This indicates insufficient nutrition for most of the population. Famines were common approx. 5-7 years, so if you were one of the small folk, you experienced two to three of them as a juvenile.
And bad nutrition has some effect on brain, too, after all it is part of the body. I do not want to claim that medieval people would be unable to learn calculus, but those with worst food security might struggle.
The flynn effect has slowed down in the western world. This highly suggests not genetic changes but genetic potential being fulfilled thanks to environmental improvements.
And yes, medieval people were as intelligent as modern people. Many of the smartest minds of humanity haven't lived today but hundreds or thousands of years ago. I'd put all behaviorally modern humans are into the same category.
Statements like these only make sense in a narrow context. Unless you're suggesting a dog raised like a human would act more like a human than a dog.
Some of these stories are doubtful and obviously none of them are all that scientific… for one thing why are all the reports from Russia?
> According to Jean-Marc Gaspard Itard, Victor was a normal child at birth[citation needed] but was neglected by his alcoholic parents from an early age.
Hmm. Did they know about fetal alcohol syndrome then? It's suggested he was autistic, which would've been true at birth.
I think FASD is a good guess.
The desperate poor aren’t going anywhere.
Desperate poverty is rapidly disappearing across the world. Look it up!
I doubt we'll figure out how to do genetic reprogramming on people. It seems like patching a few SNPs isn't going to do much.
Our own evolution is slow, but because of our numbers and tech, we're modifying everything around us at an unbelievable pace.
As long as whether you can survive and make children is independent from your gene, Evolution never occurs.
So selection is still around, but nowadays we select for different things than nature used to when medicine wasn't as well developed as it is today.
Note that this selection alone won't cause any genetic change faster than what existed in the past. What really accelerates changes in the gene pool is us deliberately doing them. We'll start with eliminating hereditary diseases, but I don't think we'll stop there. We'll likely study which genetic variants give rise to desirable traits and then make those mutations to upcoming children of interested individuals.