New research reveals that the key to how mankind evolved so quickly is spending time with our grandparents. The unique relationship between grandparents and their grandchildren has given humans an evolutionary advantage, scientists have discovered. 

Researchers at Basel University and Edith Cowan University in Western Australia have highlighted the crucial role of the grandparent in our lives.

Study author David Coall said: ''Evolutionary perspectives on the post-reproductive years have highlighted grandparenthood as an unusual feature of the human lifespan that is only shared with one or two other species, such as some whale species. 

''Grandparents in industrialised societies invest a significant amount of time and money in their grandchildren.'' 

Dr Coall added grandparents can literally help survival by taking care of their young relations when parents are at work, substantially increasing the chance of child living through the high risk period of infancy and childhood. 

He said: ''After examining a large body of evidence from traditional human societies the evidence suggested that the presence of some grandparents can substantially increase the chances of a child surviving during the high risk period of infancy and childhood.'' 

Dr Coall and co-author Dr Ralph Hertwig, also of the University of Basel, wondered whether the same applied in more westernised societies. 

He added: ''Although important effects have been found in traditional societies, there was a paucity of research in Western Nations. 

''We felt if such as association existed in Western societies, where the fertility and childhood mortality rates are much lower, grandparents could make a substantial public health contribution to our society. 

''An integration of evolutionary, sociological, and economic accounts will be necessary to fully explain the impact grandparents have in their grandchildren's development. 

''Grandparents have helped and supported their families in the past, they do now and no doubt, they will in the future.''