A Wellington anthropologist who single-handedly destroyed the reputation of American "Earthmother" Margaret Mead, one of the 20th century's towering intellectuals, has himself been accused of being obsessive, a bully and, worst of all, faking his key evidence.

Derek Freeman, who died in 2001 aged 85, won international attention in 1998 with his book The Fateful Hoaxing of Margaret Mead in which he claimed there was never "another example of such wholesale self-deception in the history of behavioural sciences".

It was argued that teenage Samoan girls tricked Mead into believing they led relaxed and sexually free lives. She had been hoaxed as the result of her youth, gullibility and lack of knowledge of Samoan culture, Freeman said.

Mead's 1928 best seller, Coming of Age in Samoa, was the most widely read anthropology book for decades and in the United States was key to debate on family, adolescence, gender, social norms and attitudes.

Freeman's critique was widely accepted and destroyed the reputation of Mead, who had died in 1978 aged 77. It also left the study of anthropology badly savaged.

Now some remarkable detective work through Freeman's own papers reveals it was he who was hoaxing the world.

Freeman had found an 86-year-old woman, Fa'apua Fa'amu, whom he described as Mead's key informant 50 years earlier, along with another girl, Fofoa. He had her swear on the Bible that when she had told Mead "we spend the nights with boys" she was joking.

"That a Polynesian prank should have produced such a result in centres of higher learning throughout the Western world is deeply comic," Freeman claimed.

"Never can giggly ﬁbs have had such far-reaching consequences in the groves of Academe."

Enter Paul Shankman of the University of Colorado-Boulder, who now says a study of Freeman's own records, and those of Mead, shows Fa'amu and Fofoa were not part of Mead's original research on sex.

In a piece in the latest issue of Current Anthropology published by the University of Chicago, Shankman says Fa'amu had told Freeman she was never questioned by Mead about her own sexual conduct or about adolescent sexual conduct.

Freeman, who was educated at Victoria University, had manipulated her quotes.

"Crucial passages from these interviews were omitted by Freeman in his publications on the alleged hoaxing."

Less than a page from more than 140 handwritten pages of interview material was used by Freeman.

Shankman said that if other scholars had access to the interviews, Freeman's book would never have seen the light of day.

He told the Sunday Star-Times that Freeman had selectively quoted a section of the interview that appeared to support the hoaxing of Mead, but he omitted Fa'amu's denial that she had discussed her own sexual conduct with Mead.

"Freeman used Fa'amu's testimony for his own purposes. Mead cannot have been fooled by women who were never her informants. She had actually collected data from 25 adolescent girls of whom over 40 per cent were sexually active."

Mead did not get Samoa exactly right - she plainly downplayed the scale of rape and violence - but nor did she invent a false culture, as Freeman claimed.

"Regrettably, Freeman's ﬂawed caricature of Mead and her Samoan ﬁeldwork has become conventional wisdom in many circles and, as a result, her reputation has been deeply if not irreparably damaged. And this is no joking matter."

The result of Freeman's critique was deep and irreparable damage to her reputation.

"Freeman trashed Mead's reputation in a deliberate and personal manner."

When his book came out Freeman claimed it was "the greatest denouement in the history of anthropology so far, not excepting Piltdown man".

In responses to Shankman, sociologist James Cote of the University of Western Ontario says the only remaining curiosity is why Freeman had left evidence in his own files "that is so damning to a legacy that was apparently important to him".

Cote said Freeman's errors have finally been expunged.

"It remains to be seen how long it will take for Mead's reputation as an ethnographer to be restored."