Common back problems may be caused by evolution of human locomotion

April 27, 2015 by Joel Winston, BioMed Central
Credit: public domain

A common spinal disease could be the result of some people's vertebrae, the bones that make up the spine, sharing similarities in shape to a non-human primate. The research, published in the open access journal BMC Evolutionary Biology, suggests that the relatively quick evolution of the ability to walk on two legs may have had a substantial impact on modern human health.

Humans are more commonly afflicted with spinal disease than non-human primates, and one widely discussed explanation for this is the stress placed on the by bipedal locomotion. This research backs up this theory.

A widespread cause of back pain, 'intervertebral ', has prevalence rates ranging from 20% to 78%, depending on the population. It is caused by the prolapse of a gelatinous substance inside the disc, and when the herniation is vertically directed it is often characterised by protrusions of cartilage called 'Schmorl's nodes'.

Researchers studied the vertebrae of humans, chimpanzees and orangutans to examine links between vertebral shape, locomotion, and the appearance of vertical disc herniation in humans.

Postdoctoral researcher Kimberly Plomp from Simon Fraser University, Canada, said: "Our study is the first to use quantitative methods to uncover why humans are so commonly afflicted with back problems compared to non-human primates. The findings have potential implications for clinical research, as they indicate why some individuals are more prone to back problems. This may help in preventative care by identifying individuals, such as athletes, who may be at risk of developing the condition."

The researchers compared 141 human vertebrae, 56 chimpanzee vertebrae (a knuckle-walking primate), and 27 orangutan vertebrae (a climbing primate that uses all four feet which are modified as hands) and found significant differences in their shape. They say this could be explained by the different modes of locomotion and contributes to the understanding of the human evolution of bipedalism.

Of the human vertebrae they studied, 54 had 'Schmorl's nodes', the skeletal indicators of vertical disc herniation. The researchers found that human vertebrae with Schmorl's nodes shared more similarities in shape with chimpanzee vertebrae than the healthy human vertebrae shared with those .

This suggests that vertical disc herniation preferentially affects human individuals with vertebrae that are towards the ancestral end of the range of human shape variation. These individuals may therefore be less well-adapted for bipedalism and suffer more from load-related spinal disease.

The authors say their findings could be used for interpreting medical scans of spinal disease. This could help clinicians investigate an individual's vertebral shape and predict their susceptibility to intervertebral disc herniation.

The identification of an ancestral vertebral shape that influences the occurrence of a common spinal disease in humans also supports the idea that the relatively quick evolution of bipedalism may have had a substantial impact on modern human health.

The authors note several study limitations such as small sample sizes, and including humans that are derived from Medieval and Post-Medieval English populations. Future research will include larger sample sizes and multiple human populations from different ancestral backgrounds. It will also include the analysis of CT scans of living individuals in order to study horizontal herniations that do not leave evidence on the , and focus on capturing the 3D shape of human and non- primate data to capture vertebral elements that have been missed in the present study.

The research team included Mark Collard from Simon Fraser University, Darlene Weston from the University of British Columbia, Una Strand Viðarsd?ttir from the University of Iceland, and Keith Dobney from the University of Aberdeen.

Explore further: Minimally invasive spinal fusion: Less pain, faster recovery, smaller scar

More information: Kimberly A Plomp, Una Strand Vidarsdottir, Darlene A Weston, Keith Dobney and Mark Collard, The ancestral shape hypothesis: an evolutionary explanation for the occurrence of intervertebral disc herniation in humans, BMC Evolutionary Biology 2015. DOI: 10.1186/s12862-015-0336-y

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JVK
1 / 5 (3) Apr 27, 2015
Let's compare evolutionary explanations.

The bacterial flagellum that enables locomotion re-evolved "over-the-weekend" in this study.
Evolutionary resurrection of flagellar motility via rewiring of the nitrogen regulation system
http://www.scienc...abstract

These researchers "...compared 141 human vertebrae, 56 chimpanzee vertebrae (a knuckle-walking primate), and 27 orangutan vertebrae..."

Dobzhansky (1973) claimed "...the so-called alpha chains of hemoglobin have identical sequences of amino acids in man and the chimpanzee, but they differ in a single amino acid (out of 141) in the gorilla" (p. 127). http://www.jstor..../4444260

No changes evolved during the past 1.8 billion years in this species of bacteria.
Sulfur-cycling fossil bacteria from the 1.8-Ga Duck Creek Formation provide promising evidence of evolution's null hypothesis http://www.pnas.o...abstract
JVK
1 / 5 (2) May 18, 2015
Of course I do. I spoke with Diego, for example, at his SFN poster session in 2012 about the fact that others denied the possibility of the gut-to-brain connection he had made.

http://medicalxpr...ain.html

I was reminded of that fact when I received the notice that he will be speaking in Atlanta on Wednesday.
--
Please join us for an upcoming Neuroscience Institute research seminar this Wednesday, May 20th at 10am in 124 Petit Science Center. Feel free to distribute.

Dr. Diego Bohorquez will be giving a talk entitled "Where the gut meets the brain".

More information on Dr. Bohorquez's research can be found here: Dr. Diego Bohorquez on Google Scholar

Please tell him I said hi, if you attend the presentation. In any case, what makes you think you are qualified to claim that I cannot comprehend what I cite?

Do you think you known something about RNA-mediated cell type differentiation that I have not yet learned?

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