I think an underappreciated factor in the drake equation is whether an intelligent species is able to form and maintain societies. For all our issues as a species, we're surprisingly good at forming everything from tribes to nations...
Humans are interesting because we're one of the few semi-social animals. If you're tribe/village is whipped out, you'll die soon too. But just because your group flourishes doesn't mean your genes will even be passed on (like they would in an ant colony). So we have all these behaviours (like empathy and cooperation) but they're finely balanced and complex (unlike an ant that will die for the colony without hesitation). The lack of top down control and the requirement for cooperation means communication abilities are vital and have to be complex and suddenly you have a brain that needs to simulate other brains (empathy) and consciousness is born.
