Medicine & Health

Epidemiology: Everything Turns on One Number Crossing One

If each case produces more than one further case, an outbreak grows; below one, it fades. That threshold is simple — and almost everything else about the subject is context-dependent.

Neuroscience: The Brain Rearranges Itself Around What You Do

The computer analogy breaks down at the most important point — the hardware physically changes with use. That single property explains most of what is practically known about learning.

Longevity and Health: The Big Effects Are the Ones Nobody Sells

The interventions with the largest effects have been known for decades and are unglamorous. Attention flows almost inversely to effect size, for a simple reason — the big ones cannot be sold.

Hormesis: The Dose Decides Whether It Helps

Lifting weights tears muscle, and the tearing is the point. A small dose of something harmful can trigger a repair response that leaves you stronger — but only under two specific conditions.