If someone could answer this question, I would really appreciate it.

My question is, in the following sentence, "One of the classic ways the limbic brain has assured our survivals as a species is by regulating our behaviour when confronting danger, whether it be a prehistoric man facing a Stone Age beast or a modern-day employee facing a stone-hearted boss." why "it be" is used here, instead of it is? And what's the difference between using it be and it is?

Thank you.
It's a somewhat archaic form, probably stemming from the subjunctive which used to be used far more than it is now.

Just consider it a fixed expression: he likes all vegetables, whether it be peas, carrots, or corn.
Students: We have free audio pronunciation exercises.
This is the present subjunctive for of the verb to be.

You can all you need and more here:

Emotion: big smile Thanks heaps! Philip
That website helps a lot. Thank you very much!
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