There's a dead body behind the science museum. Insects are rapidly consuming the mystery corpse. Maggots pulse and squirm in the eyes and nostrils, beetles gnaw at leathery skin, and flies gorge themselves on putrid flesh. Not so long ago, this mysterious corpse was pink-cheeked, healthy, and … oinking.
Pigs are a lot like people in some ways. With similar organs, muscles and bones, all beneath mostly hairless skin, pigs make reasonable substitutes for human bodies. They have been used as military and medical test subjects for generations, and now they are playing an important part in the scientific study of what happens to us after we die.
Knowing when a pig died, scientists will gather data on the stages of its decay. Criminal investigators can then use this information to reveal a time and place of death when they find a human body in similar condition.
Like a grisly little island, a dead body has a slightly different climate and insect community from the surrounding environment. Flies are the first to arrive at the “island,” laying eggs in body openings, and consuming fluids from the moist tissue. Ants and beetles will then come to prey on the fly eggs and maggots. As the body begins to dry, maggots disappear and other beetle species will move in to chew at the toughening flesh.
The specific combination of insects present can indicate the age of the island—when the body died. Depending on where the body is located, though, things can play out differently: changing weather can cause a body to dry out very quickly or to not dry at all, and if a body is buried, or under water, some kinds of bugs can be prevented from reaching it. Scientists observe bodies in different environments to account for these variables.