Relative Likelihood of Success in the Searches for Primitive versus Intelligent Extraterrestrial Life

Abstract

We estimate the relative likelihood of success in the searches for primitive versus intelligent life on other planets. Taking into account the larger search volume for detectable artificial electromagnetic signals, we conclude that both searches should be performed concurrently, albeit with significantly more funding dedicated to primitive life. Based on the current federal funding allocated to the search for biosignatures, our analysis suggests that the search for extraterrestrial intelligence (SETI) may merit a federal funding level of at least $\$10$ million per year, assuming that the average lifetime of technological species exceeds a millennium.