There is your DNA and then there is the expression of your DNA. Your DNA if all “gates” are opened is your full potential in body and mind. But parts of your DNA can be switched on and off – epigenetics.
It uses the methyl molecule to get the DNA to wrap around it and hence switch of parts of the DNA that way.
So if there is information that the human brain is not improving with time then it is lifestyle and educations, diet, health etc – any of this could affect our brain, intelligence and state of “being”.
So perhaps there is a bit of slip-sliding back and forth due to epigenetics – today nutter and stupid and tomorrow still nutter but genius.
I am sure Elon Musk still has his bad years and good years and sometimes when he speaks when he is asked a question you would have thought he just got off a spaceship and still learning to speak English.
But generally, I think for most is onwards and upwards.
But, “human brain improving” is not just a matter of only DNA. Perhaps indirectly in this case it might be where things can improve in the way we use our minds. Perhaps our DNA gene expression might change when the brain is used in a more efficient way.
Like this perhaps, from the centre of the silent mind, rather than from the full frontline thinking mind.
Lower and Higher mind spaces:
It is a matter of finding your full potential in body-mind. Your DNA will accommodate anything you ask of it and the DNA will switch on and off according to your needs. You choose what you want and the body-mind will accommodate accordingly. If you choose wrong don’t blame your DNA as it had offered you its full potential but you choose to switch off most of your DNA.