We Need To Talk About Bird Poop Seabird poop—sometimes called guano—was the “white gold” of fertilizers for humans for millennia. Rich in nitrogen and phosphorus from birds’ fish-based diets, the substance shaped trade routes and powered economies until chemical fertilizers replaced it. But while people may no longer find bird poop profitable, these same poop deposits—often found on islands or coasts where the birds nest and rear their young—may also be nurturing ecosystems that would be left high and dry if the birds were to disappear. As seabird populations quickly decline, that’s becoming an increasing risk. Australian researchers Megan Grant and Jennifer Lavers talk to Ira about the under-appreciated role of bird guano in ecosystems, and why scientists should be looking more closely at the poop patterns of endangered seabirds.     Sweating Is Our Biological Superpower Sweat may feel like a constant summer companion, whether or not you exercise frequently. Being damp can feel uncomfortable, but the smells that follow—thanks to the lives and deaths of sweat-munching bacteria—are often socially stigmatized as well. (Deodorant itself is actually a very recent invention!) But sweat isn’t just a cosmetic embarrassment: It’s crucial to keeping us cool, as the evaporating liquid pulls heat energy from our bodies. If you look at animals that don’t sweat, many have evolved alternate adaptations like peeing or even pooping on body parts to achieve that vital evaporative effect. People who are born unable to sweat run a constant risk of heatstroke. Ira talks to Sarah Everts, author of the new book, The Joy Of Sweat, about what makes sweat useful, the cool chemistry of this bodily fluid, and why it’s our evolutionary superpower.   From Zero To 100 Butts: The Wild World Of Invertebrate Behinds Recently, the staff of Science Friday came across a tweet that caught our attention, sent out by researcher Dr. Maureen Berg. Turns out, it was a call to source comic ideas for Invertebrate Butt Week, a celebration of—you guessed it—the butts of invertebrates. “Invertebrates really get the short end of the stick,” says Rosemary Mosco, the creator of the comic series Bird And Moon and #InverteButtWeek organizer. “People are not as excited about them as, say, a majestic whale or a beautiful bird. And I love my birds, but [invertebrates have] such an incredible diversity. So, butts are sort of a cheeky way to access some of that amazing diversity and celebrate it.” Rosemary and other scientists and illustrators teamed up to create #InverteButtWeek, a celebration of the behinds of the backbone-less. “It’s a chance for some people who do science communication to do the silliest thing that they can possibly think of,” says Dr. Ainsley Seago, curator of invertebrate zoology at the Carnegie Museum of Natural History.   Science Friday’s D Peterschmidt talks to the organizers of #InverteButtWeek about how it came together, their favorite invertebrate butt facts (like how sea cucumbers have anal teeth), and how you can participate in the celebration.   Transcripts are available on sciencefriday.com.       Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.