Jonah Lehrer* points out an exhibition of Paul Ekman's photographs at the Exploratorium in San Francisco.

Ekman is a psychologist at UCSF who has spent time in Papua New Guinea studying the facial expressions of the people there, to try and determine whether or not such expressions are universal, as Darwin suggested in The Expression of Emotion in Man and Animals. 

The exhibition in San Francisco consists mainly of Ekman's photos of the South Fore peoples, a subgroup of about 8,000 individuals who live in the highlands to the east of the island.

In the early part of the last century, a prion disease called kuru was discovered in the South Fore. Kuru means shaking death in the Fore language; it describes the shaky limbs which are characteristic symptoms of the transmissible spongiform encephalopathies.

In the 1950s and 60s, a epidemic of kuru swept through the South Fore, claiming the lives of more than 1,100 people. It was later discovered that this epidemic was associated with the ritualistic mortuary cannibalism practised by the South Fore.

Following the death of a family member, female relatives of the deceased would dismember the body. The muscle would be stripped from the limbs, and the brain and other internal organs removed. Most often it was the women who ate the organs. Hence, the vast majority of victims of kuru were women who had consumed infected brain tissue.

Cannibalism among the New Guinea tribes was outlawed by the Australian government in the 1950s. But recent research shows that there have been 11 cases of kuru in the South Fore during the past decade.

This could mean that small numbers of the Fore continued to practise cannibalism after it was outlawed. Or it could mean human prion diseases have an incubation period of up to 50 years, in which case there is the possibility of a looming epidemic of variant CJD.

*Last week I received a copy of Jonah's book, Proust Was a Neuroscientist, which has just been published by Houghton Mifflin. I'm looking forward to reading, and reviewing it here.