Humans are practically unique as a species in having grandparents who are involved in the lives of their grandchildren.
Research from Basel University and Edith Cowan University in Western Australia has highlighted how crucial the role of the grandparent can be in early life.
Dr David Coall, from Edith Cowan University 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.
Taking care of the grandchildren when the parents are at work, providing financial resources and providing emotional support are just some of the many ways in which grandparents invest in their grandchildren.

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, along with co-author Dr Ralph Hertwig, of the University of Basel, wondered whether the same applied in more westernised societies.
Dr Coall 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.
Now we need disciplines to work together and establish what it is that grandparents do which benefits the development of their grandchildren.
It could be as simple as knowing that there is always someone there if you need them.
The research is published in Current Directions in Psychological Science, a journal of the Association for Psychological Science.