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.
The US National Research Council currently recommends that females between the ages of 11 and 50 intake 15 milligrams of iron daily. The iron intakes of a random sample of 25 such American females are found in the dataset irondef.txt.