> "go to battle"

I remember that in the first days after my kid was born, the thought that I would defend that child to the bitter end against any attacker suddenly seemed completely natural, even trivial. It was quite strange and included a sudden extreme awareness of (and aggressive feelings against) animals which came to close. This included dogs. The feelings were overwhelmingly archaic. I talked to my wife about this, she experienced the same. I now understand the aggressiveness of animals who protect their offspring. I felt it myself.

There seems to be some research regarding this: https://journals.sagepub.com/doi/pdf/10.1177/147470491666228...