| War of the genetic roses |
[Sep. 4th, 2008|12:36 pm] |
A tug of war between maternal and paternal genes (which has already shown to affect body weight) may also affect mental development:
In summary, we propose that autistic spectrum conditions are characterized by deficits in theory-of-mind skills, or 'hypo-mentalism', whereas psychotic spectrum conditions involve the exact opposite: 'hyper-mentalism'.
According to this theory, small deviations in imprinted-gene expression towards a maternal bias should result in smaller babies that are energetically 'cheaper' to mothers, and who are easier behaviourally — more placid, less demanding and more mentalistically attuned to interpreting and understanding the mental states of others. Large maternally biased deviations should lead to psychosis. Conversely, small alterations towards paternal bias should lead to relatively demanding children who are more focused on 'things'; larger paternal biases should cause the severe hypo-mentalistic deficits of autism. Between these extremes would sit normal cognition. Highly speculative, but quite curious. |
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Yeah, Crespi's been beating this drum for a few years if memory serves. It's retarded, of course -- schizophrenia doesn't typically set in until well past the age when maternal resources are crucial, and there's really no reason to believe schizophrenics have some kind of adaptive overshoot for their "theory of mind". You'd expect them to be extremely empathetic, but they're the opposite if anything. And if genetic conflict is the story you'd actually expect male genes to promote greater ability to manipulate the mother. Not to mention the fact that it still doesn't explain how an allele that causes this kind of overshoot sometimes manages to compensate for the loss of spending a portion of its time in a body with strongly reduced fitness. I could go on.
![[User Picture]](http://l-userpic.livejournal.com/19075811/333372) | From: ![[info]](http://l-stat.livejournal.com/img/userinfo.gif) tdj
2008-09-04 11:52 pm (UTC)
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I honestly don't know enough about schizophrenia to comment. As far as manipulation goes, I'm not sure I know what techniques are most useful for an infant when it comes to snagging attention and resources. In the womb, that's been well documented. Outside of it, I haven't the foggiest.
In flies the hormonal gender battle is brutal. I can imagine these sorts of tradeoffs on the gene level - if the gene only dramatically reduces fitness in a relatively small number of carriers, assuming that in all but a small number of genetic combinations, the extremes will be confounded by the presence of other genes (or other versions of the same gene).
I'll credit them for starting from an idea that isn't ludicrous on its face -- intragenomic conflict can cause bad stuff to persist at high frequencies in principle. Certainly I've certainly heard worse theories. But in this case it's a stretch for a whole bunch of boring reasons, and I'm suspicious of anything that wraps up two complicated disorders in one neat little package.
Infection, to name one thing, would be where I'd look first in schizophrenia -- there's been statistical evidence suggesting a link between it and toxoplasma gondii, borna virus, and maternal influenza, but I haven't looked too closely at it. I do know that the incidence of it clusters more in cities than rural areas, and even in neighborhoods apparently. Makes more straightforward evolutionary sense, too. Autism I'm not really sure about.
irony/
I don't know why anyone would be surprised that research would show that it's always the mother's fault.
/irony | |
