The secret to living longer may be your social life

David Snowdon tracked almost 700 Wisconsin nuns from the order of The School Sisters of Notre Dame since the mid 1980s. Armed with information about their family backgrounds, education, relationships, writing skills, and ultimately, their autopsied brains, Snowdon tells an unforgettable story—filled with epiphanies—about how to live a meaningful and connected life.

Social neuroscientist John Cacioppo, along with writer William Patrick, do a masterful job in, in illustrating how loneliness impairs our ability to learn and make decisions, and how social isolation leaves a damaging biological footprint on every cell of our bodies.

This book tells a compelling story about the lifelong friendships of 11 women, who sustain their bonds across the distances that divide them, divorce, illness, and all the inconceivable obstacles life throws their way. In an era when people conflate time with friends with hours spent on Facebook with "friends," we get accounts of how women can use social media to enhance their relationships, not replace them.

One hot August day just weeks before my book was published, Marc and I were in steamy Washington DC for a live NPR interview, which is where we learned that our books had a common theme: how weak social bonds are as critical as our tight relationships in preserving healthy individuals and a healthy society. Marc's book makes a powerful case that without conversations and relationships with people from different backgrounds and political leanings, we can't function as a civil society.

I could not have made the case for the transformative effect of face-to-face interaction without the empirical work of these two research powerhouses. Any one serious about learning the mechanisms behind social contagion should read this book.