Update (Jan 13): Amygdala stores “Pavlovian fear conditioning” according to the latest PLoS ONE paper on the matter by H.G. Bergstrom and colleagues.
Conservative brains are full of fear
Fans of the classical (but probably incorrect) blank slate hypothesis of the human brain won’t like this: new research (not yet published at a peer review journal, will be in the near future) has found that conservative people have a larger amygdala, a primitive almond-shaped part of the brain responsible for fear and anxiety.
It is unclear if this physical/neurological trait is caused by the ideology, which is clearly based on fear of any change and attachment to some learned values, or if, inversely, it is the biological trait which causes conservative ideology. Different research, earlier this year found that people with more liberal ideology tend to share a variant of the DRD4 gene, which may be a cause of openness to novel ideas (which in turn may increase adaptability, as hyper-specialists invariably go extinct in the long term).
Also, in regard to the role played by the amygdala in fear, you may be interested in this story (another scientific research) about a woman whose amygdalas were destroyed by a disease and who feels no fear whatsoever (what also has its downsides: fear is a natural emotion or instinct that plays a clear role in survival).
Additionally, Razib mentions today that conservatives (in the USA) tend to be fatter than average. Maybe they have to compensate for their quasi-permanent state of panic by giving themselves continuous treats?