And spoken language, and writing, and masonry, and metalcasting, and cultivation, and domestication, scientific theory, logical thought, etc. A lot of things mattered a lot to get us where we are, and fundamentally changed the world when they happened (or at least changed the founders world in the short term as it spread globally).
Huge. Cats to eat the mice that would eat the
grain. Dogs to help in the hunting.
Goats for milk and meat. Sheep for
wool, milk, and meat. Horses for
power and meat. Cows for milk and meat.
Biggies.
Another biggie was open ocean sailing.
Why? Because there were no toll gates
on the open ocean! Across land
had to pay up to the local castle
each few miles. So, if got some
silk in the eastern Black Sea and
want to sell it in England,
go across Europe? Heck no: Just
get a ship and go by water.
Same for spices from India for
Europe, etc.
I would guess the wheel was part of the agricultural revolution? Maybe that's wrong.
edit: yes, it seems I was wrong, the wheel was discovered much after the agricultural revolution. http://en.wikipedia.org/wiki/Wheel#History Given that though, I wonder if its impact was smaller than the other great revolutions.