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 average daily iron intake from foods and supplements is 13.7â15.1 mg/day in children aged 2â11 years, 16.3 mg/day in children and teens aged 12â19 years, and 19.3â20.5 mg/day in men and 17.0â18.9 mg/day in women older than 19.