Are Human Feet Poorly Designed?

A mechanical engineer takes on a physiologist.

The foot is a masterpiece of engineering.

—Leonardo Da Vinci

The Strength of Feet

I have spent precious little time contemplating my feet. I’m flatfooted so I don’t love walking around without shoes, and I rub them from time to time when they get sore, but besides that, they’re very low on my daily list of priorities. Like many things in our lives that work so efficiently (until they break), we are hardly aware of them. But I have recently learned that the design of this critical body part is a mechanical wonder that combines strength, flexibility, and durability—all in a very small space. My feet, I hardly knew you!

However, not everyone agrees that the foot - or any other part of the body - is particularly well designed or, in fact, that they were “designed” at all. Classical Darwinian theory suggests that variation (and later mutation) combined with natural selection is the dynamic responsible for all of the structures of the world’s species, including humans. Given this axiom - that blind forces did the “designing” through small, successive changes - there is no particular reason to suppose a body part should work particularly well. “Why,” they might ask, “can we not hear as well as dogs or live much longer?” “Why do our eyes have blind spots?” “If there is such a great designer, why isn’t the design much better?”

Due to these initial assumptions (and speaking of blind spots), it’s possible to mistake brilliant functionality for total junk. For instance, the assumption of meaningless or outdated body parts led scientists to conclude that the appendix is just a “vestigial structure” of some older version of humans that evolution has not yet weeded out. As such, no one thought much about cutting it right out if it became inflamed. At this point, however, it is now believed to play an important role in maintaining the immune system.

It’s In the Details

And this brings us to our feet. Are they more worthy of our admiration or our scorn? In his 2018 book “Human Errors: a Panorama of Our Glitches, From Pointless Bones to Broken Genes,” Dr. Nathan Lents asserts that “humans have way too many bones” and that “the ankle contains seven bones, most of them pointless.” Dr. Lents has his Ph.D. in physiological Sciences but appears to have missed some of the critical functionality of these “pointless” bones and how they are cleverly coordinated to afford human beings an extraordinary range of motion.

Dr. Stuart Burgess is one of the top mechanical engineers in the UK. He has been doing biomechanics research at Cambridge for the last 30 years, and his labs focus on knees, hands, and ankles. Unlike Dr. Lents, he views human joints as da Vinci did - as a masterpiece of design that provides feet with functionality, efficiency, compactness, and endurance. Think of the forces that the feet of marathoners have to contend with, or the Olympic weight-lifter, or the crazy angles into which professional Tennis players wedge their feet. With all that we put them through, why don’t these bones routinely shatter or dislocate?

Dr. Burgess explains that it is specifically the many bones in the foot that gives it its strength and flexibility. If there were only one bone in place of the five in the middle of the foot, our balance would be hopelessly compromised, and the foot would have a significantly reduced capacity to withstand pressure. The five functionalities he identifies—flexion, pronation, flexibility, strength, and balance are all only due to the ingenious multi-bone design. You can see his whole fascinating presentation on the topic here.

Axioms are everything. Where one chooses to start an exploration into any given topic will perforce color how the outcome is viewed. Some people will look (or want to look) at a natural artifact like a foot and think it’s a work of masterful brilliance, and some just the opposite. That said, I believe Dr. Burgess makes the more compelling case. It looks designed to me (and is something to be thankful for). What do you think?