Short answer: It’s complicated.

Medium answer: As above, but in Western culture, this dynamic was reinforced by the advent of private property, which created a need to protect assets. While forms of patriarchy exist without private property, the patriarchy we recognize today is theorized to have been shaped by a perceived “need” for a dominant figure to hold and maintain property. Many factors have contributed to this dominance, but the factors of stoicism and emotional repression you describe are a significant facet tied to enforcing the male role as protector of property.

Long answer: As above, and as Simone de Beauvoir explains in The Second Sex, which is ~1000 pages, these roles evolved into patriarchal systems that have shaped society for centuries. Feminism as a whole is dedicated to unraveling these complexities, and the points above are only a broad overview of a much larger, nuanced topic.

Layman’s answer for those without time to read massive works of analysis: If you haven’t, I highly recommend reading bell hooks’ The Will to Change. It’s available as a free PDF on the Internet Archive. The book is under 200 pages and written to be accessible to non-academics, so feel free to skim and jump between chapters as suits your curiosity. The introduction and chapter 2 may be especially helpful for understanding this topic! 😁

Theres restraint and then there's also suppression. You can find encouragements to restrain oneselves going back to proverbs in the bible or the ideals in Roman society.

Although controlling yourself was seen as advantageous in general, men were not expected to supress their emotions, quite the opposite. It was fine to be angry or vengeful or lustful or in love etc just as long as it was directed at someone lower in the social hierarchy.

Christianity probably had a hand in supressing those outlets, though looking at history is doubtful that the majority of the population were 'pious' like that.

Where it seems to have taken a notable turn is during the Victorian era. The social expectations of 'proper' behaviour started to constrain the outlets men were 'allowed' to have. Not just on the battlefield, where controlled marching into musket fire was more important than ever, being stoic in everyday life was becoming an ideal to restrain vice. Prostitution was becoming more taboo, as was gambling, and violence in general.. at least in "civilised" society. Which in turn was possibly driven by the industrial revolution moving everyone to cities where living close together made these "sin"s more visibly awful.

Warfare had always been awful, but there was honour in man to man struggle. What got far worse from the 1700s on was needing an army to not crumble in the face of impersonal volleys of musket fire and canister shot from batteries of canon half a mile away. The era of feats of strength was over. Now you could get horribly mangled at random for standing in the wrong place. This was the origin of the British "stiff upper lip", the ability to meet misfortune with indifference. The beginning of widespread supression of emotions.

From the Victoria era, add in half a century of industrialised warfare, the grimness of which had never been seen before. And by the 50s/60s society was dealing with very broken men who had been traumatised and given no better advice than "be a man and suck it up". Which has disastrous consequences, not just for men but also domestic violence and abuse or neglect where things tipped over.

The hippie movement rediscovered men's 'softness' but wasn't practical. The eighties was practical - created an outlet in the deregulated business world of working ruthlessly and making personal riches - but it lacked "wellbeing".

It's really only in the millennial and gen z generations that this historical trauma is distant enough and society's ideals have changed enough that we can even begin to have public conversations about men going to therapy or crying on a friend. This would have been sappy even in the 90s.

Are stupid non researched hypothesis allowed? I had in my mind: maybe those roles come from times when life was more violent, so having a strength advantage due to biology was an obvious way to hold power and impose rules that benefit your group/gender. I feel this somehow connects to emotional behaviors that may be required for war and politics, such as not showing your weaknesses. Then you have centuries of cultural development, such as religions, that created layers of justification for the social order that benefited the people in power, even when the physical strength advantage is not relevant anymore, and that’s what we consider tradition.
Reality is probably more complicated.
Is patriarchy and the emotional difference really specific to Western society, if we compare to Arabic, Indian or Chinese traditional cultures, for example?

What you describe sounds like me but not most men I know. Im not an outwardly emotional man but most to me are sorta gregarious.

Man, you need a full on historian for this, but I'll try.

Iirc, the whole stoicism thing started in Ancient Greece, but there's probably earlier instances of it. It waned and waxed throughout the centuries, growing stronger sometimes and growing weaker others. The current way of it is basically from the protestant way of thinking combined with various wars, like WW1. I seriously hope you go reading stuff outside of Lemmy, I haven't studied this stuff in over a decade.

Now, for a non-western perspective, the east has a similar concept in Bhuddism, and it's just as old as western stoicism.

Iirc, there was also some Indian tribe (Cherokee?) that also made a big deal of it. I can't speak much on it.

For the record, stoicism is not about being a robot, it's about being emotional stable. There's a massive difference.