The molecular structure of DNA was first determined by Watson and Crick in 1953.

Without its lining of mucus your stomach would digest itself.

Neutron stars are so dense that a teaspoonful would weigh more than all the people on Earth.

Female black widow spiders eat their males after mating.

Englishman Roger Bacon invented the magnifying glass in 1250.

Giraffes often sleep for only 20 minutes in any 24 hours. They may sleep up to 2 hours (in spurts - not all at once), but this is rare. They never lie down.

Christian Barnard performed the first heart transplant in 1967 - the patient lived for 18 days.

When Krakatoa erupted in 1883, its force was so great it could be heard 4,800 kilometres away in Australia.