The Science of Why: Answers to Questions About the World Around Us: Summary & Key Insights

Yawning is one of those universal experiences that seem simultaneously ordinary and mysterious. Everyone does it, yet few can explain exactly why. When I first began examining yawning, I expected the answer to be straightforward—some biological mechanism for oxygen intake or fatigue. But what I found was far more intricate, involving a web of neurological and social cues that reveal much about human and animal behavior.

Physiologically, yawning is rooted in the brain’s thermoregulation system. Studies suggest it may help cool the brain, maintaining optimal performance by increasing blood flow and air exchange. This view shifts yawning from a passive sign of tiredness to an active means of keeping your brain alert and balanced. But the mystery deepens when we consider contagious yawning—the fascinating tendency to yawn when someone else does. That contagion appears linked to empathy and mirror neuron activity, the same neural processes that underlie understanding and emotional connection.

When I think about yawning now, I see it as both biological and symbolic—a blend of physical necessity and social resonance. It’s a reminder that even subconscious acts connect us deeply. If we begin to see such simple motions as evidence of an empathy rooted in biology, we can appreciate how every gesture may hold evolutionary echoes of social bonding.

Time is entirely human—but not in the way you might think. We measure it precisely with atomic clocks and mechanical devices, yet our internal experience of time defies linear order. Minutes can stretch when we’re anxious and vanish when we’re absorbed. In this chapter, I explore how our brains construct the illusion of temporal flow.

The psychological sense of time depends on attention and memory. When our brains are busy encoding new information, we perceive time as slower; when our environment is routine, we skip through hours as though they’ve collapsed. Neurologically, time perception involves interactions between the cerebellum, basal ganglia, and prefrontal cortex—all orchestrating the rhythm of lived experience.

Think of childhood summers: the long, lingering days felt spacious because everything was novel. As we age, repetition compresses our sense of duration. Understanding this can change not only how we measure life but how we choose to inhabit it. Our subjective time is malleable, shaped by curiosity and engagement. The more intensely we notice the present, the richer and longer it becomes.