March 10, 2011 | David F. Coppedge

Bone Structure Matches Animal Size

The bigger the animal, the more weight it has to carry.  How can large animals maintain strong bones without making them heavier?  It turns out all animals have struts in their bones called trabeculae, but the larger the animal, the fewer, stronger, and farther apart are the struts.  This new finding is leading to ideas that may improve your car.
    PhysOrg reported on a team from Imperial College London and the Royal Veterinary College that was curious about bone structure in various mammals.  Looking at femurs from 90 different species of mammals, reptiles and birds, they “found that trabeculae, typically found near joints, have different geometry depending on the size of the species.”  This was news to them.  Dr. Michael Doube at Imperial College London said,

“Scientists had not previously known that the structure of trabeculae varied, or scaled up, depending on the size of the animal.  We assumed that trabeculae would be important in supporting the weight of larger creatures such as Asian elephants, which can weigh more than three tonnes.  However, we were surprised to find that animals that have comparatively lighter loads, such as the Etruscan shrew, weighing three grams, also has trabeculae supporting its tiny body.  Our study is helping us to see how the remarkable geometry of trabeculae supports loads in all creatures, no matter how big or small they are.”

In addition, they found that the mass of bone per unit volume was roughly constant in big and small animals, but “the trabeculae in bigger animals were thicker, further apart and less numerous.”
    Moving from observation to explanation, they reasoned that “the big trabecular struts inside the bones of larger animals help to support their heavier load without the need for thicker and denser bones.  Using this structure saves valuable energy in larger animals because they do not have to grow, maintain and carry extra bone tissue around with them.”  Neat idea.  From explanation they moved to application:

The scientists say new structural materials could be developed, which are inspired by geometry inside femurs.  These materials would contain a lattice work of stiff foam that would be reinforced in certain areas, depending on the load being exerted on that particular section.  This type of material could be used in car bodywork, only being reinforced in areas of the car where loads are heaviest.  This could make cars lighter and more fuel efficient.

A capital idea, worthy of stimulus by some entrepreneur.  The scientists delved deeper into their biomimetic hunch and generated 200 computer models of “virtual bones,” giving their open-source code, named BoneJ, to anyone who wants to download it (see BoneJ.org).  About 1500 downloads from 250 institutes and organizations have taken a look at it.  Some of them might have great ideas for lightweight aircraft and automobiles.  Think of the slogans: Tough as an elephant or Built to fly like a bird.
    Now that they understand bone structure better, the team wants to study animal motion and joints “to understand the relationship between how animals walk and bone structure.”  What might come of that?  Understanding bone deformities, for one thing; reconstructing the movement patterns of extinct species, for another.  Their research was published in the Proceedings of the Royal Society B.

Bravo!  Great science with no evolution!  We wish to praise researchers who get the best aspects of science right: observation, explanation, and application to help improve our lives.  Sir Francis Bacon stressed that you will know good science (like good character) by its fruits.  Biomimetics again shows how a design-focused science not only leads to understanding, but to practical benefits.
    We called this “design-focused science” but lest Eugenie and Rick Dawk have a fit, there was no need to mention God, Creator, or religion in this project.  There was, however, an unspoken assumption that animal bones are well designed for what they do (go back and read the quotes for clues).  Was that a science-stopper?  Clearly not.
    It would have been so tempting for the reporter to toss in the Darwin fogma, claiming that animals evolved these amazing optimal solutions by blind chance.  But fogma not only blinds, it stinks.  Who needs useless smoke?  Who needs to hear tall tales, like notions that vastly different animals all converged on the same solution to optimize strength per unit mass?  Clear the air, stick to the observations, and make the theory do something helpful.  Observation – explanation – application: that is classical science.  It worked for Faraday, it’s fair for our-a-day. 

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