Was cannibalism normal for early humans? Genetic evidence suggests yes:
Mead and colleagues began their investigation by looking at the Fore, an isolated indigenous people who live in the mountains of Papua New Guinea. The Fore, according to oral history, had a custom of consuming their dead at mortuary feasts.The tradition is believed to have begun at the end of the 19th century and persisted until Western settlers abolished the practice in the 1950s. Men ate the best meat, the muscle, while women and children munched the brain.
From approximately 1920 through the 1960s an epidemic of the prion disease kuru swept through the Fore, killing upwards of 200 people a year. One symptom of infection was uncontrollable laughter, which gave the affliction the nickname “laughing disease.”
Women and children were most vulnerable to the disease because they ate the most contaminated parts of the body — the brains. The scientists report that kuru has not been found in any Fore born after the late 1950s.
Mead and colleagues studied Fore women who had participated in the mortuary feasts and found that 23 out of the 30 women they tested had one normal copy of the prion gene and one with the M129V polymorphism, suggesting that those who survived the kuru epidemic had a genetic resistance to the disease.
The researchers then sequenced and analyzed the prion protein gene in more than 2,000 chromosome samples selected to represent worldwide genetic diversity. They found either the M129K or E219K polymorphism in every population.
Based on additional comparisons across cultures and with DNA from chimpanzees, Mead and colleagues estimate the polymorphisms arose more than 500,000 years ago, suggesting that prion diseases were widespread in early human history. The cause of these diseases is unknown, but the researchers suggest cannibalism as a likely candidate.