I feel like this is one of those situations where people distort a 45:55 into either a 0:100 or a 50:50.
Ecologically speaking, we're a lot like megafauna rats: we thrive from adaptability. Throw humans into whatever environment, with access to whatever barely edible junk, and they'll still survive and reproduce. As such you expect selective pressure against built-in specialisation of the individuals, for two reasons:
- kin selection - if depending on the environment half of your tribe is dead weight, you're all going to die.
- individual survival - we might be a social species, but we can't always rely on other people.
However that does not mean that you should expect the exact same proficiency for all individuals on all tasks based on their innate attributes, such as sex. Some might be really good hunters but passable gatherers; some, the opposite. And I believe that this applies in special to the [important!] typical man and the typical woman.
I can't emphasise "typical" enough. Because even when dealing with individuals of the same sex, you will see some difference in ability towards certain tasks.