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The next factor in the Drake equation measures the \textbf{probability of life evolving into "intelligent life".} Intelligence gives a clear evolutionary advantage and therefore it might represents a common pathway of life. Broadly speaking on Earth intelligent life has appeared at least a couple of times (\href{http://en.wikipedia.org/wiki/Cetacean_intelligence}{cetacean intelligence}). However we need to consider that the transition from simple microbial life to complex animals was a very long process. On Earth it took more than 3 billion years for life to evolve from single-celled bacteria to Homo sapiens. Therefore the same reasoning used for estimating $f_l$ might argues for a small value of $f_i$. This value, $f_i<<1$. Note that this  perspective is quite different from the very optimistic view of Frank Drake, who argued that life always evolve into intelligent life, that is $f_i = 1$. To communicate with other intelligent life a civilization has to develope some sort of technology. If again we consider Earth's case, this happened for humans but not, for example, for dolphins. The factor \textbf{$f_c$ measures the fraction of civilizations that develop communicative technology}. As intelligence and curiosity seem to go hand-in-hand, it seems conceivable that all intelligent lifeforms might eventually evolve towards a technological, communicative form. $f_c = 1$