Please define the word "rational". Evolved instincts obviously can increase the life expectancy of any organism. That is because the mechanism of evolution is directed by the survival prospects of an oganism (which is quite often correlated with life span). But increased lifespan is not "rationality" is it?
I believe that the concept of "rationality" is made up. Humans invented it to pretend that what they are doing is somehow important in the grand scheme of things. This is is a myth of course. It doesn't mean anything.
Or can you define what "rational" means in a way that doesn't rely on myth (i.e. things that aren't based on provable fact).
The Earth has been around for 5,000,000,000 years. You will be dead in 1 100,000,000th of that no matter how you behave. Keep that in mind when you try to tell me what "rational" means.