You can’t speak Spanish without the word y (“and”). It’s the fourth most frequent word in Spanish, after el/la, de, and que. It’s indispensable for telling time (Son las dos y veinte) and counting (treinta y cinco). It shows up in everyday expressions like blanco y negro, madre y padre, and ida y vuelta. And it has the magical property of both creating longer sentences (Comimos en la taquería y fuimos al cine) and shortening questions (¿Y tú?).

You probably already know that y changes to e before a word that begins with i or hi, as in Mi madre es bonita e inteligente or Tengo veinte sobrinos e hijos. This is more than a spelling change. The pronunciation changes, too, to prevent the adjacent /i/ sounds from blending together.

I knew this. And I also knew, from studying Latin for a year in college, that the Latin word for “and” is et. But somehow I never put two and two together (that’s dos y dos) to realize that Spanish e is a lot closer to the original Latin than the normal y form is.

In fact, as Tom Lathrop explains, y is another case of a historical “flip” in the language. Earlier this summer, this blog considered verbs like conocer and hacer, whose yo forms conozco and hago are irregular by modern standards but historically conservative. All the other present-tense forms of these verbs, plus the infinitives, have diverged substantially from Latin. Likewise, e can be traced back directly to Latin, while y is a Spanish innovation. So although from a modern perspective y is normal and e exceptional, from a historical perspective it’s the other way around.

Seen from a modern perspective, “y” is normal and “e” is exceptional. Seen from a historical perspective, it’s the other way around.

Let’s see how this happened. As Lathrop explains, Spanish lost the final t of et, as it did final -t in general; compare Latin dicit and Spanish dice (Lathrop p. 129). When the resulting e form came before a word that began with a vowel, it was natural to turn the sequence e + vowel into y + vowel. Lathrop gives these examples (p. 200). If you say the words out loud you should be able to recreate this transformation for yourself.

• e amigos > yamigos > y amigos
• e obispos > yobispos > y obispos
• e uno > yuno > y uno

This change happened before all vowels but /i/, for obvious reasons, and then took over before consonants as well. Poor e was now the odd man out.

The change of o “or” to u before o is a horse of a different color, by the way: a change that never quite got off the ground. O is the natural development of Latin aut. Penny explains that “The form u probably arose in pre-vocalic position [like y for e], and has only in the modern period come to be restricted to use before words beginning with /o/” (p. 199). It coulda been a contender!