Researchers from Simon Fraser University (SFU) in British Columbia believe they may have found a link between back pain and human evolution.
SFU post-doctoral fellow Kimberly Plomp, a biological anthropologist, has been studying ancient bones for disease and injury that provide insight about our ancestors’ health and how they lived, according to a SFU news report written by Diane Luckow.
“Evidence of injury and disease on human skeletons provide archaeologists with valuable insight into our ancestors’ health and lifestyles and can provide a lot of information about the health of a person or a population,” said Plomp in the report. She has been working with professor Mark Collard in the Human Evolutionary Studies Program, and other researchers from the University of B.C., University of Iceland and University of Aberdeen.
“For example, in ancient remains we can see evidence of metabolic issues, infectious disease, and trauma related to heavy activities or a rough lifestyle,” Plomp added.
The research has been examining the relationship between vertebral shape, upright locomotion and human spinal health, using two-dimensional shape analyses of chimpanzee, orangutan and archaeological human vertebrae, the SFU news report explained.
Plomp’s team found that some characteristics of the human vertebrae differ in shape between individuals who have Schmorl’s node – a small hernia that can occur in the cartilaginous disc between the vertebrae.
She explained: “The humans that have Schmorl’s nodes tend to have vertebral elements with a shape that is statistically indistinguishable from chimpanzee vertebrae.”
“Humans and chimpanzees split from a common ancestor about eight to nine million years ago, and at some point after that split it is thought the human lineage evolved to be bipedal, moving on two rear legs, while the chimpanzees evolved to be knuckle-walkers.”
According to Plomp’s findings, the vertebrae of people with disc disorders more closely resemble those of the chimpanzees’ – human’s closest ape relatives – than the vertebrae of humans without disc problems.
“As evolution occurred, our vertebrae would have changed as we evolved from using some form of quadrupedal locomotion, using four legs, to bipedalism, using two legs,” Plomp said in the SFU news report. “However evolution is not perfect and some vertebral characteristics, such as the ones we identified as being similar to chimpanzees, may have remained within the human ‘blueprint’ and result in some people having vertebrae that are less able to withstand the pressures of bipedal walking.”
The study, in a nutshell, suggests that the pathological vertebrae of some people may be less well adapted for walking upright, said Plomp, calling this the “ancestral shape hypothesis.”
Plomp and Collard are planning to investigate further using 3D shape studies of ancient and modern human and primate spine, and explore other spinal diseases such as osteoarthritis.
Plomp’s findings were recently published in the journal, BMC Evolutionary Biology.
Read more about this study in the SFU news report.
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