Thursday, July 28, 2011
Autism and Phenotypic Plasticity
Recent research has underscored the large environmental influences in autism. These studies have reconfirmed that autism is not only driven by genetics but can be strongly associated with particular environmental situations. I have long had a hunch that autism may be linked with specific environmental cues that are predictive of the quality of the social environment that the fetus can expect to be born into. Research in the field of phenotypic plasticity and epigenetics has shown that many organisms, from plants to flies to people demonstrate predictive adaptive responses to particular environmental stressors. Environmental cues encountered early in life are used by the developing organism to fine-tune its body type, above and beyond what its genes have in store for it.
My intuition tells me that many social mammals may be receptive to certain foreboding environmental cues that give them information about the social environment that they can expect after birth. It is already known that rats and humans respond in a similar way to cues about stress. Researchers like Michael Meaney at McGill University have documented that stress responsiveness can be largely programmed in young rats. The frequency of early cues indicative of maternal care (such as the extent of early maternal stress, arched back nursing, licking and grooming) modulate the expression of genes that regulate behavioral and neuroendocrine responses to stressors. In other words, the bodies of young mammals genetically modify themselves to ensure that they are better prepared for a threatening environment.
I imagine that there may be similar cues that hold predictive value about the social environment. These have not been found, but this is probably because they have never been looked for. Or have they? It is known that maternal stress, serotonin levels, multiparity and others are risk factors for autism. Could these factors, or some facet of them, offer information to the fetus about the social environment? Are there other cues that the fetus could intercept and respond to that indicate how valuable social cognition has proven to be to their parents?
Take a look at the section on "autism and epigenetic programming" in my article on autism at: http://www.solitaryforager.com/.