First proposed by the Scottish philosopher David Hume, the is-ought problem identifies the fallacy of moving from statements about how the world is to statements about how the world ought to be. We can identify an is-ought fallacy in a grossly simplified argument in favor of the Paleo diet which states that because human beings have eaten certain foods throughout the vast majority of history, modern humans should eat those same foods. Obviously, any convincing argument in favor of the Paleo diet is going to have to do better than that. After all, we generally believe that modern technology improves our overall well-being. A strong argument in favor of the Paleo diet would have to show that 1) human diets have changed in the past century, 2) humans have developed ailments rarely seen in ancestral populations over the same time period, and 3) there is some evidence that staples of our new diet can be linked to these new maladies.
Another example of the is-ought problem appears in biomechanist Katy Bowman’s book Move Your DNA. Bowman points out that orcas in captivity exhibit collapsed dorsal fins, in contrast to the rigid fins of orcas in the wild. Observing that captive orcas are kept in relatively shallow tanks and only swim in counter-clockwise circles, scientists hypothesize that collapsed dorsal fins result from the unnaturally high loads of swimming in the same direction and swimming closer to the surface of the water where gravity has a greater effect. Orcas do not have innate support structures for their dorsal fins, and wild orcas do not need them because their fins are stabilized merely by swimming forward and at great depths. A wild orca’s environment and its movement patterns in its natural habitat keep its fin upright.
On the surface, this fin phenomenon looks like an argument against taking orcas out of the wild. “Just look at those flaccid fins!” you might object. “That’s not natural. That’s not right.” But even granting that the motions and forces of captivity cause collapsed fins, we don’t yet have an argument to move from statements about what is natural to statements about what is right. In short, we have no evidence (at least, not from Bowman) that a collapsed fin is a deleterious condition for an orca. Perhaps orcas are unaware of the state of their dorsal fins; perhaps the shape of the fin causes no particular comfort or discomfort at all. If that is the case, we have no argument against keeping orcas in captivity, at least not if we want to base that argument on fin position.
In Move Your DNA, Bowman uses the anecdote about whales in captivity as an analogy for humans in captivity, that is, modern humans who spend hours sitting in chairs and hunched over computers. But in regards to humans, Bowman signifies her attempt to surmount the is-ought problem with her first sentence of the book: “Who wants to be healthy?” (p. 1). It should come as no surprise that our ancestors, unaccustomed to chairs and cars and paved or tiled surfaces, moved more frequently and with more variety than we do today. In order to sidestep the is-ought problem, Bowman must show that movement patterns are linked to health, and that the way we move (or don’t move) in modern Western society contributes to many of our physical ailments.
She tackles this challenge in the first section of the book, combining considerable anthropological research with her own precise biomechanical insights. Our hunter-gatherer ancestors squatted frequently, sat on the ground, carried loads by hand, and walked a variety of distances and speeds, averaging 2.75 miles per day. Our bodies are designed to handle these positions and movements; in fact, we need to move just to circulate our blood and deliver oxygen and other nutrients to cells throughout our bodies. In a book intended for the lay reader, Bowman touches on scientific evidence throughout this section but doesn’t dwell on it, always circling back to her underlying message that movement matters. Resources are not cited in the text, but can be found at the end of the book, organized by chapter and author.
Regarding the is-ought problem, Bowman argues that 1) we move very differently than our ancestors throughout our lives, 2) our bodies are often ill-equipped to handle normal loads, positions and movements (e.g. you throw your back out helping a friend move or you can’t sit cross-legged on the ground), 3) movement frequency and variety are directly linked to physical health, and 4) we need to move more like our ancestors in order to avoid modern physical ailments. Her argument is not always presented in straightforward fashion and some of it is implicit (for example, if you can’t raise your arms above your head and your shoulders constantly ache, you should start to think those issues might be related). But overall, it is a very strong argument.
The most compelling parts of the book are Bowman’s salvos against commonly accepted modern practices (e.g. clothing babies in diapers and wearing bras) and new trends in the natural movement community (e.g. standing desks). She continually points out how unnatural garments create new loading patterns on the body that influence motor development and tissue health and reminds readers that they should aim to move more, not find new positions in which to remain sedentary. Most of these observations make sense, but they would benefit by reference to specific citations (instead of the lists of references at the end of the book).
From a look at how humans used to move and the importance of movement, Bowman shifts focus to some basic positions and movements like standing, sitting on the ground, walking, hanging and squatting in the second part of the book. Here, her message continues to shift from descriptive to prescriptive. She offers corrective stretches to help modern humans transition their bodies back to proper movement, particularly movement in the constantly varied natural environment. This collection of exercises is certainly thorough, but some more detailed diagrams depicting correct and incorrect positions as well as some guidance on how to incorporate what looks like a lengthy routine into an already busy life would be welcome additions.
That being said, self-motivated readers will still garner a wealth of knowledge from Bowman’s corrective exercises, and from her unique insights interspersed throughout the entire book. Move Your DNA is a fresh and useful addition to the discussion of human movement that succeeds in explaining how proper and regular movement is vital to human health.