Humans generally have difficulty digesting milk from animals other than cows, goats, and sheep. The milk from these animals contains lactose, a natural sugar, and lactase, the enzyme needed to digest it. However, when it comes to milk from animals like camels, horses, and whales, it is often not well tolerated by many humans due to the differences in lactose content and composition. These types of milk can be challenging for many people to digest, potentially leading to digestive discomfort and symptoms like diarrhea and bloating because of the differences in lactose content and composition.