Anarchism

Hierarchy in the Forest by Cristopher Boehm is literally about this. In short, we've always had some kind of "hierarchy", but starting at about 3 million years ago, and becoming ubiquitous at around 300,000 years ago, we "inverted" the hierarchy so that domineering individuals were ostracized, and everybody else was more or less equal. In other words, we found a way to be egalitarian, despite our despotic roots as a species - and we did it for long enough to significantly impact the human genome.

Then the domineering individuals started to figure out how to undo this and form dominance hierarchies again, starting about 40,000 years ago.

Well it really depends on what you call a hierarchy.

If it's a social organization where one person can take a decision that other peoples follow, then yeah, it probably emerged far before we evolved into humans. But it's not necessarily opposed to anarchism.

If you begin to add other elements of definition, like the fact that it happens in all aspects of life, that the organization is not agreed to by some or any of the people it applies to, that it is derived from spiritual, religious, economical or political principles instead of just emerging from people interactions, that it is tied with differences in ways of living, etc., then you get a quite stricter conception of hierarchy, and i think most people will agree that those emerged or crystallized with the switch from nomadic to sedentary societies and the rise of institutionalization of religion and politics.

So i'd say there's no clear moment because there's no clear definition of hierarchy, but i'd say there is a consensus to say that there has been a process of hierarchisation of societies at various steps of prehistory.

The Dawn of Everything goes into that subject pretty well.

What Is Politics also made a video series on that subject, which goes into where and when hierarchies began to form.

I'd wager social heirarchy is as old as homo sapiens if not older

The discovery of the Zachelmie trackways in 2010 suggests that stegocephalians possibly emerged 395 Ma or earlier.[5]

Tens of thousands of years old at least, lots of mummies and corpses have burial adornments and items that indicate they were the leader of the pack in the same way rulers later were and are buried with ceremonial offerings and adornments and written descriptions of them being a ruler.

As far back as we have any evidence for.

Aboriginal Australians might be interesting for you to look at as they had a much looser authority structure as nomads and have a societal history of 50,000 plus years old now(keeps getting updated as more sites are found).

So I read some of Marx's notes on the writings of social theorist Lewis Morgan. Obviously, a territory ruled over by a king is a hierarchical system. But the notes discuss how it may have become this way, that I found really interesting.

The works of Morgan was an analysis of the ancient Greek gens, gents, and gentiles. If you understand how Marx views history, I think he makes some interesting points, although these notes were not finished like Capital vol 1 (incidentally, when Marx died and Engels discovered he had been studying anthropology rather than writing subsequent volumes of Capital, he wanted to burn Marx's notes.)

So there are gens, which are like these egalitarian (non hebrew) religious groupings. And individual member of a gen, is a gentile. And the gens were like little religious communes, with egalitarian social sharing and authentic fraternity between members. But over time, despite the material egalitarianism, there develops differences in social standing, and accumulation of social capital. This informal hierarchy develops into formal castes (genres). And the fraternity, while still present in an abstract way, gives way to individual interests, or caste interests.

Over time, these distance castes begin to compete with each other. Eventually, one caste becomes socially and materially dominant over the others, establishing a hierarchy. As this develops, the fraternal and egalitarian nature of the society becomes more abstract, like an ideal that everyone gives lip service to, but which a ruling caste has actual material and social control over. Eventually, this develops into an aristocracy that has a formal ruling class and formal domination, and all the fraternity, symbolic and concrete, has disappeared, and is replaced with divine right to rule.

Now this is a study of a society from around 500BC, and aristocracy precedes that by a thousands of years. Basically, we can date the rise of monarchial social relations by the rise of the major religions, since religion is a necessary component, and caste within, monarchial relations. But the study of how those societies may have gotten there is seething I think about a lot. Granted, I'm no expert, this is a single source, and even then its just notes.

But I thought it was still a better answer than all the people who are guessing based on preconceived notions of how hierarchy "has always existed".

Some anarchists, feminists and anthropologist would say the first long term hierarchy was patriarchy. When men established positions of power (priest, warrior) that fit their interests well, they changed the societal structure from matricentric to patriarchal and started to establish the state.

Öcalan (not a scientist) dates this in his work Beyond State, Power, and Violence at around 6 thousand years ago for the area of the so calles Middle East.

Dont know how others see this but there probably is not a scientific or anarchist consensus on the topic.

Since before we were homo sapiens distinct from our evolutionary cousins. Probably before our ancestors were recognizable as mammals, or even terrestrial.