Prior to the 1970's, "parenting" was an unfamiliar term. Most moms and dads thought of it as child rearing. And from the earliest days of parenting forward, humans embraced something called alloparenting, essentially getting someone else to take of your kids for you. We talk to the author of a new book all about the history of parental behavior, from the things we accept as good parental behavior and the others we accept as bad for no apparent reasons.