The Short Version
Pre-agricultural humans were indeed taller than early farmers, but the claim overstates both the magnitude and the cause. The best transition-era skeletal and genetic studies find a height reduction of roughly 1.5 inches at the Neolithic transition — not 3 to 4 inches. The larger figures require comparing populations separated by tens of thousands of years, conflating multiple evolutionary and demographic changes. Additionally, the dietary attribution is oversimplified: genetics, disease burden, and population density were co-equal drivers alongside nutritional changes.