What you do not see is animals going against their instinctual behavior often, because their brains are not sophisticated enough for reasoning and complex choices. That is not the case for human beings, however.

[Citation needed]

You're seriously underestimating the capacity of non hoomin animals to disobey instinct. Or overestimating hoomin capacity thereof. Or both.

Yet human behavior patterns and choices have most often followed a variety of environmental factors, rather than proving immutable.

And then environment becomes genetics. Lactose tolerance, alcohol tolerance, vitamin D absorption, blood modifications as adaptation to disease and to height, pygmy early puberty...

There are far too many people who "go against the grain" whenever the societal opportunities present themselves to be relegated to mere "exceptions."

Everyone is exceptional if you find what they're exceptional at. But even the exceptional are conventional most of the time.

A few? Try most of the women who do take up martial arts for a lengthy period of time.

Exactly. What about a woman with zero training facing a dude with zero training? Training can turn anyone into a competent fighter. Especially because everyone could potentially have some advantage in fighting against another, even if their advantages are going to be different.

Because women have been heavily socially conditioned for millennia for reasons I mentioned before to perceive that it's "unladylike" to fight or defend themselves, or play the role of warrior, and that they are supposed to rely on men to protect them, and even to find men with fighting skills attractive.

You're describing hypergamy. And then wrongly attributing it to societal pressures.

No. Hypergamy expresses a preference for the healthy. That preference is genetic and happens in all species with a hard sex determination system. Women prefer muscular males because a higher muscular mass (as opposed to thinner and to fatter males) projects more health. (Today we know this isn't necessarily true, but as a proxy available before blood and urine tests could be run, it is not a bad one). More muscular males look more a warrior type, but in reality they may be blacksmiths who got muscular through their professions without ever fighting anyone.

However, see how well men do against women in sports like volley ball or basketball, where speed, stamina, and reflexes are more important than sheer physical resilience.

Um?

https://goodmenproject.com/sports/why-men-hate-womens-basketball/

http://bleacherreport.com/articles/376048-could-the-uconn-women-beat-a-mens-team

. I won't ask why that is difficult for you to understand, because you insist upon genetic determinism as the rule.

If gender roles were really so flexible and indeterminate, then they wouldn't exist as they do. Instead of nearly every society on earth having them in one way or another (despite individual exceptions such as Thai ladyboys, Afghan bacha bazi, and Gertrud Scholtz Klink) and an active rejection being rare (or, dare I say, exceptional?), we would see the reverse: that nearly no society has them and their active creation is the rare, exceptional thing.

The human palette is immense; but not infinite. And there are some very strong tendencies. The organization of social and familial roles along gender lines is one of them.

Yes, the penis and vagina require different modes of waste extraction, etc.

Well I was talking once with an M2F trans, and she (yes, she) said she had always peed sitting down like a lady.

And freedom of choice means being freedom from pre-set expectations.

No. It means your choice is not coerced before or during taking it; and is respected after taking it. It doesn't mean that some choices aren't expected over others. If I expect some guy isn't going to kill me, that isn't taking away their freedom of choice.

Indeed, and guess who the biggest trend-setters have always been?

Euh?

I'm surprised you of all people don't know it. Unless it's a rhetorical question.

It is AG's. It's even been proven by research.

which is why so many of them have become SJWs themselves.

Erm, no.

That is White Knighting, and it is a behavior also based on evolution. The theory being that women will fall back on White Knights when they are agressed upon by the more macho set of males.

As a general tendency, maybe it works. As an individual strategy, it doesn't, but survives enough times to be passed on.