I have just discovered Wikipedia’s page on a ‘List of common misconceptions’ that includes, among many other wonders, a great piece about the myth of the tongue taste map.
Different tastes can be detected on all parts of the tongue by taste buds, with slightly increased sensitivities in different locations depending on the person, contrary to the popular belief that specific tastes only correspond to specific mapped sites on the tongue.
The original tongue map was based on a mistranslation of a 1901 German thesis by Boring (an eminent psychologist at Harvard). In addition, there are not 4 but 5 primary tastes. In addition to bitter, sour, salty, and sweet, humans have taste receptors for umami, which is a savory or meaty taste.
You can see the referenced entry here and there’s much more joy on the complete page of misconceptions.
UPDATE: Thanks to commentors Steve and Vinnie for pointing me in the direction of the latest XKCD comic that mentions the ‘common misconceptions’ page. Not my source but a wonderful reference point!
Link to Wikipedia ‘List of common misconceptions’.
Mind Hacks 
I see somebody else reads XKCD too : )
Did you also learn about that Wikipedia page from the xkcd comic last night? It looks like the attention brought some visitors in the last day because I’m pretty sure there are a handful of entries that weren’t there last night. I think my favorite has to be the “fan death” one. New to me and utterly bizarre.
There is some evidence that there is a 6th primary taste, protein.
I found the “vikings didn’t have horns on their helmets” to be particularly disappointing…it’s a great page.
Thank you for referencing XKCD. That made my day. 🙂
Not just 5 primary tastes, butm 6 or even 7.
@Clay – I don’t know about your ‘protein’ taste, but in this article we explore the possibility of ‘fat’ and ‘calcium’
http://www.nature.com/nature/journal/v468/n7327_supp/full/468S18a.html
(In the interests of full disclosure, I was the associate editor for this supplement!)