The popular image of a Neanderthal is that of a hunched ape-like creature with its knuckles scraping through the dirt.

New research, however, reveals they stood more upright than modern humans.

The first scientific comparison between current day homosapiens and neanderthals shows mankind’s ancient cousin had a straighter spine and stronger lungs.

Based on the most complete skeleton unearthed to date, it conjures a radically different image to the stooped and barrel chested character of myth.

The new research also adds to growing evidence the mysterious species was far more sophisticated than previously assumed and may finally reveal why it died off.

Unlike humans, the ribs connected to the spine in an inward direction - forcing the chest out.

This made them tilt slightly backwards, with little of the forward curvature of the lower or 'lumbar' vertebral column that is unique to humans.

Anthropologist Dr Markus Bastir, of the National Museum of Natural History, Madrid, said: "The differences between a Neanderthal and modern human thorax are striking."

The thorax includes the rib cage and upper spine which forms a cavity to house the heart and lungs.

Lead author Dr Asier Gomez-Olivencia, a palaeontologist the University of the Basque Country, Bilbao, said: "The Neanderthal spine is located more inside the thorax, which provides more stability. Also, the thorax is wider in its lower part."