You mean you're not convinced. — L'éléphant
There are two questions here:
One is: Were hunters / gatherers smarter than us, or not?
Two is: Can we determine the answer to question One?
Answer One: I don't know; nobody else does either.
Answer Two: We can not.
At a distance, I don't have a reliable, valid way of measuring
your intelligence. I would need to be present with you, administer tests, and observe your performance. I would need to interview you, take a personal and family history, etc. For a much less robust measurement, I could have someone administer a paper and pencil test to you.
Let's try going back in time to... 1900. Let's measure the intelligence of your ancestor. You choose. I will assume the person is dead. How would we measure his or her intelligence?
Let's go way back to 15,000 B.C.E. The time machine is broken so we will have to measure the intelligence of someone ??? far away in time and space. How would we measure his or her intelligence?
to continue saying "we don't know..." and "we have no way of knowing.." are killers of rational dialectic. — L'éléphant
Not so! There is nothing wrong or irrational about saying "We don't know" when, in fact we do not know, and in fact there is no way to know.
What we can and do know about our hunter / gatherer forebears is that
a) they survived the difficulties they faced (we know, because we descended from them)
b) they were very good tool makers (we know because many of their stone tools survived)
c) they had a culture for which they left very few traces, except cave paintings and many stone tools. (We know that fabric and wood tend to not survive in the environment for long. We have seen the caves, and have collected the stone tools.)
d) they were successful in their lives (their skeletons show that they were generally healthy and strong
When you reach the end of what you can currently know, it is appropriate to claim no more knowledge.
Future research may reveal more about our distant forebears. I will quote Wittgenstein here: "Whereof one cannot speak, thereof one must be silent." Topics like "The nature of God" are examples about which we should remain silent.
We certainly can and will speculate about what we MIGHT know in the future. That's fine as long as we don't claim our speculation as fact, until it IS fact, which it might never be.