People generally spend a smaller share of their budget on food as their income rises. Ernst Engel, a Russian statistician, first made this observation in 1857. The reason is that food is a necessity, which poor people have to buy. As people get richer they can afford better-quality food, so their food spending may increase, but they can also afford luxuries beyond the budgets of poor people. Hence the share of food in total spending falls as incomes grow.