>I wonder when mankind *did* first start making and using something 
the 
>size of a boat - the investment in time for even a dug out canoe, 
built 
>with fire or tools, must have been enormous.  And what would you do 
with a 
>hollow log anyway? 

I believe it was the Greeks. They even went so far as to build there 
own navy. They were sorta the Stanley Tools of their time
http://www.showgate.com/medea/ships/grkship1.gif

Regards
Jonathan