Tango*, Waltz*, and Polka* could be termed the “Foundational Dances” from which most other dances have evolved.
Tango (of today) is a dance of rhythms, where partners dance in a close embrace and share the experience of the rhythms they hear in the music. The incredible joy of tango comes from the mutual experience of the rhythms, shared through body contact, with no other agenda (no sex, romance, performing, impressing . . .).
The tango rhythm evolved (way over a century ago) from the Candombe rhythm brought to Argentina by African slaves. This same rhythm was also carried to other countries, including Cuba, where it evolved into Habanera (from “Havana”). Although it has disappeared in Cuba (where it had evolved into “Chachacha”), it has been preserved in the opera Carmen, by Georges Bizet. We still have access to this rhythm through the art of Bizet. See Habanera Rhythm** below.
A simplified representation of the Habanera rhythm, which conveys the timing but not the emphasis, but is readable by music amateurs (like me), is:
If the second note, a sixteenth, is combined with the first (a dotted eighth), then the rhythm becomes: slow, quick, quick, and it is often danced this way. Today’s tango dancing (to music from a century ago) is most often danced with this SQQ rhythm. In some tangos – mostly Milongas – it is heard and danced as SQQQ (with improvisational adjustments to shorten the S and the first Q to match the music – by feel).
Waltz spread world-wide starting in 1815; a century later it infected the newborn tango, and was called Vals Cruzada, and we now know it as Tango Vals. It has the distinct waltz beat of ¾ time, with 2 measures in a pair with primary emphasis on the first. In tango it is danced, using regular tango steps, as SQQ. The Slow is the combination of the 1,2,3 of the first measure. The first Quick is beat 4 (the first beat of the second measure). The final Quick may be beat 5 or beat 6, or it may fall between those 2 beats. The dancer may choose beat 5 or 6 or 5½ to create a different feel to the rhythm, to match the mood of the song or the mood of the dancer. This is just another improvisational variation in tango which is already improvisational in its nature.
Tango Vals music matches this rhythmic variation by emphasizing beat 5 or 6, but it is not hard for dancers to choose to hear it one way or the other. Reminiscent of waltz, tango Vals is often danced with many turns (especially by waltzers).
* Glossary: “Tango” here refers to the tango done today in the milongas of Buenos Aires; it’s not the tango of performances, movies, YouTube, or DWTS. “Waltz” here refers to the waltz done today in Vienna by Viennese people, who grew up with it. For more about Polka, see: http://www.waltzadventure.com/tango-discussions/the-greatest-dance-step-ever-invented/
** Habanera Rhythm (From Wikipedia)
Top: habanera rhythm—tresillo-over-two. Bottom: vertical hemiola—three-over-two.
The habanera rhythm’s time signature is 2/4. An accented upbeat in the middle of the bar lends power to the habanera rhythm, especially when it is as a bass ostinato in contradanzas such as “Tu madre es conga.” Syncopated cross-rhythms called the tresillo and the cinquillo, basic rhythmic cells in Afro-Latin and African music, began the Cuban dance’s differentiation from its European form. Their unequally-grouped accents fall irregularly in a one or two bar pattern: the rhythm superimposes duple and triple accents in cross-rhythm (3:2) or vertical