bounding value in the product of these parameters; the square root of all of the ratios of toughness and elasticity lie above the dashed line. Patterns like this lead to new science but, in applications to biomimetics, they can also lead to improved technologies.

This image shows a graph. The vertical axis is labeled Toughness and it has tick marks three quarters up the graph beginning with 1, another at 10, and finally the last one at 100. The horizontal axis is labeled 1/Elasticity. It has tick marks three quarters into the bottom line that read 10, 100, 1000. There is a dotted line from the vertical 10  to the horizontal 100. The square root of toughness divided by elasticity is 0.1.
Figure 29.39

Biopolymers like collagen have higher toughness and higher elasticity. Biominerals like enamel have lower toughness but provide rigidity. Some organisms support soft tissue by combining biopolymers and biomaterials. Some rely more on biopolymers. Note that this is a logarithm scale not a linear scale. So that the difference in toughness of keratin and bone is roughly 100 and the difference in rigidity of these to materials is nearly that large.

A. Use this graph to pose questions about the fitness of various biological solutions to the problem of capturing, storing, and using free energy. (Remember that engineers define “toughness” as the ability to absorb energy without fracturing.)

B. Refine this representation by identifying an important property of a biomaterial that is missing and explain its importance in terms of free energy acquisition and use.

C. Explain how these data indicates that the properties of biopolymers will lead to a better biomimetic design of the humanoid robot than is imagined in C3PO of Star Wars fame


An investigation of the evolution of muscle was made by Steinmetz et al. (Nature, 487, 2012), and a sample of data is presented in the following diagram. Below the accepted phylogeny of major groups are rows with families of genes that code for different muscle proteins, including actin and myosin. Shared genes are shown where the cell is darkened. Samples of genes associated with striated and smooth muscle and the Z-disc that terminates the actin-myosin pair are clustered. These are shown in the diagram below, where groups in which muscle cells occur lie within the box whose edges are dashed lines.

This phylogenetic tree shows humans, lancelets, fruit flies, and worms all sharing a node along the lineage named Bilaterians. The Bilaterians share a node with the Cnidarians and Ctenophores. The Cnidarians contain the anemones and hydras. The Ctenophore contains the Jellyfish. All previously mentioned groups are surrounded with a box, labelled Muscle cells. All of the previously mentioned groups share their next node back with sponges. All of these groups share their next node back with fungi. All of these groups share their next node back with plants. A series of muscle subcellular components are shown below the map, as well coloring showing which groups share each component. Humans possess actin, mysosin heavy, myosin light, tropomyosin, Troponin T, Troponin C, alpha actin, Titin, Speg, Calcineurin A, Cap Z, Myopalladin, Murf slash trim, Telethonin. Lancelets possess actin, mysosin heavy, myosin light, tropomyosin, Troponin T, Troponin C, alpha actin, Titin, Calcineurin A, Cap Z, Myopalladin, Murf slash trim. Fruit flies and worms both possess actin, mysosin heavy, myosin light, tropomyosin, paramyosin, Troponin T, Troponin C, alpha actin, Titin, Speg, Calcineurin A, Cap Z, Murf slash trim. Anemones, hydra, jelly, sponge and fungi all possess actin, mysosin heavy, myosin light, tropomyosin, alpha actin, Calcineurin A, Cap Z. Hydras possess. Plant possess mysosin heavy, Calcineurin A, Cap Z.
Figure 29.40

A. Analyze these data in terms of evidence of common ancestry and evidence of the convergent evolution of the muscle cell.

Molecular phylogenetics has provided many insights into the evolution of genes. Because this work is framed by the central organizing principle of evolution it is possible to forget that there are people living today who need evidence that speciation and extinction have occurred throughout Earth’s history.

B. Describe in broad outline a plan using molecular databases for either protein or DNA sequences that you could help those who are in need of evidence construct it.