Rhythm

[IronWing]

What possessed our ancestors to spell it like this?

Edit:

 

[corwin]

What pocessed our ancestors to spell it like this?

You're asking about spelling

 

[Atomic Playboy]

They were maximizing Scrabble points.

 

[sixone]

You can thank both Romans and Greeks.

 

[Mr. Pedantic]

Why not?

In fact, the whole manifesto of the English language seems to be "why not?"

Why can't we have words bastardised from dozens of other languages? Why not?

Why can't we have arbitrary rules with more exceptions than adherences? Why not?

Why can't we make a language that pretends to be phonetic but isn't really? Why not?

 

[Fritzo]

It evolved from the Greek " rhuthmos", then the French rhythme. It wasn't originally spelled like that- they had to adapt letters to pronouce "ῥυθμός".