Here's why:
* "Brute" itself can refer to a *person* (usually a man) who is physically strong and often aggressive. In this sense, it's more of an adjective than a noun.
* "Brute force" is a common phrase, but it's not a noun in itself, it describes a method of action.
* "Bestial" is an adjective that can be used to describe something animalistic or savage, but it doesn't have a specific noun form.
Depending on the context, you could use:
* "Physicality" or "Strength" to refer to raw power.
* "Aggression" or "Violence" to refer to the forceful nature.
* "Savagery" or "Primal instinct" to refer to uncivilized behavior.
Ultimately, the best word to use depends on the specific nuance you're trying to convey.