Robert Sapolsky's organizing structure: any single human behavior can be explained simultaneously across radically different time scales, from milliseconds to millennia.

The layers he works through, from immediate to ancient:

• Neurons firing in the second before the behavior
• Hormones acting over the preceding minutes to hours
• Childhood development shaping the brain over years
• Evolutionary pressures shaping the species over millennia

Sapolsky's core argument: none of these levels alone is "the" explanation — a complete account of any behavior requires holding all of them simultaneously, resisting the temptation to pick a single favorite causal layer.