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IODINE AND AN AGE OLD MYSTERY.

Source: Geographical

Publication Date: 02/01/1999

Author: McWilliam, Fiona


COPYRIGHT 1999 Campion Interactive Publishing Ltd.

A geographer in the US has concluded that Iodine deficiency may have caused many of the distinctive features exhibited by Neanderthals, as well as helping to explain what became of these early hominids. According to Dr Jerome E Dobson, a member of the senior development staff at the Oak Ridge National Laboratory in Tennessee, a single genetic difference -- one that prevented Neanderthals from processing Iodine -- may be all that stands between them and us.

Iodine is essential for modern humans and may have been essential for Neanderthals as well, claims Dobson. Iodine deficiency in modern humans causes goitre, a disfiguring enlargement of the thyroid gland, or cretinism, a worse condition of physical deformity and mental retardation caused also by malfunction or absence of the thyroid gland.

Despite the addition of iodine to table salt in most developed countries, the World Health Organisation estimates that 750 million people suffer from goitre and 5.7 million are afflicted by cretinism. About 30 per cent of the world's population is at risk of iodine deficiency disorders, especially those isolated from the principal sources of dietary iodine like saltwater fish, shellfish and seaweed.

It occurred to Dobson that Neanderthals lived mostly in inland Europe, which is notoriously iodine deficient today and probably was then inhabited by Neanderthal between 230,000 and 30,000 years ago. Writing in the latest issue of The Geographical Review (published by the American Geographical Society of New York), Dobson claims that the bones of Neanderthals are very similar to those of modern humans suffering from IDD. There are, he says, far too many similarities for this to be coincidental.

"Distinctive Neanderthal traits -- overall body proportions, heavy brows, heavy musculature, dental development and propensities for degenerative joint diseases -- are identical to those of modern humans suffering from cretinism," says Dobson. The most striking physical feature of cretins and Neanderthals is bone thickness; in cretins, arm and leg bones stop growing in length but continue to grow concentrically. Skulls are also large and thick.

In modern humans, Dobson explains, hormones in the thyroid gland extract iodine from the food which the body then processes. Maybe, he hypothesises, Neanderthal thyroids were not genetically equipped to remove iodine.

"This implies the genetic difference between them and us may be much less than we had previously thought," he says.

Dobson suggests that the first modern humans, Cro-Magnons, who appeared 40,000 years ago, were able to thrive, because their thyroids were more efficient at extracting iodine. Non-cretinous populations may have appeared in Europe from 40,000 to 30,000 years ago, he says, because some innovation, most likely trade with coastal settlements, introduced iodine to iodine-deficient regions.


COPYRIGHT 1999 Campion Interactive Publishing Ltd.