A long time ago I saw the following quote:
CAESAR (recovering his self-possession). Pardon him. ... he is a barbarian, and thinks that the customs of his tribe and island are the laws of nature.
That is from George Bernard Shaw's play Caesar and Cleopatra.
After tracking down the quote, I opened the play to see it in context. I will probably be reading the whole play soon; it looks like an excellent work.
The reason I was reminded of this quote was this article. An economist studied two tribes in rural India with almost identical genetics, wealth, and living conditions, but very different cultures. This is almost a perfect natural experiment, so I expect these two tribes to be studied a lot more in the future.
One of the tribes is patrilineal. Women are not supposed to own land, and the oldest son inherits the property. The other is matrilineal. Property is inherited by the youngest daughter, men are not allowed to own land, and any earnings of the male are supposed to be handed over to his wife or sister.
They had the villagers do a simple puzzle-solving test. In the patrilineal tribe, the men did better than the women. In the matrilineal tribe, there was no statistically significant gender gap. What is even more in interesting to me is a fact that was not mentioned in the Time article: The men in the matrilineal tribe actually did better than the men in the patrilineal tribe:
Here is the actual academic paper, which may be gated. If you can open it, do so, because it is full of fascinating details that the news articles left out. If you have any unanswered questions after reading the popular article, as you should, head over to the actual scientific article.
Note that this study, like most good science, is a small bit of knowledge. It tells us about one particular mental ability. More studies are needed to test other abilities. But it is still very important. It provides evidence that the 'gender gap' in math and spacial abilities could easily be due to culture rather than genetics.
I have not seen anyone speculate on why the men in the female-dominated culture actually did better than the men in the male-dominated culture. The men in the patrilineal society actually had more education, and education was correlated with faster problem solving.
Keep this study in mind whenever people talk about 'innate' ability differences between groups. The customs of our tribe are not laws of nature.