If Evolution is to Blame for Back Pain, Why Do We Even Bother?
One day in the spring of my final semester in college I was in a hurry to check my mail between classes. I started running from the conservatory to the mailroom and after barely half a block, had to stop because my lower back hurt. I am tall and slim, much like my dad. When I was growing up, he suffered from periods of lower back pain, so even though I wasn’t particularly active or fit in college, I didn’t think, “Boy, I need to get in shape.” I thought instead, “Well, I guess it’s my build.”
This way of thinking about pain and discomfort is pretty common: my problem isn’t because of how I do things, but because of who I am. When it comes to back pain, this way of thinking has gotten a boost from some evolutionary biologists. They argue that evolution is to blame for back pain.
I’m glad I didn’t know about this line of thinking back in college. If I had, I wouldn’t have just thought: “My back hurts because of my build.” I would have thought, “My back hurts because I’m human.”
What do evolutionary biologists mean when they say that evolution is to blame for back pain?
In popular culture, it’s common to think of evolution as a perfecting process, where our species just keeps getting better and better all the time. But evolution—at least the natural selection kind—is a blind process. Species don’t get better or worse: they adapt to what is. When the environment changes, species either evolve over time to fit it or don’t. Most importantly, new adaptations in a species are constrained by what has come before.
For example, in the recent Cosmos series, Neil deGrasse Tyson explains that eyes originally evolved in water. When animals emerged on land some 375 million years ago, evolution couldn’t start over and “design” eyes for the land. Terrestrial eyes had to evolve from aquatic eyes: and so humans, to give one example, can’t focus on something that is held up right in front of our face. Who knew?
Such constraints on evolution explain the origins of back pain in humans. Our primate ancestors were quadrupeds. Our upright stance and bipedal locomotion are recent adaptations. There just hasn’t been enough time for our backs to have adapted to being upright.
Bruce Latimer, an anthropologist and anatomist at Case Western University, makes this argument to LiveScience. "We're the only mammals that spontaneously fracture vertebra," he says, comparing the spine to a stack of cups and saucers (the cups are the vertebrae and the saucers are the intervertebral disks). He continues:
Then take a book like a dictionary and put it on top. This is the head. If you are really careful, you can balance it — otherwise there's a lot of porcelain on the ground… Then imagine taking this and putting in all the curves that you naturally have in the spine. I could give you all the duct tape in the world, and you still couldn't possibly balance it.
Latimer is featured on Neil Shubin's wonderful PBS series Your Inner Fish. (It is currently streaming on Netflix.) PBS has made a three minute clip featuring Latimer available on youtube:
If our backs are an "engineering nightmare" (strong words!), does this mean we can’t do anything about back pain? If my Alexander students experience relief from back pain in their lessons, are they just deluding themselves?
In his 2013 book, The Story of the Human Body: Evolution, Health, and Disease, Harvard evolutionary biologist Daniel Lieberman suggests that back pain might not be as inevitable as it seems.
Bipedalism first evolved some 6 million years ago, when our hominid ancestors, Ardipithecus and Australopithecus, first stood upright. Approximately 2 million years ago, the earliest human-like hunter-gatherers emerged, including Homo erectus. Modern humans, Homo sapiens, evolved some 200,000 years ago. Lieberman notes that there are important anatomical differences in the spines of Homo sapiens and Homo erectus, specifically one less lumbar vertebra in Homo sapiens, which implies that there was evolutionary pressure selecting for stronger spines in modern humans.
To Lieberman, two predominantly cultural changes help explain the high incidence of modern back pain: the agricultural revolution, 11,000 years ago, and the industrial revolution, some 200 years ago. Lieberman argues that back pain is a “mismatch disease” that results when our evolved adaptations fail to match the demands of our modern, cultural environment. Our hunter-gatherer ancestor’s lives were neither as rigorous as early farmers nor as sedentary as our contemporary lifestyle:
No one has yet quantified the incidence of lower back pain among hunter-gatherers, but foragers rarely sit in chairs, they never sleep on soft mattresses, they often walk while carrying moderate loads, and they also dig, climb, prepare food, and run. They also don’t engage in hours of strenuous work such as hoeing or lifting that repetitively load the back. In other words, hunter-gatherers use their backs moderately—neither as intensively as subsistence farmers nor as minimally as sedentary office workers…
He refers readers to Michael Adams' model of lower back pain risk, then continues:
A healthy back requires an appropriate balance between how much you use your back and how well your back functions. A normal, fit back needs to have a considerable degree of flexibility, strength, and endurance, as well as some degree of coordination and balance. Since people who are mostly sitters tend to have weak and inflexible backs, they are more likely to experience muscle strains, torn ligaments, stressed joints, bulging disks, and other causes of pain if and when they subject their backs to unusual, stressful movements.
Lieberman’s account fits with my experience of back pain at the end of college. Like many college-aged Americans, I had been sitting everyday for hours upon a time for a decade and a half. When I sat in class I leaned back with my weight resting on my tail bone and my lower spine in a c-curve. Yes, my back hurt, but not enough to send me to a doctor. Even so, years later, Joan Murray (the co-director of the Alexander Technique Center Urbana where I trained as an Alexander teacher) would tell me that when we met, my lumbar spine was almost kyphotic (that is, the normal curve of the lower back had been reversed).
First in my Alexander Technique lessons with Carol McCullough and later during my training with the Murrays, I re-learned my basic coordination. In the process, my lower back strengthened and my shoulders broadened. I developed greater comfort in a wider range of positions. I still remember the excitement when I developed enough mobility in my hips and knees and length in my back to squat with my heels on the ground. And the lower back pain went away. I’m more comfortable in my body now as I approach forty than I was at twenty-two, about to graduate from college.
The process wasn’t magic. I relearned how to move and gradually reversed a condition brought about by neglect. And my renewed coordination requires maintenance. But since I make my living from teaching the Alexander Technique and performing on the violin, I'm not tied to a chair the way I was in school. That said, certain situations are more challenging than others. As I learned the hard way, when I’m performing eight shows a week as a violinist in a pit orchestra, I need to make sure that my setup (my chair, my stand, my violin chin rest, etc) makes healthy coordination possible.
The evidence from evolutionary biology does suggest that humans have a risk for back pain. But Bruce Latimer and others overstate their case when they blame evolution for back pain and call the spine an “engineering nightmare.” A risk of pain doesn’t mean that we are destined for pain. If we let it, our modern school and work environments will leave our backs uncoordinated and weak. But we don’t have to become victims of sitting all day. With practice, we sedentary moderns can relearn how to move so that we not only avoid pain, but experience real joy in movement. After all, something else evolved along with our dodgy backs—our minds.
Daniel Lieberman discusses back pain as a mismatch disease in the chapter 12, "The Hidden Dangers of Novelty and Comfort" in The Story of the Human Body. The PBS series Your Inner Fish was originally a book, also by Neil Shubin. The most significant study of the Alexander Technique and back pain was published in the British Medical Journal in 2008 and has been summarized here.