(Sorry in advance for spamming buzzwords)
Soo, If I'm not mistaking... *Googles therians* I'm likely not mistaking. Then Therians are people who believe their psychologies are / are strongly resillient of, that of an animals, And you're asking why they exist?
Why do people, A.K.A, "Bald monkies", often share soo many psychological traits with animals?
This question is a little more complicated than many people seem to think, because for you to carry an/ traits of, an animal soul or spirit there will have to be information passing on from one living creature to another, and for that information to arrive at it's recipient it has to be percievable.
The possibilities of wich are:
-To make this transfer of information possible, Either or one of your ancestors has had physical contact with said animal in a way that's undoubtedly gonna get me banned from this forum by describing it. I strongly doubt that any of you will be wiling to accept that explaination...
-The information is transferred in a way wich is non-percievable in our universe.
Wich is just such an extremely far stretch involving physics in extra-dimensional signal propogation, non-controlled selective-calling and a bunch of quantum mechanics that I know absolutely nothing about.
It's just such a far stretch that it's likely not even worth looking into with our current day understanding of physics.
-The transfer happened in a timeframe before the human race had any effective ways of detecting signals off the visible spectrum, and stopped before humans gained the technology.
To wich I ask the simple but loaded question: "Why the absolute [Redacted]!?"
-Or the simplest and most direct explanaition from the bunch: The Human race has grown to the size and diffusity similair to that of our ecological biome.
And thus, due to it's size and the wide variety in ways that a human can make a living in it, we have all treaded in diffirent paths of evolution, picking up survival tactics similair to that of diffirent animals, that after skipping a very long and complicated explanaition has resulted in us having specialised in certain ways of surviving, Varieties in psychology and behiour, diffirent moral standards and values, and even diffirent processen in "finding a mate".
It's just the simpelest and most likely explanaition to why humans share soo much with certain animals.
And as much as it sucks, and as boring as it is, The simpelest explanaition is usually true...
Just, please understand that I'm not excluding any possibilies or explanation and have undoubtedly missed a few. I'm just tinkering about this as well.
[EDIT]: Oh, boy, I'm rather late to the party, aren't I?