Dog
Dogs structure human existence to a degree that approaches the infrastructural. An estimated 65 million American households contain at least one dog, with owners reporting average daily interaction times exceeding four hours. The morning walk is non-negotiable. The feeding schedule brooks no delay. The need for attention does not acknowledge professional deadlines.
Research from Uppsala University indicates that dog owners demonstrate lower cardiovascular mortality, reduced rates of depression, and increased social connectivity compared to non-owners. The dog has insinuated itself into the fundamental rhythms of human health and happiness.
Shark
The shark's daily impact upon human behaviour, whilst psychologically significant, remains geographically constrained. Approximately 100 million humans enter ocean waters daily; of these, perhaps several hundred thousand modify their behaviour due to shark concerns. Coastal communities adjust swimming patterns, fishing industries account for shark predation, and tourism operators structure shark encounters as premium experiences.
Yet for the vast majority of humanity, sharks exist primarily as documentary content and distant anxiety. They do not structure morning routines or demand evening walks. Their influence, however terrifying, operates at a remove.
VERDICT
The dog demands daily attention from hundreds of millions of humans. The shark influences perhaps hundreds of thousands. Scale determines the victor.