Ernst Mayr and Carl Sagan debate about the probability of intelligent life in the universe

During the Second Iberoamerican Graduate School on Astrobiology interesting debates, between the experts from the biological and physical backgrounds, arose about the probability of the existence of extraterrestrial intelligent beings in the universe. For this reason, it is appropriate to reproduce -for the first time in Spanish- the debate on the subject conducted, in 1995, between Carl Sagan and Ernst Mayr. This debate was organized by Guillermo A. Lemarchand and published in the pages of two consecutive numbers of "Bioastronomy News". Here we reproduce the complete debate, including its original introduction.