Yeah, but they never say “this is greater than sliced bread”, it’s always “this is the greatest thing since sliced bread” which, to me, implies that sliced bread is still the standard-bearer.
So, sliced bread it is. Especially if somebody wrote on it. 
I would go with writing, myself. Think how much random knowledge was lost and rediscovered [or possibly never rediscovered] without recordkeeping. Growing is fine, but if the wrong person dies without training a replacement, knowledge is lost and possibly never rediscovered.
I have heard it argued convincingly that the greatest invention ever was the plow. It allowed us to have surplus food, which allowed armies, priests, scientists, builders, just about everything.
But I am torn between that and the blowjob.
Another vote for boxer briefs. No longer must we make the Sophie’s choice between support and not looking dorky. It is an underwear with no downsides.
When the choice is between the plow (noun) and the blowjob (verb), my appreciation of the plow is very abstract.
Amen. Preach it brother!
In roughly chronological order:
[ul]
[li]fire[/li][li]stone tools[/li][li]agriculture[/li][li]writing[/li][li]printing press[/li][li]iron/steel blast furnace[/li][li]steam engine[/li][li]electric generator/motor[/li][li]internal combustion engine[/li][li]vacuum tube[/li][li]nuclear power[/li][li]vaccines and antibiotics[/li][li]general-purpose digital computer[/li][li]laser/maser[/li][li]silicon chip[/li][li]DNA sequencing[/li][/ul]And some possible future entries:
[ul]
[li]self-replicating fabricator[/li][li]buckyfiber[/li][li]general-purpose quantum computer[/li][/ul]
I don’t think language counts as an invention any more than upright posture would.
The greatest invention is agriculture, if we measure “greatest” by having the biggest impact on the human species. Second greatest: writing.
But oral sex is definitely a close third! 
Actually, the electric telegraph allowed instantaneous communication before the telephone. The telephone was just an incremental improvement.
In fact, you could that the electric telegraph was just an incremental improvement over semaphore lines (Optical telegraph - Wikipedia), which were an improvement over things like torches and smoke signals.
Really, nobody else said wheel? Isn’t that the standard answer for every “best invention” question ever? :dubious:
At this board, we’re all Incan’s at heart and think the wheel is only suitable for toys.
How about just listing Sid Meier’s Civilization game technological research tree?
Corrected order:
[ul]
[li]stone tools[/li][li]fire[/li][li]agriculture[/li][li]writing[/li][li]iron/steel/blast furnace[/li][li]printing press[/li][li]steam engine[/li][li]electric generator/motor[/li][li]internal combustion engine[/li][li]vacuum tube[/li][li]vaccines and antibiotics[/li][li]nuclear power[/li][li]general-purpose digital computer[/li][li]laser/maser[/li][li]silicon chip[/li][li]DNA sequencing[/li][/ul]
Shouldn’t transistors (or, more generally, semiconductors) be in that list somewhere?
I “split” them between vacuum tubes* and silicon chips.
*“vacuum tubes” being shorthand for several technologies based on passing electricity through an evacuated glass container, including incandescent light bulbs, x-ray machines, cathode ray displays and triode amplifiers.
Writing was great, no doubt, but everything that can be done via writing can also be done via spoken language. Writing makes the sharing and preservation of information much more robust, but spoken language is what makes it possible. The only quibble would be whether spoken language actually counts as an “invention”, which I’ll admit is debatable.
And in one of Heinlein’s books, one character argues that the most fundamental human invention is politics. Though the character who made that argument was a politician, so take that with a very large grain of salt.
Refrigeration has to be near the top of any list. The preservation of foods and the cooling of living/working space has allowed for greater comfort, and mass food production/distribution and storage.
Precursors are not inventions, they are experiments. I maintain it was the phone that changed things, by being accessible, logical, and reliable.
How about money? Or, more specifically, a standard means of exchange, be it gold, salt, tobacco leaves, etc… It allowed for specialization of labor so a tailor, for instance, could sell a suit for a certain exchange rate and convert it to food, tools, shelter, fuel for heating and cooking while the farmer could do the same with his produce. No longer did each individual have to hunt, farm and build their own shelter. Much more accurate and equitable than the barter system.
(They could also buy that third thing on some people’s list)
Money! Interesting thought.