deletions | additions       diff --git a/fc.tex b/fc.tex  index 5770ef1..2e949b9 100644  --- a/fc.tex  +++ b/fc.tex 
...
Once life emerges on a planet, what's the \textbf{probability that will evolve into intelligent life?}. life?}  Depending on the exact definition of intelligence, on Earth it has appeared probably at least a couple of times (\href{http://en.wikipedia.org/wiki/Cetacean_intelligence}{cetacean intelligence}). Intelligence also gives a clear evolutionary advantage and it might represents a common pathway of life. On the other hand, following the same reasoning used for $f_l$, the fact that it took more than 3 billion years for life to evolve from single-celled bacteria to Homo sapiens might argue for a small value of $f_i$. Overall this term is very uncertain; using Frank Drake optimistic guess one has $f_i = 1$. 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. $f_c = 1$