[Izikiel43]

The problem there is with your definition of grandfather. Currently, the age for a grandfather in developed countries is 55+. For most of humanity's history, if there were grandfathers, they would barely make it to 55 years of age.

[saagarjha]

No, plenty of people made it to that age in the past. Life expectancy was significantly depressed by infant mortality.

[Izikiel43]

> in the past

What's "in the past" here? Last 200 years? 500? 1000? In evolutionary scale, those numbers are a blip.