Concerns about getting older and fears surrounding declining health may be connected to measurable biological changes ...

The Greenland shark, known formally as Somniosus microcephalus, holds a distinction no other vertebrate can claim: it can live for centuries. These slow-moving predators glide through frigid Arctic ...

When we talk about a biological clock ticking, it usually means the pressure women feel to get pregnant before a certain age. It's linked to the decline in eggs (ova) and fertility as females age.