Some cooking traditions are built on milk, butter and cheese, while others of comparable sophistication use almost none. The pattern follows biology and herding history closely.
Adult digestion of milk is not universal
Nearly all infants produce the enzyme that breaks down milk sugar, and in most mammals production falls away after weaning.
In some human populations that decline did not happen, and adults continued producing the enzyme throughout life.
Those populations cluster geographically rather than scattering at random, and the map of dairy-heavy cuisines overlaps closely with the map of adult enzyme persistence, which is a strong hint that one shaped the other.
Herding came first, tolerance followed
The sequence appears to run from practice to biology. Communities that kept milk-producing animals gained an advantage from being able to use the milk directly.
Where herds were central to survival, dairying became an entire food system rather than an occasional supplement, supporting butter, curds, cheeses, cooking fats and a set of preservation methods built around them.
Where farming favoured rice, fish or pigs, no such pressure existed, and milk stayed marginal or absent from the kitchen even in regions where animals capable of producing it were kept for other purposes.
Fermentation is the workaround
Fermenting milk converts much of its sugar into acids, which is why yoghurt and aged cheeses are tolerated by many people who cannot drink fresh milk.
Several traditions therefore consume dairy almost exclusively in fermented form, and treat fresh milk as a raw material rather than a drink.
That distinction is easy to miss from outside, since a cuisine can look dairy-free while relying heavily on soured products.
Dairy-free cuisines built other fat systems
Where butter was unavailable, the same functional roles were filled by rendered animal fat, pressed seed oils, coconut or nut pastes.
Richness and creaminess were achieved through ground nuts, emulsified stocks or starchy purées rather than through cream.
Which is why substituting dairy into such dishes usually makes them taste unbalanced rather than richer, since the structure already contained its intended fat.
The pattern is shifting, unevenly
Trade and refrigeration have put dairy on shelves in places where it had no culinary history, and it appears mainly in adopted or restaurant food.
Traditional home cooking in those regions has generally absorbed less of it, since the existing dishes were not built around a gap that dairy fills.
Meanwhile plant-based substitutes have spread fastest in dairy-heavy cuisines, where there is a specific function to replace.