Thanks to the anonymous moonman for finding Lord Baron King-Man Michael Woodley of Menie’s JewTube:
tl;dr- Human genetic intelligence has been trending upward for 10,000 years or so, probably due to the positive feedback effect of navigating and creating increasingly complex cultures, and statistically we can be pretty certain of this.
Please note: It would be misrepresentative to imply Woodley believes this remains true in the last 150 years. On the contrary, he believes we’re in a period of precipitous dysgenics where the Flynn Effect is explained by the co-occurrence model (i.e. cultural momentum producing excellent soil as average seed quality worsens via relaxed selection).