Are older people more likely to be politically conservative and why?
As a neuroscientist, I would be highly doubtful of any neuroscientific 'evidence' about this phenomenon (if it exists). In fact, I think there is no reason to look further than the mere exposure effect:


  The mere-exposure effect is a psychological phenomenon by which people tend to develop a preference for things merely because they are familiar with them.


Conservative attitudes are by definition more traditional, i.e. those who have been around for a longer time... just like older people. Older people have, therefore, had more chance to become familiar to conservative attitudes through exposure.