In English (and French) j is pronounced like a soft g. In Spanish j is pronounced like h. When and how did this divergence take place?
Additionally, when did 'i' and 'j' become separate letters? (I could google it, but this is more fun..)
In Latin, I and J were the same letter (I), with a consonant pronunciation sounding like soft g. How did this end up as sounding like h in Spanish?
This is not correct. In French, J (and also soft G, for that matter) is pronounced ZH, as the S in "pleasure" or the Z in "azure." The English soft G is two phonemes run together: D and ZH. Wrong again. Spanish J (and soft G) is pronounced like German and Scots hard CH, Russian X (usually transliterated as KH), Greek X (usually transliterated as CH) and CH in Czech, Polish and a few other Slavic languages that use the Roman alphabet instead of Cyrillic. The phonetic shifts in French have occurred sporadically over the centuries. For example, I've been told that the modern pronunciation of OI as "WA" only goes back about 200 years. The French language has a complicated and interesting history. The country that is now France was conquered by the Romans, and Latin was imposed as its language of government, commerce and scholarship. However, the people who lived there were not of Roman origin. The Franks, who lived in the northern part of the country, were a Germanic people. You can still hear the guttural Germanic R in the speech of Paris. But the Gauls, who lived in the southern region, were a Celtic people. You can still hear the flapped Celtic R in the speech of Nice. As these two populations were crammed together by the Roman bureaucracy, the evolution of a common language took some strange twists and turns. As if that weren't enough, Norsemen (or "Normans" as their name was twisted by French phonetics) invaded the northwestern part of the country in the 9th century, adding an overlay of Scandinavian vocabulary and phonetics. Old Norse (which has since fractured into Danish, Swedish and Norwegian) was a Germanic language, but a different branch of the Germanic family (northern branch: Norse; western branch: German/Dutch/English; eastern branch: extinct Gothic). In other words, French has been assaulted by external influences for centuries! As for Spanish pronunciation, my professors said that the odd phonemes you cite (Z and soft C as hard "th," intervocalic D as soft "th," J and sometimes X as "kh," and perhaps even the rolled RR) go back more than 500 years and may be Arabic artifacts of the Moorish invasion. Contrast Spanish with Portuguese, which didn't endure quite as much Arabic overlay, and today sounds a lot more like French than Spanish. Or compare it to Catalonian, which sounds more like Italian, even though most Spaniards can understand it after a couple of days' exposure.
