Well, that's a big part of the model.  But remember that practically 
every interesting molecule in our bodies has at least *two* uses.
Example: epinephrine is a neurotransmitter as well as a hormone. 
It's evident that at least *some* hormones are older than nervous systems 
themselves. And that they appear to serve as a backup system for 
signalling even in mammals is well known--vide the original discovery of 
histamine as the agent for stomach-acid secretion in cows with all 
the nerves to their stomachs cut (the histamine-stuffynose connection 
was discovered later, and the histamine-orgasm connection later 
still, I seem to recall).
Wild-assed-guess warning!
This suggests that epinephrine as a heart-speeder-upper may have been 
"pressed into" service as a neurotransmitter, or the two functions may 
have co-evolved. I don't know who would be able to determine that or 
how accurately; archaeo-molecular-biology is a tough science to 
practice.
So, do flatworms (or whatever critters have hormones) have 
rudimentary emotions? :)
<<
 Unfortunately, it seems that the
"emotional thinking" we share with other mammals continues on and can only
be overcome with conscious practice. [Anyone watch the Presidential
Debates?]
>>
Well, I have been settling for being able to *browse* my emotional 
state and getting practice at focusing my attention.
I'm afraid my attention is too precious a thing these days to waste 
on Tweedledum and Tweedledumber. :\ :P :
MMB, at but not for, etc.