New Evolutionary Theory for the Aetiology of Autism
April 7, 2006 by Kristina Chew, PhD
Filed under Health
Epigenetics News provides a succinct overview of a “mini-review” from the The Journal of Evolutionary Biology that proposes a new evolutionary theory for the aetiology of autism, Imbalanced genomic imprinting in brain development: an evolutionary basis for the aetiology of autism.
Dr. Christopher Badcock and Professor Bernard Crespi propose that autism has been developed through “imbalances in brain development involving enhanced effects of paternally expressed imprinted genes, deficits of effects from maternally expressed genes, or both.”
The authors build on Simon Baron-Cohen’s “extreme male brain theory” of autism and suggest
…a new “extreme imprinted brain theory” that accounts for the sex ratio biases of autism (approximately 4:1 ratio of males to females) and “other observations that are otherwise inexplicable.”
Professors Badcock and Crespi make three predictions from the imprinted brain theory.
First, and most importantly, the primary causes of autism should be alterations in imprinted genes, genes regulated by imprinted genes, and genes associated with the regulation of imprints, via their application and removal (Burt & Trivers, 1998; Wilkins & Haig 2002; Wilkins, 2005). …….
Second, autism may be caused by diverse genetic, epigenetic and environmental factors that cause paternal–maternal brain imbalance (Eigsti & Shapiro, 2003; Lee et al., 2003; Rubenstein & Merzenich, 2003; Cohen et al., 2005; Herbert, 2005).
Third, the behavioural changes involved in autism should reflect extreme manifestations of general, evolved mechanisms for mother–offspring and among-sibling competition over resources. Thus, autism should be thought of as a disorder of kinship interactions, which grade into social reciprocity during childhood via evolved mechanisms for interactions with both kin and nonkin (Alexander, 1990).
I am especially interested in how the researchers’ work incorporates genetics, neuroscience, behavioral observations, and environmental factors–all of which we constantly consider in understanding Charlie and discerning what educational services and other kinds of treatment can most help him.
Another divide and conquer diagnosis which blames the mother and the environment she produces;
“Third, the behavioral changes involved in autism should reflect extreme manifestations of general, evolved mechanisms for mother–offspring and among-sibling competition over resources. Thus, autism should be thought of as a disorder of kinship interactions, which grade into social reciprocity during childhood via evolved mechanisms for interactions with both kin and non kin (Alexander, 1990).”