This got me thinking - is there any reasonable metric we could use to measure the intellectual capabilities of the most capable species on Earth that had evolved at each point in time? I wonder what kind of growth function we'd see.

Silly idea - is there an inter-species game that we could use in order to measure ELO?

Except it is sublinear. Sonnet 4 was 10.2% above sonnet 3.7 after 3 months.

We should all know that in the software world, the last 10% requires 90% of the effort!

Sublinear as demonstrated on a sigmoid scale is quite fast enough for me thank you.