The argument has been made that gender is fully a social construct, with no biological merit. I want to argue against this point. First, I do acknowledge the fact that there are obvious cultural artifices in constructing how the two sexes behave. Pink is often associated with girls, while blue is typically linked to boys. Ashley is a girl’s name, and John is a boy’s name. These are all examples of gender norms established by society. But there is also a certain predisposition that is fully biologically based. Point one, men and women have varying degrees of hormonal differences. Men, on average, have far higher levels of testosterone than women, and women, on average, have far higher levels of estrogen. Our emotions and behaviors are heavily influenced by the chemicals in our brains. For example, higher levels of testosterone lead to a higher instance of aggression, assertiveness, and violence. Estrogen makes individuals more empathetic. The unequal distribution of these two chemicals among the sexes leads to differences in biological dispositions and behavior.
Many point out how Gender roles are socially based. But I want to argue that gender roles are a part of human evolution. Humans are a sexually dimorphic species, meaning there is a physiological difference between the sexes. Men are on average 3 inches taller and weigh 25% more than women. Nature doesn’t just make species sexual dimorphic unless there are some sexual survival benefits from it. Case in point, a book written by Leonard Shlain “Sex, Time, and Power”(A must read) Shlain( a surgeon) theorizes that because women on general suffer from Iron deficiency(due to the fact they lose blood every month from menstrual cycles, as well as their red blood cells produce less Iron), and the fact women have to go through eight months gestation and six years weaning a newborn child. Women needed men to help them attain Iron by providing them with meat; in return, the men got copulation.
For those (particularly feminists) who are skeptical about this. Imagine 150,000 years ago, living in the Savannah of East Africa, being a pregnant mother (let’s imagine 6 months), trying to go hunting. You would put yourself and your child at great risk. Sure, you would be able to go forging, but subsisting on local vegetation alone will not be enough for you and your gestating child. Men would have to go out and hunt while the women remained in the village. This arrangement would have existed for all of humanity until the emergence of civilization around 10,000 years ago.
With the beginning of civilization, humans transitioned from relying solely on wild game and vegetation to domesticating both crops and animals. Many of the roles that women had previously held remained largely unchanged, as women still became pregnant and had to care for their young children. Men now had to participate in the field or face starvation. We see the emergence of patriarchy in this time period. Men, having a physical advantage over women, took responsibility for keeping society safe from outsiders as well as undertaking all the intense labor required for agriculture.
Feminism as we know it wouldn’t become a serious ideology in Human affairs until the Industrial Revolution, for good reason. Humanity (at least in the West) wasn’t reliant on muscle power, but on stem and steel to grow its food. Women could go out to work. This new era of technological advancement is the only reason feminism was able to emerge!
Da Joanis Project 
It seems as if you’re appealing to evolutionary psychology for a simple explanation, yet are determined to ignore what actual psychologists and qualified experts have to say about the issue: that gender is a social construct.
You make this point yourself that gender roles are dependent on times, society and the needs of that society at that point in time:
> For those(particularly feminist) who are skeptical about this. Imagine 150 thousand years ago, living in the Savannah of East Africa being a pregnant mother(let’s imagine 6 months) trying to go hunting. You would put yourself as well as your child at great risk. Sure you would be able to go forging, but subsisting on local vegetation alone will not be enough for you are your gestating child. Men would have to go out and hunt while the woman remained in the village. This arrangement would exist for all of humanity until the emergence of civilization around 10 thousand years ago.
> With the beginning of civilization, humans moved away from solely surviving on wild game and vegetation but to domesticating both crop and animals. Many of the roles that woman had previously still remained somewhat the same, because women still got pregnant and had to attend to her young children. Men now had to attend to the field are face starvation. We see the emergence of patriarchy in this time period. Men having a physical advantage over women, took responsibility of keeping the society safe from outsiders as well as seeing to all the intense labor required for agriculture.
This ignores the societies where women and men did the same labor. Resources were pooled and aloted such that it wasn’t a problem if a pregnant woman needed to rest or work less.
> This new era of technological advancement is the only reason feminism was able to emerge!
It is regularly argued that the industrial revolution, a shift from subsistence existence on communal lands to wage labor and the free time gained from the subsequent battles labor waged is responsible for much of the way we now think about and relate to each other. Modern identities have developed in a climate where tribal relations have eroded into economic ones, where labor is alienated from its product and the social constructs and roles that were necessary in the past have been bulldozed in favor of individualism.
Using your line of reasoning, one could de-legitimize a homosexual or bisexual identity as being the product of a new era of technological advancement, because those identities have only reared their heads in post-industrial revolution societies for reasons listed above. In the past, one entered a marriage with the opposite sex arranged by one’s family or tribe despite sexual orientation because the unit of survival was a family with enough children that could make subsistence existence viable. It was only later, after capitalism became the mode of production and trade, that the concept of dating entered society and identities formed on the basis of sexuality emerged.