The broader West-Eurasian neotenic gradient, which runs roughly: South Indian →

The broader West-Eurasian neotenic gradient, which runs roughly:

South Indian → Indus Valley → Iranian Plateau → Caucasus → Southeastern European → Western/Northern European

Each step east-to-west represents incremental increases in neotenic selection, average g, and impulse inhibition, largely tracking latitude (pathogen load, winter survival pressure), stability of agricultural surplus, and long-term selection for deferred gratification.