Most male fin and blue whales sing at around 17 to 18 hertz, which is too deep for humans to hear, but the 'lonely' whale communicates at 52 hertz. When more recordings were released in the nineties, Dr Watkins studied the 52 hertz whale more closely.
The average person needs to absorb just a small amount of iron each day to stay healthy (around 1 mg for adult males and 1.5 mg for menstruating females). To achieve this, however, we need to consume several times that amount. This is because our bodies absorb only a fraction of the iron contained in the foods we eat.
Recommended Dietary Allowance. Daily iron requirements fluctuate according to age. University of Maryland Medical Center reports that infants 7 to 12 months old need 11 milligrams of iron a day. Babies from 1 to 3 years old only require 7 milligrams; the amount jumps to 10 milligrams for children ages 4 to 8.