For want of iodine
THE fossil record of Neanderthals
abruptly ends about 30,000 years ago.
Why Neanderthals suddenly went
extinct is a topic of much debate even
today. Some experts suggest that they
may have lost a "fight" with the more
tech nologically- advanced Homo sapiens sapiens, while others say interbreeding with them diluted their characteristics. Over the ages, there have been
many more explanations.
Jerome Dobson, a geographer at the
Oak Ridge National Laboratory in
Tennessee, USA, offers yet another explanation. He claims to have found evidence suggesting that the cause of their
extinction may have been iodine. The
skeletons of Neanderthals bear signs of
physical deformities and possibly
impaired mental health, says Dobson.
According to him, an iodine-deficient
diet may have been responsible for the
physical differences between the
Neanderthals and the modern humans.
The findings suggest that
Neanderthals could have been anatomically similar to modern humans. But
what made them different from modern
humans is a history of iodine-deficiency
diseases, like cretinism. In modern
humans, an iodine- deficient diet may
lead to goitre, an enlargement of the
thyroid gland. Worse still, it may cause
cretinism which leads to physical and
mental retardation because of the failure of the gland to develop.
According to the World Health
Organisation, at present, about 750 million people suffer from goitre and 5.7
million people are cretins around the
w0f1d. It is estimated that 30 per cent of
the world's population is at risk of
While ex-amining the differences
between coastal and inland populations,
it struck to Dobson that Neanderthals
mainly inhabited iodine- deficient areas
in interior Europe. He examined 300
Neanderthal skeletons in museum collections around the world and compared them to 17 cretin skeletons in
Basel, Switzerland, and Philadelphia,
USA. A careful study of the skeletons and
medical descriptions revealed too many
similarities, says Dobson. For instance,
cretin& had bulging brow ridges like the
Neanderthals. Similarly, they seemed to
suffer from many degenerative joint diseases that afflicted the Neanderthals too. Thus, he concluded that iodine made all
the difference in Neanderthals' physical
and mental being.
Dobson's analysis leaves open two
theories for experts to probe into: continuity or replacement. The former suggests that the Neanderthals may have
they changed their diets to include more
iodine-rich foods and certain
Neanderthal physical traits did not persist though qieir genes continued into
later European populations.
The replacement theory suggests that "iodine deficiency among
'Neanderthals may explain why they were so easily replaced by Cro-Magnons", modern humans who
arrived in Europe 40,000 years ago.