Have you thanked your grandma today? You might want to consider it. A recent study found that kids live longer when a grandmother takes part in their daily lives.  Most animals die soon after their childbearing years are over. Women, however, often live for many years after they stop having kids.   To try to understand why, researchers from Finland looked at birth and death records of two communities from the 18th and 19th centuries, one in Finland and one in Canada. In these communities, 537 Finnish women and 3,290 Canadian women were grandmothers who had lived past the age of 50.    For every decade they lived beyond 50, the researchers found that the women ended up with an average of two extra grandkids. It didn't matter what the differences in health or living conditions were between the two communities or from family to family.   Grandchildren were also more likely to live into adulthood if their grandmothers were alive when they were born. If their grandmothers were younger than 60 at the time, that was even better. The study also found that women had children 2 to 3 years earlier if their own mothers were still alive at that time than those whose mothers had died.    The researchers suggested that grandmothers have provided important assistance in raising their grandchildren for at least the past 200,000 years. As a result, they helped extend everyone's lifespan.    So, don't take your grandma for granted! According to the passage, we don't know that   _  .
kids live longer when grandmothers take part in their daily lives most animals die soon after their childbearing years are over women often live for many years after they stop having kids grandchildren are less likely to live into adulthood if their grandmothers are alive