Certain words in the English language come with an "ick factor" attached. One of those is: cannibalism.
It's just not something we like to think about, at least for our species: eating others of our own kind (except in zombie movies).
But cannibalism is not unusual in nature, and may actually serve a purpose.
Zoologist Bill Schutt explains in his book Cannibalism: A Perfectly Natural History. He gives us the whole picture, from smaller organisms up to the Donner party. Dr. Schutt visits with highlights.