With more than 2,000 distinct languages, Africa has a third of the world's languages with less than a seventh of the world's population. By comparison, Europe, which has about an eighth of the world's population, has only about 300 languages.

Africa's linguistic diversity can even be found among individual Africans. For instance, a study of 100 inhabitants in a city in western Uganda found that the average speaker knows 4.34 actual languages.

So why is this anyway? To help explain diversity, linguists borrow tools from evolutionary biologists: linguists explore the relationships between distinct languages in the same way evolutionary biologists explore family relationships and speciation of living things. Given the parallels in these two fields, it's no coincidence that Africa, the place of highest genetic diversity, contains rich linguistic diversity as well.

The origins of high genetic diversity

"Pretty much every study that's ever been done involving looking at genetic variation in Africans compared to non-Africans always shows more diversity in Africans," University of Pennsylvania geneticist Sarah Tishkoff tells the Monitor.

Population genetics theory predicts that the highest level of diversity exists at the source of the population's origin. For humans, that is Africa.

"Modern humans have been in Africa longer than any other region of the world," says Tishkoff. "And secondly, that there was a bottleneck…or founding event when some small numbers of people left Africa, giving rise to the rest of the world. They lost diversity during that migration event."

Humanity's African origins has not only led to high genetic diversity on the continent, but it has also helped spur other kinds of variation as well.

"There's just been a lot of time for cultural diversity, linguistic diversity, genetic diversity to accumulate in Africa," Tishkoff says.

There could also be environmental and political explanations, according to University of Chicago evolutionary linguist Salikoko Mufwene.

"One is that in the case of Europe, you have to factor in the emergence of various empires, and these various empires were assimilationist and they may have driven a number of languages already to extinction," says Mufwene.

Different choices by political leaders of the past may have then allowed for small languages to survive in Africa while similarly-sized languages died elsewhere.

"Traditional African kingdoms were not as assimilationist as the European empires…say the kings relied on interpreters to translate to them what was coming from territories that they ruled but where people spoke different languages, there is no particular reason why we should be surprised that there are so many languages spoken in Africa."

Is Africa the most linguistically diverse place on Earth?

Should Africa be considered the most linguistically diverse continent? It depends on how you define diversity.

Ethnologue, a project to catalogue the world's languages conducted by the religious organization SIL International, created an index of linguistic diversity based on a scale from 0 to 1.

Papua New Guinea wins out as the country with the highest index of linguistic diversity at 0.988. When one looks at the top ten countries, three are part of Oceania but the other seven are on the African continent. Of the 25 most linguistically diverse countries, according to this indexing method, 20 are African, and just below these are others like Ghana and Zambia.

While the numbers are compelling, the data doesn't automatically provide the continent with the title of most language diversity.

"If [linguists] define linguistic diversity in another way, maybe they see something different," says Tishkoff.

Researchers don't have to look only at the number of speakers or the size of the geographical area. They can also look at how different languages are related to one another and how they are structured to determine overall linguistic diversity.

In a separate index of diversity sponsored by non-profit Terralingua, investigators Jonathan Loh and David Harmon defined linguistic diversity as the number of languages and the evenness of distribution of mother-tongue speakers among languages in a given geographical area. In this context, it not only matters that a large number of languages are present, but also that one language doesn't overwhelm the others.

Mr. Loh says they did not find a strong correlation between the human genetic diversity on the African continent and its linguistic diversity.

"There's huge linguistic diversity in Africa, but it's not concentrated in Africa in the same way as genetic diversity," says Loh.

As Ethnologue data shows, places in Oceania such as Australia and New Guinea contain large numbers of languages over relatively smaller land areas. And there's another reason other continents are able to compete with Africa's high number of languages: less constraint.

"Languages evolve so much faster," says Loh. "Cultural evolution is so much faster than biological evolution."

How is Africa preserving its linguistic diversity?

With nearly a quarter of the globe's languages considered threatened, it wouldn't be unreasonable to assume the continent with 2,000 living languages is also the region with the highest language loss. But the research points elsewhere.

Loh and Harmon also studied loss of linguistic diversity over time. And while the African continent makes up a large proportion of the world's languages, only about 13 percent of African languages are considered threatened. Meanwhile, in the Pacific region, which includes other areas of high linguistic diversity such as Australia and New Guinea, more than 60 percent of indigenous languages are threatened.

"The Americas and Australia are areas of the world which have been culturally dominated by European languages since colonization…" says Loh. "Sure there were European colonies in Africa, but there wasn't the migration of population from Europe to Africa in the same way as there was from Europe to the Americas or Europe to Australia."

Though Africa may not have been permeated by European languages to the same extent as other regions, allowing for lower levels of diversity loss today, African countries could still go the way of building up one or two dominant languages.

"If African economies develop on the European model, which means that there will be greater urbanization and greater population mobility and, therefore, greater competition among the languages, there's a chance that Africa under those conditions would take the same evolutionary path as Europe, with very small number of languages compared to the large size of the population," Mufwene says. "But if Africa doesn't develop in that direction, there's also a greater chance that even the smallest languages may still survive."

Why understanding linguistic diversity matters

So Africa has great linguistic diversity and a good number of those languages aren't going anywhere just yet. But why is it necessary for researchers to know how diverse Africa or the other continents are linguistically?

To conservationists, the reasons for measuring diversity can be the same as the justifications for conservation itself: the ethical stance that populations have the right to hold on to their languages and the utilitarian stance that language variation provides us with different sets of knowledge.

"We need to understand it, measure it, map it and so on before we can try to conserve it," Loh says.

There also exist motivations within political science and history for measuring the level of linguistic diversity for a place.

"Countries both developing and industrialized, whether it's France or China or Ethiopia, they've all had these kinds of policies to enforce a unified language and then by extension unified culture. Of course that comes at an enormous cost, but not necessarily one that can be measured in economic terms…" says Loh. "So there are political drivers of extinction and being able to express and scribe cultural diversity around the world might help to try to redress that."

"It can tell you something about the history of the people and the region," Tishkoff says. "It could indicate high levels of migration to a region of people speaking different languages."

Mufwene agrees that knowing about a region's linguistic or cultural diversity says something about the people themselves. Though the level of language diversity in a country or region is, to a certain extent, under the control of political leaders or left to environmental circumstance, the preferences of the people matter.

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"If people prefer to have one language spoken by millions and millions of people, it makes life easier," says Mufwene. "But if people are more interested in having different identities and language functions as a marker of identity, then it's also very convenient to speak more languages because it's easier to tell which person is from where."

This is the second installment of a series on global language evolution. The first installment looks at the possible drivers of language extinction and consequences of less language diversity.