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Thread: Scoliosis in the context of human evolution

  1. #1
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    Scoliosis in the context of human evolution

    Interesting paper discussing scoliosis in the context of human evolution... (emphasis added)

    A Homo erectus skeleton was found to have substantial scoliosis. "KNM-WT15000 H. erectus" is Turkana Boy which is 1.6 million years old.

    http://www.talkorigins.org/faqs/homs/15000.html

    http://www.algoless.com/pdf/human_gait.pdf

    4.4. Clinical implications afforded by the fossil record of
    our spine: scoliosis


    The above conclusion is of interest with respect to the
    incidence of a modern human malady, idiopathic scoliosis.
    In a recent survey of a large sample of great ape skeletons
    by B.M. Latimer of the Cleveland Museum of Natural History,
    no cases of scoliosis were observed in several hundred
    chimpanzee and gorilla spines.

    Such a finding is in accord with the observations of Lowe
    and colleagues [46]. “Naturally occurring scoliosis in vertebrates
    is seen almost exclusively in humans. . . .[I]t has been
    difficult to distinguish causative factors from those that may
    result from the condition. . . . The current thinking is that
    there is a defect of central control or processing by the central
    nervous system that affects a growing spine. . . and that
    the spine’s susceptibility to deformation varies from one individual
    to another” ([46], p. 1165). However, “[a]ny hypothesis
    that proposes a neurological defect must account
    for the impression that many patients with idiopathic scoliosis
    have above-average ability in sports.
    These observations
    have been largely anecdotal, but a study of girls attending
    ballet school showed that the prevalence of scoliosis may be
    as high as 20 percent” ([46], p. 1162).

    These conclusions are fully concordant with the highly
    unusual “situation” that characterizes modern humans, viz.,
    a re-elongated lower spine with what can only be described,
    compared to other primates with long lower spines, as a
    “semi-competent” erector spinae.
    Significant lumbar deviation
    is prevented in apes by their precipitous lumbar reduction,
    lumbar vertebra “capture” by their ilia, and in Old
    World monkeys by their massive erector spinae (Fig. 7).
    While this may not account for idiopathic thoracic manifestations
    of the disorder in humans, subtle imbalances in
    the elongated human lumbar spine might possibly play an
    initiating role even though they would remain subclinical
    until downstream and more cranial effects became more
    prominent.

    At a minimum lumbar scoliosis is seriously debilitating
    and should have long been a target of strong selection. Why
    is it still prevalent in humans? The logical response is that
    selection for effective bipedality must have been so vigorous
    in the ancestors of A. afarensis that functional lordosis was
    facilitated despite the increased risk of scoliotic deviations
    and flexion-induced injury permitted by a semi-competent
    erector spinae.
    The functionally elongated lumbar column
    of Australopithecus and its descendants must have predisposed
    them to even greater rates of spinal pathology than
    occur in modern humans. It is important in this regard that
    the spine of KNM-WT15000 H. erectus skeleton displays
    substantial evidence of scoliosis, including both thoracic
    asymmetry and vertebral fracture (J.C. Ohman, B.M. Latimer,
    personal communication; observations by the author).
    Risk of scoliosis may have served as the most prominent selection
    factor favoring reduction in the length of the human
    lumbar column over the course of the Plio-Pleistocene.
    Sharon, mother of identical twin girls with scoliosis

    No island of sanity.

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    Worth checking out

    Whenever I see a topic about Scoliosis and natural selection I figure it's worth checking out.

    This sentence stood out for me.

    At a minimum lumbar scoliosis is seriously debilitating and should have long been a target of strong selection. Why is it still prevalent in humans?
    That's a good question with a fairly obvious answer. Scoliosis exists for the same reason that other common diseases exist.

    Exhibit
    A) Schizophrenia (Flu During Pregnancy May Increase Risk Of Schizophrenia In Certain Offspring)
    B) Crohn's Disease (Bacteria Identified That May Lead to Inflammatory Bowel Disease in Certain Individuals)
    C) Multiple Sclerosis (Further Evidence Links Epstein-Barr Virus and Risk of Multiple Sclerosis)

    Scoliosis is triggered by environmental damage of unknown origin. It's possible that genes play a role in susceptability. That's the direction science is headed.

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    natural selection

    One more thing stood out

    Risk of scoliosis may have served as the most prominent selection factor favoring reduction in the length of the human lumbar column over the course of the Plio-Pleistocene.
    If the length of the spine was the primary predisposing factor for Scoliosis what about the Giraffe or a hundred other species that support long spines or necks? To the best of my knowledge idiopathic Scoliosis is a human problem.

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    Idiopathic scoliosis of a genetic origin has been shown in guppy. So only human and guppy so far.

    But mainly I am relieved that anyone on here will publicly accept or not question:

    1. natural selection
    2. a 1.6 million year age for Turkana Boy
    3. human evolution FULL STOP

    Only 25% only 45% of the US populace in on board with reality in this regard depending on how the polls are worded.

