Why is its possessive form without an apostrophe, when it’s opposite of other English rules and often counter-intuitive?

Question

See this headline: proper usage, but difficult to parse. “It’s” = “it is”, exclusively. The origin of this “exception” rule?

In: 6

Answer 1

I was hoping for some insight about when and how this became “codified”. Reciting back that the bird is assigned the name “wattled starling” still tells us nothing about the bird.

Perhaps we might ponder backwards to if spoken English ever had a time where “it is” wasn’t slurred into one contraction…