Cannibalism is rare nowadays, but it still exists. If you have been following the news, there have been reports from time to time of people being suspected of committing human cannibalism.
Even until the late 18th century, human cannibalism is being practiced in some areas in the modern world. Hostility toward the practice later became widespread and effective. Still, in some areas and cultures practicing cannibalism continue to exist.
Modern science, however, suggests that humans are not actually good food for our own species. Diseases can spread more readily, with some being particularly gruesome. Prion diseases, for instance, are thought to have inflicted prehistoric cannibals.