User blog comment:Mckrongs/Monster Hunter 4 for the Nintendo 3DS/@comment-21378804-20131003110715/@comment-4212769-20131003151401

Abstract thinking increases the intelligence. The more you train your brain, the smarter you get. That's a proved fact. That's why they also get smarter for thinking more because they need to compensate their disadvantage of being easier seen. For that they need to get better strategies for hunting and territorial fights. Because they increase as well when you get seen easily in your habitat.

To give you an example:

Someone that wears unusual clothes gets seen easier in a crowd and other people judge them more.

The same principle goes for the Pink and the Azure Raths. While the green Rathian in the Jungle may be not seen by a territorial monster, the Pink is seen pretty well in the green forest. So a rival would judge the Pink Rathian as a threat and sees her as intruder of its territory so it would provoke a fight. And as those fights become more often when you're better seen, you obviously get more battle harden.

Moral of the story: Mental and physical training increases mental and physical capacities.