The social stigma against cannibalism has been used as an aspect of propaganda against an enemy by accusing them of acts of cannibalism to separate them from their humanity. The Carib tribe acquired a longstanding reputation as cannibals following the recording of their legends by Fr. Breton in the 17th century. Some controversy exists over the accuracy of these legends and the prevalence of actual cannibalism in the culture.
According to a decree by Queen Isabella of Castile and also later under British colonial rule, slavery was considered to be illegal unless the people involved were so depraved that their conditions as slaves would be better than as free men. This legal requirement may have led to conquerors exaggerating the extent of cannibalistic practices, or inventing them altogether, as demonstrations of cannibalistic tendencies were considered evidence of such depravity.
The Korowai tribe of southeastern Papua could be one of the last surviving tribes in the world engaging in cannibalism.
Marvin Harris has analyzed cannibalism and other food taboos. He argued that it was common when humans lived in small bands, but disappeared in the transition to states, the Aztecs being an exception.
A well known case of mortuary cannibalism is that of the Fore tribe in New Guinea which resulted in the spread of the disease Kuru. It is often believed to be well-documented, although no eyewitnesses have ever been at hand. Some scholars argue that although post-mortem dismemberment was the practice during funeral rites, cannibalism was not. Marvin Harris theorizes that it happened during a famine period coincident with the arrival of Europeans and was rationalized as a religious rite.
In pre-modern medicine, an explanation for cannibalism stated that it came about within a black acrimonious humour, which, being lodged in the linings of the ventricle, produced the voracity for human flesh.
Some now discredited new research got a lot of press attention when scientists suggested that early man may have practiced cannibalism. Later reanalysis of the data found serious problems with this hypothesis. According to the original research, genetic markers commonly found in modern humans all over the world suggest that today many people carry a gene that evolved as protection against brain diseases that can be spread by consuming human brains. Later reanalysis of the data found a data collection bias, which led to the erroneous conclusion.