Aesthetic valuation is grounded on brain systems that evolved to assess the hedonic value of sensory stimuli. The fact that other animals show similar preferences for perceptual attributes and comparable sensory valuation systems suggests a common evolutionary history. This chapter provides a selective summary of what is known about the origin and evolution of these sensory valuation systems. We show that these systems originated in the earliest single celled organisms, close to 900 million years ago, and that they have been evolving ever since. We divide this evolution into six major stages and show how the way sensory valuation systems became wired throughout these evolutionary stages explains why we like things and find them beautiful. The attributes of the biological systems underlying aesthetic liking, and of the cultural artefacts humans have invented to stimulate these systems, were shaped by their original function of organizing animal behaviour in adaptive ways.