Speculation a middle-aged Pakeha woman wandered the Wairarapa region decades before Captain Cook discovered New Zealand has been rejected by experts.
Anyone living in the Featherston area in the mid-1700s would likely need to have travelled to Indonesia to find a woman of European descent, Richard Hill of Victoria University said yesterday.
Professor Hill admitted to being "sceptical" of claims a human skull found on the banks of the Ruamahanga River - southeast of Featherston - dated from at least 1742, and was that of a European woman aged about 45.
Carbon dating in 2005 put the skull's age at 296 years - plus or minus 34 years - and forensic pathologists judged it probably to be European.
Its age, if genuine, would mean the woman had found her way to New Zealand some 25 years before Captain James Cook's arrival in October 1769.
There were no regular visits by European vessels at least until the late 18th century, Professor Hill said.
The first two white women to come to New Zealand were escaped convicts Kathleen Hagerty and Charlotte Edgar, who arrived from Australia in 1806.
Following Abel Tasman's first sighting of New Zealand in 1642, there was little evidence of other ship visits until "the great age of exploration" around the time of Captain Cook.
"(There is) no evidence that I have ever heard of any Pakeha women in New Zealand at that time," he said.
Massey University historian James Watson said there were a number of European powers with interests in the wider region by the 1740s, but economic priorities meant they focused on areas such as Indonesia, Micronesia and China - not the Featherston region of New Zealand.
"It would be unusual to be this far south - unprecedented."
Dr Watson's colleague Kerry Howe said though there was "no evidence at all" for European settlement in New Zealand until the late 18th century, conspiracy theorists would be "delighted" to hear of the possible arrival of Europeans before Cook.
He believed the skull should be retested and the carbon dating equipment checked. The only other possibility was the skull has been dropped by a later settler.
Professor Howe - whose book The Quest for Origins: Who First Discovered and Settled New Zealand and the Pacific Islands? deals with numerous Pacific immigration theories - said while it was impossible to say definitively that there were no Europeans here before Cook, there was no supporting evidence found with the skull to say how it got there.
The skull is being housed in Masterton's Aratoi Museum.