Researchers at Edinburgh University have produced a new study which questions the fundamental assumptions of human evolution.

Key dates in the development of mankind - including the age of "Eve", the last common female ancestor - may be wrong.

It has long been accepted that a type of DNA - the chemical containing the genetic blueprint for each living thing - was passed down through our mothers.

But the researchers now believe the biological structure may contain our fathers' genes too.

DNA in the mitochondria - the element which powers cells - had been thought to contain genetic information only from the mother's side.

The Edinburgh team - working with colleagues at the University of Sussex - say their studies of humans and chimpanzees suggest mothers' and fathers' genes may in fact mix in mitochondrial DNA.

Until now researchers have used such DNA to trace the lineages of humans and other organisms back though time - and to set key dates in human evolution.

The university study now suggests humankind may have to think again about assessing how old it thinks we are.