One hypothesis on how early man got the jump on the neanderthals is seafood. Early man took advantage of the sea's bounty, eating shellfish seaweed and fish. The extra omega 3 is thought to have fueled brain development giving them an edge over their large mammal eating cousins.
But maybe its not just the omega 3 that increased the brain power, Iodine may have played a role as well. Iodine deficient populations are associated with increased incidence of goitre, but iodine deficiency is also associated with many different types of mental retardation. in the last century isolated mountain populations with low iodine soils suffered from very high rates of retardation.
Some scientists think that iodine during pregnancy can increase the IQ of the child, reduced iodine intake before 2 years of age is theorised to cause reduced IQ. Iodine deficiency is thought to cause ADD and extreme iodine deficiency is known to cause retardation.
The myth that salt causes all high blood pressure (reducing salt intake can reduce your blood pressure in about 1/3 of people with hypertension, but salts not what caused it. Some individuals have the misfortune to be salt sensitive but this is not the majority of people suffering from hypertension) had led many people to eliminate as much salt as possible from their diet, at the some time this has reduced many peoples iodine intake. New evidence is coming to light that iodine deficiency is correlated with breast cancer, gastric cancer and maybe even chronic conditions like fibromyalgia.
Great sources of iodine include seaweed, seafood and iodised salt. Seaweed is tastier than you think and remember that you need to try a food at least ten times before you decide if you like it! (I read that somewhere
really reputable ;-) for reals!)
So not only does iodised salt make you smart and prevent cancer :-) its damn tasty too!
Eat iodised salt, don't feel bad about it, enjoy it knowing you are getting some damn iodine! If you are not salt sensitive there is little reason to dramatically cut back intake. (All things in moderation off course there no need to start an all brine diet.)
Some references I remembered to bookmark:
Isotopic evidence for the diets of European Neanderthals and early modern humans.
Seafood gave us the edge on the Neanderthals
Iodine Alters Gene Expression in the MCF7 Breast Cancer Cell Line: Evidence for an Anti-Estrogen Effect of Iodine