Alternates have a lower body temperature, answer questions more slowly, do not react to spicy food or strong smells, do not fart, their heads can stretch, and they have an unusual obsession with red milk. They are emotionless and fear strong light, mimicking human actions like doing a split.
The core strategy is a process of elimination. Utilize tools such as a thermal scanner, chili peppers, laptops, canned food, and a flashlight to distinguish Alternates from humans based on their unique characteristics and behaviors.