Dogs have been a loyal companion to mankind for more than 30,000 years, findings reveal.

Scientists believe that two 33,000-year-old skulls unearthed in digs in Siberia and Belgium show dogs were domesticated long before any other animal, such as sheep, cows or goats.

Researchers from the University of Arizona said the skulls had shorter snouts and wider jaws than undomesticated animals such as wolves, which use their longer snouts and narrower jaws to help them hunt....