The 300M number Dr. Jordan Peterson(1) cites is a one possibility and the hierarchy going back only 13M years(2) is another. Orangutans and homo sapiens have a common ancestor about 15 million years ago, but orangs live without social hierarchy(3). This is probably why a small percentage of our species prefer to live as lone hermits: It's very possibly due to a recessive gene from not that long ago. It's also possible orangs had parallel evolution where they dropped hierarchies. The 300 million years ago when lobsters started having hierarchies could also have been their parallel evolution not inherited from the common ancestor we share with them.
We homo sapiens are equally or more hierarchical than chimps in their wild state. Our bipedal ape ancestors split off from them about six million years ago. Species change little if they don't have to; thus before our and chimps' common ancestor split, that ancestor was almost the same as today's chimps: Mega hierarchical and murderous (50% of male chimps die in chimp border patrol violence and chimps do genocide against other chimp troops; each troop having unique cultures in their troop sign languages etcetera; just as some human political cultures commit genocide).
- The main difference from us, chimps and bonobos (they split from chimps 2M ago) is our huge fore-brain versus their puny fore-brain. The three main *systems* of the mammal brain are hind, mid, and fore-brain; respectively instincts, emotions/subconscious, and intellect/future-forecasting. In each of us individual humans, as long as these three are on the same team, naming the hundred or so technical brain parts is Academic Ivory Tower Details (I capitalize religions) unless one is going for a medical degree.
- Our hind and mid-brains are almost clones of the bonobos' and chimps’. The hind and mid systems are the millions of years old and our fore-brains less than 200,000 years old -- in the prototype stage and like all complex prototypes, full of malfunctions that will take a long time to resolve. For instance we as a species can but don't sustain a reasonable quality of life for all.
Science has recently learned of our stomachs containing cells very
similar to brain cells. The reason is because hundreds of millions of
years ago, our anscestors didn't even have heads, let alone an organ
called "a brain"; but they did have gut feelings from their
stomachs. That was an extremely primitive version of thinking, but it
is a proven part; unlike our 200,000 year-old prototype fore-brain.
- As you can see from a brief history of our evolution, our bodies evolved as efficiently as possible to survive, and a part of this efficiency is when we humans are emotionally hurt, our brains use the same circuits as they do for physical pain. This is why emotions such as loss and heartbreak can be physically devastating as well.
Conclusions: 1. Evolution isn't as simple as "Such and such goes back 300M years" because there are complex patterns such as parallel evolution.
2. Hierarchies can be moral if their members can choose to leave a hierarchy for another or for no hierarchy.
(3) One offspring at a time lives with the mother, but paediatrics don't count as hierarchies. The male orangs sometimes rape the females, but these are one-night stands few and far in between and thus are not *social hierarchies* as they are with gorillas, chimps, and us.