These conclusions only apply to the tropics where you have no seasons are very little seasons and where the loose tropical soil can be easily maintained with hoe agriculture by the women... Up north in Europe where you have harsh Winters where the soil is hard and thick and where it must be plowed requiring strength and so forth, it's an entirely different story. Better notice the author did not say this did not mention this comparison. I wonder why
This article is about the Paleolithic era, before agriculture was developed.
Also, hoe vs plow agriculture tended to do with the availability of domesticated draft animals, not the hardness of the soil. The first plows appeared after oxen were domesticated in Mesopotamia. This did have an effect on the gender distribution of agriculture, not because women couldn't use hoes, but because they couldn't handle plows driven by draft animals.
