Imagine you have two 14 year-old 9th graders One is a nerd, and one is a jock. Both score at the 9th grade level in math.
Then at age 17, in their final year of high school, both are tested again. Once again, both score at the 9th grade level in math.
Now imagine the jock dies, while the nerd survives long enough to finish his final year of high school.
In that final year of high school, the nerd is tested a third time and now scores at the PhD level in math!
The math teacher says “clearly the nerd is genetically smarter. He went from 9th grade to PhD level in just one year, while the jock stayed stuck at 9th grade level for 3 years.”
This is very similar to the logic used to argue that modern humans are smarter than Neanderthals. Steve Hsu writes “What Homo Sapiens accomplished in 50-100k years far outstrips Neanderthal accomplishments over a much longer period of time.”
However modern humans accomplished all this after Neanderthals went extinct, just as the nerd in my anecdote accomplished all his math progress after the jock died. And modern humans were roughly culturally equal to Neanderthals when Neanderthals were alive, just as the nerd and jock were mathematical equals when the jock was alive.
Modern humans and Neanderthals diverged from a common ancestor at the same time, just as the nerd and the jock were born at the same time.
So why then is somehow assumed that modern humans and the nerd accomplished their achievements so much faster than Neanderthals and the jock did?
Perhaps because it’s assumed that modern humans and the nerd did not hit their biological peak until around the time Neanderthals and the jock died respectively. So some think that modern humans were not truly modern humans until 50 kya, while Neanderthals are presumed to have been truly Neanderthals for several hundred thousand years. So even though both species diverged at the same time, when it comes to measuring accomplishments, we start the clock when each species became its true self.
One could make the same argument for the nerd and the jock. Even though both are the same age, the jock likely became a man (hit puberty) around 14, while the nerd did not become a man until 17. And so even though both guys were stuck at 9th grade math from age 14 to 17, the jock had three years of a mature brain to progress, yet stagnated, while the nerd progressed 12 years within a single year of puberty.