How long would it take you to fall through Earth? Do some human guts harbor ancient bacteria? And are we carrying a lot of genes that we don’t need? Science’s Online News Editor David Grimm chats about these stories and more with Science’s Susanne Bard. Also, Cathy Spatz Widom discusses whether child abuse is transmitted across generations. Angela Colmone has a roundup of advances in immunotherapy from Science Translational Medicine.