The miracle of mummification is how a body buried nearly 5,000 years ago could remain intact, while a non-mummified body decomposes into a pile of dust in just a few hundred years. The key is desiccation – removing all moisture from the body and storing it in an extremely dry environment. Bodies rot because bacteria thrive in the moist conditions of decaying flesh and organs. Bacteria can’t live, however, where there is no water. In Ancient Egypt and South America, the first mummy-making cultures probably found animals whose skin remained intact after dying in extremely dry places – both hot and cold. To replicate this process, Egyptians removed all of the deceased’s internal organs and coated the body inside and out with a salt mixture. After 40 days or more, the salt would have drawn all of the moisture from the body. Organs were dried separately and either placed in urns or back inside the body. Mummies were also stuffed with sawdust before being treated with naturally antibacterial oils and wrapped in layer upon layer of sticky resin and linen. Mummification didn’t always work, but if the body was fully dried, carefully wrapped and stored in a perfectly dry place, the skin and bones would remain preserved for millennia.
Answered by Dave Roos.