In a message dated 11/9/2007 9:17:20 PM Central Standard Time, 
[log in to unmask] writes:

>     At the time I thought it was inexplicable, but later I understood that 
> diphthongs like those, starting with "y" and "w" are heard by Greeks as 
> a gamma. The phoneme is similar, of course. More or less what happens 
> with B and V, or interdental sounds that are pronounced as /f/ or /v/ by 
> native speakers who lack the sound in their language (as when the French 
> say "sink" meaning "think", for example).
>     That's where you see how words like "iatros" (doctor) in Ancient Greek 
> became "giatros" in Modern Greek. Examples abound.

So to modern Greeks there is a sound there, audible as a gamma, that is 
simply a result of the Greek pronunciation, rather than any original sound or 
spelling.  Whoduh thunkit?