At a family gathering, an outdoor picnic, the conversation turns to cicadas, the 2024 co-emergence of both the 17 and the 13 year broods. My sister-in-law says "gee, wonder when that last happened?" My brother (Georgia Tech math major) responds: "um, that would have been (calculating in his head) 1803." She just stares at him. "They're prime numbers" he adds, goes back to his grilled chicken . . . . .
(I add nothing about why evolution led to the prime numbers . . . . it was a family gathering with churching going family members)