That would be English, of course:
There is a huge shift underway, and it has become extremely rare to meet a scientific researcher or international business-person who cannot speak fluent English. How else would Peruvians communicate with the Chinese?
But wait a minute. Peruvians speak Spanish, the world’s second-biggest language, and Chinese has the largest number of native speakers of any language. Why don’t they just learn each other’s languages?
Because neither language is much use for talking to anybody else. Chinese won’t get you very far in Europe, Africa or the America — or, indeed, in most of Asia. The same goes for Spanish almost anywhere outside Latin America. Since few people have the time to learn more than one or two foreign languages, we need a single lingua franca that everybody can use with everybody else.
The choice has fallen on English not because it is more beautiful or more expressive, but just because it is already more widespread than any of the other potential candidates.
Mandarin Chinese has been the biggest language by number of speakers for at least the last thousand years, and is now used by close to a billion people, but it has never spread beyond China in any significant way. Spanish, like English, has grown explosively in the past two centuries: Each now has over 400 million speakers. But Spanish remains essentially confined to Central and South America and Spain, while English is everywhere.
There is a major power that uses English in every continent except South America: The US in North America, the United Kingdom in Europe, South Africa in Africa, India in Asia, and of course Australia (where the entire continent speaks it). All of that is due to the British empire, which once ruled one-quarter of the world’s people. For the same reason, there are several dozen other countries where English is an official language.
Of course, the British empire went into a steep decline almost a century ago, but the superpower that took Britain’s place was the United States, another English-speaking country.
After another century during which everybody dealing in international business and diplomacy — indeed, any independent traveller who went very far from home — simply had to learn English, the die was cast. English had become the first worldwide lingua franca.
There have been few languages in world history that were spoken by more people as a second language than as a first; English has had that distinction for several decades already. Never before has any language had more people learning it in a given year than it has native speakers; English has probably now broken that record as well.
I think this is wonderful. English is by far the richest language in human history, this because it happily absorbs useful concepts from every language it bumps into. My advice for non-native students of English: Learn Latin, too, at least Latin vocabulary. The atomic forms English adopted from Latin in six separate invasions of English by Latin will make understanding English vocabulary much easier, as well as giving you the linguistic basis for coining ever-newer English neologisms.
