The environmental impact of a tossed cigarette butt.
Sierra sat down with Jules Howard, author of new book Sex on Earth, for a totally serious conversation about animal sex.
Three food experts create a holiday feast that will appeal to all eaters.
Reef-building corals have found new refuge in Hurricane Hole.
Just say no to receipts in fast food restaurants--especially if you've used a hand sanitizer--to avoid absorbing or ingesting high amounts of the endocrine-system-disrupting chemical BPA.