In this sense, the trait may enhance comfort levels in intense equatorial climates more than straight hair ( which, on the other hand, tends to naturally fall over the ears and neck to a degree that provides slightly enhanced comfort levels in cold climates relative to tightly coiled hair ).
42.
In areas where there is little iodine in the diet, typically remote inland areas and semi-arid equatorial climates where no marine foods are eaten, iodine deficiency also gives rise to hypothyroidism, symptoms of which are extreme fatigue, epidemic goitre ( swelling in the thyroid gland ), mental slowing, depression, weight gain, and low basal body temperatures.
