For a long time, biologists could hardly explain the existence of grandmothers: Older women can no longer give birth to offspring after the menopause, they are theoretically unimportant for the preservation of the species - and possibly a burden for the family.

In recent years, this mystery has been partially solved.

A look at the animal world helped: With orcas and elephants, i.e. animal species that live in families with several generations and where females are in charge, grandmothers are very important for the groups.

Pia Heinemann

Editor of Nature and Science

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Orca grannies look after the young animals and promote their survival by sharing their prey and teaching hunting strategies.

The offspring of elephants with grandmothers also have a higher chance of survival.

The old females also help the group by relieving the younger ones so much that they become fertile earlier: Overall, they have more offspring than elephant cows without grandmothers in the group.

The old female elephants also pass on their wealth of experience. They know, for example, where waterholes can be found even in times of drought or in which areas it is too dangerous because poachers are hanging around there.

Grandmothers – and increasingly also grandfathers – relieve the pressure on the nuclear family, especially when both parents work.

There are not many studies on whether they also promote the health of the family.

These are often small and of more anecdotal value.

However, it is obvious that grandparents who help with childcare bear a certain responsibility.

A cross-sectional study conducted two years ago by health researchers at the Massachusetts College of Health Sciences in Boston shows, for example, that the knowledge of grandparents affects the dental health of grandchildren: the less educated the grandmothers and grandfathers were, the more tooth decay the grandchildren had.

In the study, many grandparents did not know, for example, that fruit juice in a feeding bottle promotes tooth decay and that periodontal bacteria can be transmitted through shared toothbrushes and tumblers.

A small study by the Karolinska Institute in Stockholm shows that children who are cared for by grandparents are less likely to be overweight than those whose grandparents have no influence on their children's nutrition.

Here, too, the education of the grandparents is crucial.

That's why they should keep up to date on the status of nutritional research - and also know which nutritional trends are currently prevailing among the grandchildren, whether sugary bubble tea or smoothies are popular or what vegan nutrition means.

A Scottish study showed that some grandparents tend to serve traditional, high-fat and high-carb dishes.

The researchers therefore demand that grandparents should always be aware of their influence on the health of their grandchildren and not underestimate it.