Can grandmothers pass immunity to their grandchildren? Does betting on science reveal which studies are worth their salt? And what are the 3000-odd genes you just can’t do without? 24小时娱乐在线's Online 24小时娱乐在线 Editor David Grimm chats about these stories and more with 24小时娱乐在线's Sarah Crespi. Plus, Lauren Sallan discusses the consequences of a mass extinction event 359 million years ago on vertebrate body size.