When those gender roles are all but constant across countless independently developed cultures existent over tens of thousands of years, with distribution of visible physical traits to match them, it's pretty safe to assume that they're baked into our DNA and not some random whim of western culture.
Imagine how long a tribe with male caretakers and female warriors (who it cannot be argued are not on average significantly smaller and weaker than men) would survive against a tribe of male warriors and female caretakers.
There are species with much less divergence in biology between males and females. We would not have evolved to have such divergence if it were not useful for our fitness to have distinct fighter/protector and caretaker roles. Indeed as K-strategists that take a very long time to mature, having dedicated caretakers was an extremely useful evolution.
Imagine how long a tribe with male caretakers and female warriors (who it cannot be argued are not on average significantly smaller and weaker than men) would survive against a tribe of male warriors and female caretakers.
There are species with much less divergence in biology between males and females. We would not have evolved to have such divergence if it were not useful for our fitness to have distinct fighter/protector and caretaker roles. Indeed as K-strategists that take a very long time to mature, having dedicated caretakers was an extremely useful evolution.