    Reality... more than just a good idea...
    Sharon, mother of identical twin girls with scoliosis

    No island of sanity.

    Question: What do you call alternative medicine that works?
    Answer: Medicine


    "We are all African."

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    i was wondering whether any animals...besides humans...have curved spines, and if so, whether or not it is called scoliosis...but feared it was too silly to ask...
    am glad someone did ask the question...

    and i'm grateful my puppy has a straight spine!

    jess

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    Apparently, scoliosis can be induced in other animals by various methods.

    But only humans and guppy (and maybe one other fish species IIRC) have a genetically-driven scoliosis.

    I think there will be more discoveries of genetically-driven scoliosis in other animals the more they look.
    Sharon, mother of identical twin girls with scoliosis

    No island of sanity.

    Question: What do you call alternative medicine that works?
    Answer: Medicine


    "We are all African."

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    Jess on a differnt website it show a pic of a cat that has scoliosis
    Kara
    25
    Brace 4-15-05-5-25-06
    Posterior Spinal Fusion 3-10-10
    T4-L2
    Before 50T
    After 20T

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    Giraffe

    Sharon, mother of identical twin girls with scoliosis

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    "We are all African."

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    That is very weird seeing pics of a giraffe with a crooked neck like that. Giraffes have always fascinated me.

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    Genetic driven Scoliosis

    But only humans and guppy (and maybe one other fish species IIRC) have a genetically-driven scoliosis.
    I gotta add that human Scoliosis is idiopathic. Scientists don't know if the cause is genetic, environment or some combination of the two.

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    Gemina (giraffe)

    Gemina the Giraffe

    Gemina (July 16, 1986 – January 9, 2008) (pronounced Jeh-MEE-nah) was a 12-foot-tall Baringo giraffe who lived in the Santa Barbara Zoo in Santa Barbara, California. She became notable for the peculiar deformity in her neck, which was bent by almost ninety degrees between her C3 and C4 vertebrae. The deformity was not present when she was born, in the San Diego Wild Animal Park, but first became noticeable when she was three years old.
    The last time that this type of a deformity had been documented in a giraffe was 1902.

  12. #12
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    Quote Originally Posted by Dingo View Post
    I gotta add that human Scoliosis is idiopathic. Scientists don't know if the cause is genetic, environment or some combination of the two.
    Researchers in the field accept that idiopathic scoliosis has a genetic component. That genetics is involved is a given at this point. I haven't come across an instance of a scoliosis researcher who says there is some chance genetics is not involved. Have you?

    Here is a typical treatment of the acceptance as fact of genetics as a factor in idiopathic scoliosis that can be found in the literature... (emphasis added)

    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2674301/

    Understanding Genetic Factors in Idiopathic Scoliosis, a Complex Disease of Childhood
    Carol A Wise,1,2,3* Xiaochong Gao,1 Scott Shoemaker,4 Derek Gordon,5 and John A Herring2,6
    1Seay Center for Musculoskeletal Research, Texas Scottish Rite Hospital for Children, Dallas, TX
    2Department of Orthopaedic Surgery, University of Texas Southwestern Medical Center, Dallas, TX
    3McDermott Center, University of Texas Southwestern Medical Center, Dallas, TX
    4Department of Orthopedics, Kaiser Permanente, San Diego, CA
    5Department of Genetics, Rutgers University, Piscataway, NJ
    6Dept. of Orthopaedic Surgery, Texas Scottish Rite Hospital for Children, Dallas, TX, USA
    *Address correspondence to this author at the Seay Center for Musculoskeletal Research, Texas Scottish Rite Hospital for Children, 2222 Welborn St, Dallas, TX 75219, USA; Tel: 214-559-7861; Fax: 214-559-7872; E-mail: carol.wise@tsrh.org

    Abstract
    Idiopathic scoliosis (AIS) is the most common pediatric spinal deformity, affecting ~3% of children worldwide. AIS significantly impacts national health in the U. S. alone, creating disfigurement and disability for over 10% of patients and costing billions of dollars annually for treatment. Despite many investigations, the underlying etiology of IS is poorly understood. Twin studies and observations of familial aggregation reveal significant genetic contributions to IS. Several features of the disease including potentially strong genetic effects, the early onset of disease, and standardized diagnostic criteria make IS ideal for genomic approaches to finding risk factors. Here we comprehensively review the genetic contributions to IS and compare those findings to other well-described complex diseases such as Crohn’s disease, type 1 diabetes, psoriasis, and rheumatoid arthritis. We also summarize candidate gene studies and evaluate them in the context of possible disease aetiology. Finally, we provide study designs that apply emerging genomic technologies to this disease. Existing genetic data provide testable hypotheses regarding IS etiology, and also provide proof of principle for applying high-density genome-wide methods to finding susceptibility genes and disease modifiers.

    Is IS genetic?

