Are Tasmanians inbred? Surprising origin of two-headed Tasmanian joke

May 2024 · 3 minute read

For as long as any of us can remember, Tasmanians have had to put up with jokes about inbreeding due to the state’s small and isolated population.

But the most solid theories about the source of the “two heads” jibe have nothing to do with a small gene pool.

University of Tasmania history professor Stefan Petrow says the joke has coloured the way the rest of Australia views the Apple Isle.

“It’s so strongly ingrained in any joke about Tasmania that it often comes up,” he told the ABC.

Inspired by a question from a curious reader, the news outlet set out to discover if there was any truth to the two-headed myth and came across some fascinating possible explanations.

One was an anecdote from World War I that involved soldiers from Tasmania apparently requesting two pillows for their bunks instead of settling for one like everyone else.

“I haven’t come across that particular point, but it’s not impossible,” Prof Petrow said.

“Tasmanians were mixing more directly with Australians from other states during the course of the war, so it’s certainly possible, but I’d love to see some hard evidence.”

But the most plausible explanation is the state’s iodine deficiency problem.

During the Ice Age, the island’s topsoil was stripped of the mineral, leading to widespread cases of goitre in the 19th and 20th centuries.

Iodine is essential in the prevention of goitre, a condition involving the enlargement of the thyroid gland, causing the neck to swell to unsettling proportions — giving the impression of a second head.

“There was a tremendous amount of goitre in Tasmania,” Professor of nuclear medicine Paul Richards told the ABC.

“It was just taken for granted that you had a goitre.”

It was so common even Tasmania’s most famous political pioneer, Dame Enid Lyons, was a sufferer and had her goitre surgically removed in time for the 1949 federal election.

Her case may have prompted a public health campaign launched the same year in which the state government handed out daily iodine potassium tablets to schoolchildren.

However, in trying to correct the iodine balance, authorities went too far, with a proliferation of iodine supplements leading to an epidemic of thyrotoxicosis — hyperthyroidism caused by the overproduction of hormones.

Prof Richards, who is now retired, worked with thyrotoxicosis sufferers at the height of the problem and said while the correct balance had finally been achieved, the tipping point was never far away.

“Iodised salt in bread is now mandatory, and iodine is a key ingredient in the products used to clean milk vats and cows’ teats before milking,” he told the ABC.

“But all the dairy companies have to do is switch to a chlorine-based cleaning product, and we’ve got the same problem all over again.”

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