In this morning's journal club we discussed Fowler and Christakis's "Dynamic spread of happiness in a large social network: A longtiudinal analysis over 20 years in the Framingham Heart Study". The authors are American doctors working in the field of medicine, public health and political science. Their work makes use of the Framingham Heart Study to analyse family and friendship ties, diet, lifestyle and a sense of well-being and have demonstrated that these behaviours and moods can spread through social networks similar to viruses. Obesity tends to spread through same-sex friendships. Starting and stopping smoking is more contagious than obesity and spreads across both sexes while the transmission of happiness tends to involve face-to-face happiness. Their new book is called Connected.