Many of the people that will contribute to it have already been born, so short of some catastrophe that kills off large numbers of people, or some Viagra-fuelled leap in birth rates, population numbers and age composition can be predicted with fair accuracy for decades ahead.

ECONOMIST: Demographics: Greying globe | The

Using a combination of modern physics tools--including three-dimensional, high-resolution X-ray, radiocarbon dating with accelerator mass spectrometry, and infrared spectroscopy--the researchers analysed the tooth to determine the age and composition of a resinous filling detected inside.

UNESCO: Basic Sciences

That's because the sound they make depends on their age, size and chemical composition.

BBC: Team records 'music' from stars

"A lot of coaches treat all the players the same way, whatever their age, whatever their body composition, whatever their injury history, whatever their playing position - everybody is doing the same training, " Verheijen said.

BBC: Total fitness from the land of Total Football

But the 22-year-old Brit, who started writing music at age 4, also studied composition and violin at the prestigious Guildhall School of Music and Drama and wrote a piece for the London Philharmonic Orchestra last year.

NPR: Micachu And The Shapes: Kitchen Sink Music

But no definitive study has been published showing whether these small changes in body composition are enough to truly slow age-related declines in physical performance.

FORBES: Sweet Syringe of Youth