Down Syndrome Riddle

December 17, 2008 | 7 Comments

Category: Neoteny

Early last summer, before the conventions, Sarah Palin caused a stir among the parents of children with Down Syndrome.  My Leftist buddy Martin has a kid with Downs.  Martin was moved by this Alaskan elected official’s seeking attention for the disability that his life revolved around.  Martin seriously considered voting for McCain/Palin when Palin was picked as VP.  Until he heard her speak.

I’ve not studied Down Syndrome.  Still, in my explorations of autism, Down Syndrome kept emerging, but I did not swerve to explore its possible connection to the theory I was detailing.  Several things do jump out.  Those details suggest an evolutionary etiology for Down Syndrome.  If supported, advocates like Sarah Palin that lambast evolutionary theory would be left advocating for advances within a discipline that she religiously combats.

Papers heavily support the thesis that Down Syndrome, in males and females, reveals extreme neoteny or maturational delay.  Unlike in autism, where I posit males exhibit maturational delay and females maturational acceleration, all of those with Down Syndrome show extreme neoteny.

“Down syndrome individuals generally have retarded growth and maturational processes with retention of fetal development (“unfinished”) characteristics involving brain, face, and the 5th fingers.  According to Waardenburg (1932) it was Blok in 1922, who first proposed a fetalization theory of Down Syndrome.  From a palaeontological perspective all of these growth disturbances and developmental dysmaturities can be subsumed under the heading of neoteny.  The concept of neoteny was coined by Kollmann in 1885 and refers to the retention of juvenile characters in the adult state, or to extention of fetal characteristics into childhood.” (Opitz, John M. & Gilbert-Barness, Enid F.  (1990) Reflections on the Pathogenesis of Down Syndrome.  American Journal of Medical Genetics 7: p. 44)

Most humans have 46 chromosomes.  Chimpanzees have 48.  A person with Down Syndrome has 47.  The obvious question is whether those with Down Syndrome are transitional and when in our evolutionary past did the transition occur?

There is a higher incidence of autistic and Down Syndrome children being siblings than would be normally estimated.

A far higher number of Down children are left-handed than is the norm.  My evolutionary theory posits we were all random-handed a hundred thousand years ago or so.

Older mothers are more likely to have a Down child.  According to this blog’s thesis, the increased levels of testosterone in an older mother make her more likely to birth a son or daughter from an evolutionary past.

Several studies suggest that Down Syndrome reveals atavisms, or features characteristic of evolutionary progenitors.

Not supporting these ruminations is the fact that those with Down Syndrome are short in stature with unique physiological features.  We have no ancestors of comparable stature or features in our archeological lineage.  The physical handicaps are often profound.  It’s hard to imagine a society of primitives with Down Syndrome characteristics surviving to procreate.

“Thus, with respect to (1) the fixation of a common pattern of major variability easily recognized in every race of humankind, (2) the invariable alteration of numerous morphometric traits and the abolition of family resemblance, (3) change in growth and of maturational characteristics with enhanced neoteny, (4) change in fertility, (5) appearance of a different behavioral phenotype, (6) change in chromosome number, and (7) changes in gene frequency —at least with respect to genes on chromosome 21 (Goodman, 1965; Rundle, 1973; Rundle and Sudell, 1973), we can only conclude that the occurrence of Down syndrome is akin to the process of speciation (albeit a sudden, rather than a gradual speciation).  With respect to the relationship between speciation and chromosome abnormalities it is important to note that the types of chromosome rearrangements ‘that occur as polymorphosisms or as fixed permanent heterozygotes invariably involve meta- or submetacentric chromosomes.  Those that distinguish species and serve to isolate those species involve telocentric or acrocentric chromosomes, which are self sterilizing.’  (John, 1981).”  (Opitz, John M. & Gilbert-Barness, Enid F.  (1990) Reflections on the Pathogenesis of Down Syndrome.  American Journal of Medical Genetics 7: p. 45)

As an extreme example of neoteny, Down individuals are exaggerations of how our evolution might have occurred, without evidence of a dramatically expanded brain.  It seems like Down Syndrome is some sort of alternative reality exhibition of how we could have evolved had our brains not grown at as fast a rate as they eventually achieved.  The clues suggesting that Down Syndrome has an evolutionary etiology are powerful.  Unlike autism, there is not a relatively clear hypothesis or picture of how exactly this occurred.  Still, Sarah Palin, an aggressive, high-testosterone woman who gave birth to her Down child after 40, fits the thesis’s profile of the mother of an autistic child from the past.


Comments

This entry was posted on Wednesday, December 17th, 2008 at 8:13 am and is filed under Neoteny. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
7 Comments so far

  1. Corinne on December 20, 2008 4:10 am

    Does amniotic testing indicate the prescence of Downs Syndrome prior to the 33 week of gestation?
    What other fractors might trigger neoteny ?

  2. Aymee' Sells on March 15, 2009 10:17 pm

    I am a anthropology graduate student working on my thesis regarding Down syndrome. My two year old son has Down syndrome, which has inspired me to get my Ph.D. in genetics, after I complete my Masters in anthropology.

    I need to point out something in regards to your assertions. Not all people with Down syndrome have 47 chromosomes. My son has 46 chromosomes. There are 3 variations of Down syndrome: Trisomy 21, Mosaic, and Translocation. My son does not have the triplication of chromosome 21. Instead, he has extra material located on the long arm of 21.

    Being the anthropologist that I am, evolution cannot work with chromosome duplication. There is not new information within the genes, only duplication of pre-existing information.

    Moreover, there are many children born with Down syndrome to women in their twenties. You do not have to be an “older woman” to have a baby with Down syndrome.

