Building on Andler’s (2017) idea of situation intelligence (SI) encompassing standard measures in terms of multiple abilities (e.g., problem solving, learning and reasoning, memory, language, and complex tool), we observe that the capacity for intelligence relates to the organism’s information capacity derived from its brain (synaptic) plasticity. We offer an extension of SI for individual organisms to collective intelligence (CI) for groups, from family and organization to society and state and even to our species. This enables us to explore the intriguing idea of Intelligence Darwinism and demonstrate how information and intelligence capacities working in tandem shapes natural selection through inter- and intra-species competition thereby delivering biodiversity. With engaging examples and simple explanations, we seek to unravel the ways in which intelligent decision making delivers survival of the smartest from the lowly worm, C. Elegans, whose brain has 302 neurons and about 7000 synapses to homo sapiens being endowed with 86 billion neurons and more than 100 trillion synapses. It has not escaped our attention that this research has natural implications for what AI may portend for the future of our species.