Before we get into this week's topic, check out Chris and Dave's recent appearance on NHPR's Outside/In. They joined host Sam Evans-Brown for a special edition of "Ask Sam" . There are few sounds in nature that command your attention as effectively as the rattle of a rattlesnake. And though these snakes are not aggressive, that sound does elicit a hard-wired, innate fear response. Roughly translating to “Watch Your Step, Mister!” the rattle is an alarm designed to stop trouble before it starts.