It had long been believed that the now-extinct Neanderthals walked differently and had a different posture than modern humans. This was based on comparative anatomical studies between ancient Neanderthal skeletons and human spines dating to the 19th century and beyond. A new study has now turned these beliefs on their head by adjusting the samples used to conduct this comparative analysis.
Understanding the Curvature of Neanderthal and Human Spines
These studies focused on the physical curvature of the spine in each species, and noted clear differences between the two types of hominin. This curvature in the lower back is caused by the wedging, or angling, of the vertebrae (bones) and discs (soft tissue) that comprise the spine.
It seemed that Neanderthal spines were less curved than those of humans, suggesting that evolutionary processes must have led to additional spinal curvature in Homo sapiens. Variations would have had an impact on the way the two species stood and moved, researchers assumed, and those differences would have been obvious if we’d had the chance to travel back in time to watch Neanderthals in action.
But the research that supported such theorizing appears to have been flawed. A new study carried out by a team of U.S.-based anthropologists, which was just published in the journal PNAS Nexus , contradicts these old findings. It turns out that previous assumptions were based on limited and partial information about human spinal development.
The Neanderthal skeletons examined had been recovered during archaeological excavations, and the bones in question were all tens of thousands of years old. But the human skeletons used in these studies all came from contemporary times, which means they included only samples from the modern or post-industrial era. Older human skeletons were not included in this comparative analysis, which proved to be a big mistake.
A classic evolutionary imagery which depicts Neanderthal and human spines as being very different from each other. This idea has now been turned on its head. ( adrenalinapura / Adobe Stock)
New Study Corrects Previous Assumptions
Correcting for this error, the anthropologists involved in the new study compared Neanderthal spines to human spines taken from both pre-industrial and post-industrial times. In total more than 300 human spines were studied, and efforts were made to ensure that all geographical regions were covered in order to make sure the samples were representative.
This change in the research protocols had a huge impact on the results. The anthropologists found notable differences between the shapes of the spines of post-industrial humans and our Neanderthal cousins, but not between the Neanderthals and pre-industrial Homo sapiens .
When the skeletons of ancient humans and Neanderthals were compared, their spines were found to have a similar shape and architecture, with both demonstrating less curvature than the spines of contemporary humans. This outcome suggests that other factors besides evolutionary divergence must account for the differences between Neanderthals and contemporary humans, and between post- and pre-industrial humans as well.
The study argues that after industrialization human spines show signs of increased wedging. They probably suffered from back pain. ( SasinParaksa / Adobe Stock)
The Industrial Lifestyle is a Pain in the … Back
In addition to upending previous ideas about human evolution, these new and surprising results may shed light on why modern humans suffer from so many serious back ailments. “Neanderthals are not distinct from modern humans in lumbar wedging and therefore likely possessed curved lower backs like we do,” explained study leader Scott Williams, an associate professor of anthropology at New York University, in a New York University press release.
“However, over time, specifically after the onset of industrialization in the late 19th century, we see increased wedging in the lower back bones of today’s humans—a change that may relate to higher instances of back pain, and other afflictions, in postindustrial societies.”
Genetic changes can cause alterations in anatomical function and structure. But so can environmental variables, and overlooking that fact steered past researchers in the wrong direction when comparing extinct Neanderthal skeletons to those of modern-era humans. “A pre-industrial vs. post-industrial lifestyle is the important factor,” Dr. Williams stated.
With the arrival of industrialization came significant alterations in people’s daily lives and working conditions. As the industrialized economy advanced fewer people spent less time doing physical work outdoors, moving indoors into cramped spaces that restricted mobility and caused a deterioration of people’s physical states.
For instance, furniture became much more common, as desk jobs in administrative, management, and clerical work proliferated. Others would have stayed seated all day performing various types of manual labor involving machines or tools. People in such jobs would spend long hours on chairs or stools, slumped over desks or worktables or twisted into awkward positions and only occasionally getting up to move around.
Factory assembly lines created many challenges as well, as they would have forced workers to perform repetitive tasks that might very well have encouraged less-than-optimum posture. Accompanying these changes was a dramatic increase in the incidence of back pain—a situation that prevails still today.
“Diminished physical activity levels, bad posture, and the use of furniture, among other changes in lifestyle that accompanied industrialization, resulted, over time, in inadequate soft tissue structures to support lumbar lordosis during development,” Williams said, explaining how back issues would have developed. “To compensate, our lower-back bones have taken on more wedging than our pre-industrial and Neanderthal predecessors, potentially contributing to the frequency of lower back pain we find in post-industrial societies.”
Vertebrae from Neanderthal and human spines. (Williams et. al / PNAS Nexus )
The Environment Emerges Triumphant
Pre- and post-industrial humans and Neanderthals might have all demonstrated relatively uniform posture, whether moving or standing, when observed from a distance. But inside the body contemporary humans are suffering from skeletal deformation, as a response to unhealthy lifestyle changes that leave us vulnerable to chronic back pain.
“Past research has shown that higher rates of low back pain are associated with urban areas and especially in ‘enclosed workshop’ settings where employees maintain a tedious or painful posture at work, such as constantly sitting on stools in a forward leaning position,” Williams said, confirming the connection between post-industrial working conditions, poor spinal development, and back problems.
It seems scientists involved in past comparative anatomy studies between Neanderthals and modern humans were unaware that this research existed. And so they concluded that increased human spine curvature (in comparison to our cousins the Neanderthals) was the result of evolution, and that Neanderthals had not been impacted by the same evolutionary pressures. This conclusion has now been shown to be false. In the ongoing heredity vs. environment debate, we can put this one in the win column for the environment.
Top image: Neanderthal spine (bottom) and post-industrial modern human spines (top) depicting differences in wedging and curvature of the lower back. Source: Scott Williams / NYU’s Department of Anthropology
By Nathan Falde