What makes human cognition so much different from that of other animals? The short answer has to do with a single brain network: the default mode network (DMN). Humans are deliberative, able to flexibly combine the current moment with the past so that we can simulate and predict the future. We can remember things that occurred years and even decades ago and we can plan for life events that won't happen until well into our future. This allows us to build meaning and to develop identity and a sense of self. It allows us to build and navigate complex social environments and to maintain complicated long-term relationships. Modern neuroscience is showing that all of these incredible abilities are due to the expansion of a particular group of brain regions in humans that together make up what's collectively called the default mode network.