According to an article on space.com, mathematics may not be the best answer if and when we communicate with ET. Recently, the SETI Institute brought together several anthropologistand professionals from other academic disciplines in an attempt to further understand a potential human and ET communications.
A quote from the article:
[Several participants of the San Jose meeting advised care in assuming that human ways of understanding the universe will necessarily be mirrored on other planets. "Reliance on mathematics as a major means of communication with extraterrestrial intelligence may be misplaced," cautioned historian Shirley Woolf. In contrast to the view that mathematics is a direct reflection of the structure of the universe, which would necessarily be known by scientists on other worlds, Woolf emphasized a view espoused by some prominent cognitive scientists, that "mathematics is an artifact derived from the specific structure of human embodiment."]
I think this is a very open-minded way to think about such topics. We like to say that we "discovered" mathematics. However, what if it goes deeper than that, and our mathematics is just one of endless ways of expressing such things. It's a large Universe out there, we need not be so "biocentric" to believe that life must have arisen nearly identically to the way it has on Earth, and that civilizations must be cultured by mathematics. Sure, it's a place to start, but let's not forget about the under-dogs.