How did Michelangelo live to be 90 years old during that time?

Actually he lived to be 88. The easiest answer to this is that statistically less than .5% of people lived to that age in 1564, but still there were a few who lived to see the age of 88. read more

His father, Ludovico, lived to be 90 years old, which suggests that Michaelangelo may have had longevity genes from at least one parent. There is evidence that Michaelangelo was likely intellectually gifted as well as artistically gifted. read more

Instead, over the course of the four-year project, Michelangelo painted 12 figures—seven prophets and five sibyls (female prophets of myth)—around the border of the ceiling, and filled the central space with scenes from Genesis. read more

For the Sistine Chapel, Michelangelo fired all of his assistants and painted the 65-foot ceiling alone. read more