Olduvai domains: humanity's lucky brake.

Neoteny-a developmental slowdown that results in the retention of juvenile traits into adulthood-has long been viewed as central to human brain expansion. Olduvai domains are proposed here to function as a dosage-dependent metabolic 'brake' that slows development via mitochondrial downregulation. Their human-specific hyperamplification, paired with NOTCH2NL accelerators and new metabolic insights, may solve a century-old evolutionary puzzle.