In this talk, I will discuss how the application of paradigms from critical phenomena of physical systems at phase transitions can help to explain different sets of natural phenomena out of equilibrium. I will review work ranging from uncovering the geographical patterns in the morphologies of cities and towns, to the scaling laws of economic activity, and finally ending on recent work on the obesity epidemic and the structure of the human brain.

These disparate sets of natural phenomena can be threaded through common patterns of correlations and collective human behavior leading to universality. In particular, we will see how the obesity and diabetes epidemic in the USA can be seen as a manifestation of a critical phenomenon of percolation of human behaviour. We find an interesting regularity in the spatial fluctuations of obesity and diabetes rates per county in USA, revealed by a pattern of scale-free long-range correlations. The analysis categorizes human activity in different universality classes, allowing for the identification of possible drivers behind the obesity epidemic. It suggests that global economic factors, such as the food marketing forces, are driving the rapid rise of obesity above and beyond individual habits. Our classification of health related trends and associated economic factors may be informative for the conception of health policies.