This is Scientific Americans 60 Second Science.

I'm Karen Hopkins.

Living with your parents has its benefits,

at least when it comes to raising your kids,

they are grandkids. Because two new studies add to the evidence

that grandmothers can enhance the survival of grandchildren.

That is, unless grandma's too old or lives too far away. The results appear in the journal

Current biology. Humans are unusual and that the females live long past the age

at which they stop having babies. We don't really see that in nature.

Most of the organisms will reproduce up to their very last moment.

Patrick Berjon, Professor of Biology at Bishop's University in Quebec.

This increase in post-reproductive longevity is often explained by the so-called

Grandmother Effect. Because family members share their genes, there could still be a

benefit for postmen oppose a woman to increase their genetic footprint by helping

their daughters to rear larger families. To explore the Grandmother

effect hypothesis, Berzon and his colleagues examined nearly 200 years

worth of French Canadian population records from the 17th and 18th centuries.

At the time life was tough. In some years, a third of the kids were not even making it to one year of age.

But the researchers found that having a grandmother still alive was a definite plus.

Families with grandmother's live were larger by about two and the survival of these grandchildren to age 15 was much improved.

This beneficial effect was only seen when the matriarchs lived nearby, which suggests that grandmothers

help by playing an active role in their grandchildren's lives.

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