    Furthermore, Stanford University has a huge research team working on finding a treatment for individuals with Down syndrome so that they can lead normal lives. There is a gene called “DYRK1A that over produces protein, which causes learning delays in the hippocampus. There are experiments that have been proven to turn down the protein, or inhibit the protein, so that these individuals can learn just like anyone else.

    I understand that everyone has their own opinion, however, please know all the facts before you form one.

    Best Wishes,

    Aymee’

  3. Justin on May 31, 2010 9:44 am

    Thank you for clearing that up, Aymee. Most people mistakenly take Down Syndrome as proof of evolution. Evolution not only requires *NEW* information to be added, but also that this new information is beneficial.

  4. Lagiusmeatius on July 23, 2011 11:54 pm

    Justin,

    Actually I believe that Down’s Syndrome is one of many instances that demonstrate a proof of evolution. The number of chromosomes present are a factor in evolution as well as the variation in genes. Even if two organisms have the same genes, but they are coded on different chromosomes (a different number for example), this can have profound implications on how certain genes are expressed and of course how they separate and mix with others during reproduction. You have made two incorrect assumptions: that evolution requires “new” information, and that it be beneficial. Actually random changes in DNA (changing the order of a DNA strand can produce a new organism, even if both strands have the same number of every base pair, etc.). Changes need not include “new” information, as rearranging old information also produces a new result. If I copy information, there is no new information, but the redundancy can certainly affect the longevity, fecundity, and fidelity of genes, and thus the organism over time. Changes need not be beneficial. One of the proposed mechanisms for evolution (natural selection) only requires that genes are selected for over time based on environmental pressures. This does not mean that every mutation that occurs over time has to be beneficial, as long as there are SOME changes that are beneficial so as to allow the organism to survive. Why do humans have an appendix? Why can’t Penguins fly? There are many seemingly useless genes that survive simply because there are others that exist that supersede in importance. A tyrannosaurus rex may have little arms, but its large head and sharp teeth afforded it an advantage that compensated for the small seemingly useless arms. Thus, evolution need not involve exclusively beneficial traits, as long as there are SOME traits that allow the organism to fit in to the current (and changing) environment over time. This is why what was once advantageous (being a large dinosaur for example) eventually became a disadvantage compared to mammals that could survive the last major extinction. Both types of species existed, but as soon as the environment changed, mammals started to lead the food chain. So your assumptions on the requirements for evolution are simply not true. Down’s syndrome as well as other genetic “disorders” are evidence of how chromosome numbers or arrangement can change over time, and eventually lead to speciation. Not all changes are seen as benefits in our eyes, but there may be benefits that are unknown (like those with Down’s syndrome may be more capable of unconditional love, a heightened or alternate form of consciousness, or have a chemical resistance that non-Down’s humans lack). Also, any traits that may be seen as disadvantageous in the present environment may become advantageous if the environment changes enough (which is a dynamic process that occurs all the time). One day, humans may see themselves drop down a notch on the food chain, being replaced by a species produced from these genetic variations (i.e. like those with Down’s syndrome, etc.). Down’s syndrome and other chromosomal “abnormalities” may provide a missing link in searching for the multiple mechanisms of evolution (chromosome number changes, like human’s 46 chromosomes forming from other ape’s 48 chromosomes — once there was a fusion of a pair of chromosomes with another). It’s changes like this that illustrate how Down’s syndrome demonstrates one of the mechanisms for genetic evolution over time.

    Peace and Love to you all,
    -Lagius

  5. mk on April 13, 2012 1:16 pm

    “The obvious question is whether those with Down Syndrome are transitional and when in our evolutionary past did the transition occur?”

    It’s a bizarre question. The transition occurred — repeatedly — when the copying error occurred in the parent.

    “Several studies suggest that Down Syndrome reveals atavisms, or features characteristic of evolutionary progenitors.”

    The genome is full of traits, left over from our progenitors, that aren’t normally expressed in humans.

    You really don’t understand evolution very well.

  6. Lage on April 13, 2012 2:32 pm

    “The obvious question is whether those with Down Syndrome are transitional and when in our evolutionary past did the transition occur?”

    I’m wondering if this question is intended to ask how much weight we can put on the genetic code for Down Syndrome with regards to calling a carrier a “transitional” species. When do you say that enough genetic change has occurred to call this new organism a separate species? The strictest definition used in biology tends to define species as being able to reproduce with one another (and in other definitions, not only reproduce but also to fertile offspring which makes more sense when we consider a horse and a donkey bearing an infertile mule). It is an arbitrary line we draw to say what is “transitional” or not, as really every species that isn’t yet another species (depending on how we define the term) is “transitional” as it moves the species one step closer to not being able to reproduce with carriers. Take the case of a sheep and a goat: there was an instance in Europe I believe where a sheep and goat mated and had fertile offspring containing the average number of chromosomes of the two different species parents (a new species or so it seems). Thus one can argue that the definition of species needs to be redefined, since exceptions exist that take meaning away from the current purpose of the word “species”. Obviously what we define as this species or that species is arbitrary to some degree as we can see from a definition that now needs modification. Occurrences like the case involving the sheep and goat make sense because it provides another way to form new species with different numbers of chromosomes (there are many possible ways to accomplish this including genetic mutation, and chromosomal splicing and slicing, and this is just another way for the number of chromosomes to change over time). Those with down syndrome, if able to reproduce (in some instances they can), may be a catalyst for new speciation. What we consider genetic anomalies are all a natural part of genetic evolution, so there you have it.

  7. reviews on October 5, 2014 9:29 pm

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    Down Syndrome Riddle – Neoteny, sexual selection, cause of autism, human evolution, social transformation, left organizing and internet activism – how they all connectat Neoteny, sexual selection, cause of autism, human evolution, social transformation…

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