Why is life complex and — most importantly — what is the origin of the over abundance of complexity in nature? This is a fundamental scientific question which, paraphrasing the late Per Bak, “is screaming to be answered but seldom is even being asked”. In this lecture, we will discuss recent attempts across several scales to understand the origins of complex biological problems from the perspective of critical phenomena. To illustrate the approach, four cases are discussed, namely the large-scale brain dynamics, the characterization of spontaneous fluctuations of proteins, the microbial collective dynamics and the physiological complexity of the cell mitochondria network.