Think of the Day.
I wonder whether there's a reason genetics seems to skip a generation. Like, for the longest time, the average life expectancy was 40 years or so. If a trait skipped one generation, then you'd be, statistically, sure to get necessary traits all the time, without doubling up. A shoemaker begets a poet, who begets a shoemaker, who begets a poet--that way, you always have a poet and a shoemaker available, without redundant shoemakers or poets.