    The recognition of genetic influences in IS is well-documented [19-25]. Familial forms of IS were described as early as 1922 [26]. Since then, reports of multiple twin sets and twin series have consistently shown higher concordance in monozygotic (MZ) compared to dizygotic (DZ) twins (reviewed in [27]). A meta-analysis of these clinical twin studies revealed 73% MZ compared to 36% DZ concordances [28]. Interestingly, in this series there was a significant correlation with curve severity in monozygous twins (P<.0002), but not dizygous twins. No correlation with curve pattern was found, suggesting the importance of genetic factors in controlling susceptibility and disease course, but not necessarily disease pattern. More recently, Andersen et al. [29] reported their findings using the Danish Twin Registry. They found 25% proband-wise concordance in monozygotic twins (6 of 44 concordant) compared to 0% concordance (0 of 91) in dizygotic twins, with an overall prevalence of approximately 1%. The lower concordances in both groups as compared with prior results may be explained by differences in study design, specifically, ascertainment in clinics versus by registry, and screening by examination versus questionnaire. Nevertheless the overall trend obtained for all studies suggests strong genetic effects in IS. Interestingly, measured concordances in monozygotic twins were below 100%, reflecting the complexity of disease and suggesting the involvement of as yet unknown environmental or stochastic factors in disease susceptibility.

    How is IS Susceptibility Inherited?
    Given that genes contribute to IS, how is disease susceptibility inherited? Autosomal dominant inheritance has been suggested [19-26] from evaluation of single families or small family collections (Fig. (​22)). X-linked dominant inheritance has been a prevailing theory to explain apparent lack of male-male transmission [22]. However this was disputed after re-evaluation of X ray data from original study subjects [23, 27]). Various studies have found that IS disease risk falls off quickly comparing first-degree relatives of a proband to subsequent generations. Other studies found similar trends [23-25]. Specifically, in their comprehensive population study Riseborough et al. reported overall risk to first-degree relatives of 11% compared to 2.4% and 1.4% in second- and third-degree relatives [23]. Interestingly, some but not all studies have found advanced maternal age for mothers of probands with IS [23-25, 30]. These observations may be most consistent with a multifactorial inheritance model involving several to many genes, interplaying with unknown environmental factors. The general consensus gathered from all of this is that, while families with dominant inheritance may exist, IS is generally a “complex” genetic disease that is not easily explained by existing inheritance models.
    Last edited by Pooka1; 11-26-2010 at 07:57 PM. Reason: add link
    Sharon, mother of identical twin girls with scoliosis

    No island of sanity.

    Question: What do you call alternative medicine that works?
    Answer: Medicine


    "We are all African."

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    Mostly when people say something is genetic, they mean that the etiology is known and it's genetic. I know that's not the formal definition of a genetic cause, but that is how it's commonly used and understood.

    So, Down's syndrome is a genetic disease - genetics are sufficient to describe the disorder.

    With scoliosis, the cause is unknown (as both articles state). That genetics play a role doesn't really distinguish it from any other disorder, most of which have at least some genetic predispositions. I mean, they talk about alcoholism having a genetic basis, but we don't really think of it as a genetic disease, and I suspect a good part of the etiology of alcoholism is not genetic. I think the same things at play with scoliosis. There are probably some forms that are strongly genetic, but in most cases genes are just a predisposing factor.

    I'd call AIS, like most other disorders, non-genetic, except in those few cases where it can be traced specifically to genes. Otherwise, like every other disorder, it's a genetic predisposition coupled with environmental factors. In usual parlance, that's not called a genetic disorder.

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    There is a claim on this thread that the jury is still out about whether genetics plays a role at all.

    That is false. Genetics is a given in idiopathic scoliosis. A strong given buttressed by a lot of specific evidence per the paper I posted.

    At this point, if an environmental factor is involved, it almost certainly must be ubiquitous or nearly so. If that is right then the genetics alone will appear to determine the incidence. Six on one hand, half a dozen on the other.

    Genetics being involved to a great degree can be elevated to a FACT per how the researchers treat this in print.
    Sharon, mother of identical twin girls with scoliosis

    No island of sanity.

    Question: What do you call alternative medicine that works?
    Answer: Medicine


    "We are all African."

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    There doesn't appear to be any room for doubting a strong genetic component to idiopathic scoliosis per these quotes. If you find some researchers who are doubting a strong genetic component in print I'd like to see it.

    Twin studies and observations of familial aggregation reveal significant genetic contributions to IS.
    Several features of the disease including potentially strong genetic effects, the early onset of disease, and standardized diagnostic criteria make IS ideal for genomic approaches to finding risk factors.
    The recognition of genetic influences in IS is well-documented [19-25].
    No correlation with curve pattern was found, suggesting the importance of genetic factors in controlling susceptibility and disease course, but not necessarily disease pattern.
    Given that genes contribute to IS, [...]
    Sharon, mother of identical twin girls with scoliosis

    No island of sanity.

    Question: What do you call alternative medicine that works?
    Answer: Medicine


    "We are all African."

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