Margarine and Trans-Fats were introduced into the population in large volumes just prior to and during WWII. A big advantage of Trans-Fats is its very long shelf life at room temperature. Unlike other fats, they do not spoil and turn rancid. No one asked if humans were designed to eat fat that didn’t rot over time. Is it healthy to eat fat that can survive many years at room temperate? Perhaps it is a vital part of digestion that the fats we eat break down over time so that they do not accumulate in the arteries.