Papua New Guinea occupies the eastern half of the island of New Guinea, the second largest in the world, which it shares with Indonesia. It is home to 250 different mammals and 700 species of bird, and to the world’s largest butterfly, the Queen Alexandra’s Birdwing. 77% of the country is covered in tropical rainforest. Its territory is vastly unexplored; there are numerous groups of uncontacted peoples in Papua New Guinea, as well as countless species of plants and animals researchers believe are yet to be discovered.

Against that backdrop of biodiversity, an equally dazzling array of languages has blossomed in the Oceanian country. Papua New Guinea holds the record for most spoken languages, at an impressive 851, which include three official languages: English, Hiri Motu, and Tok Pisin.

In Indonesia, 719 languages are spoken and in Nigeria, 525. All together, the three countries speak 29% of the world’s 7111 languages. If they were to be spread out evenly across the world’s 195 countries, each would speak around 36 languages. Far more languages are found in tropical regions than anywhere else. Vanuatu, another Oceanian country, has 250,00 inhabitants spread across 80 small islands who speak 110 different languages. Russia, on the other hand, is about 1403 times larger, but is home to a “mere” 105 indigenous languages.

The factors that contribute to language diversity in different regions of the globe are varied. Researchers hypothesize that language patterns evolve according to history, cultural differences and geographic divides like mountains or rivers, but there is actually no clear answer to this article’s title question, nor any evidence pointing linguists in one single, definitive direction.

Something in the water

Michael Gavin is an Associate Professor of Human Dimensions of Natural Resources at Colorado State University. A few years ago, he attended a research workshop on the island of Makelua, in Vanuatu. He was the only participant who wasn’t originally from the island. All others came from 16 distinct communities who each spoke their own language.

The island was 100 kilometers long and only 20 kilometers wide, and in many cases, it’s possible to stand at the edge of a village and see the outskirts of the next closest village. And still, the inhabitants of each village spoke completely different languages, in a total of around 40 all across the island.

Inspired by that find, and by the question of why humans speak so many languages at all, Gavin and a team of linguists built a model to test to which degree basic natural processes like rainfall might help explain language diversity. They used Australia as the example.

The model assumed three basic things. First, that populations would move to available spaces where no one else lived yet; second, that rainfall would influence the number of people that can live in a place; and third, that each population would have an optimal maximum size, and whenever it grew beyond that, it would split into two groups that would eventually develop different languages.

An initial population would spring up on the map of Australia and grow in a random direction. Then, an underlying rainfall map determined the population density in different regions, in which the population divided into smaller groups whenever it reached the established maximum, filling up the entire country.

The model produced 407 languages this way, just one off from the actual number of aboriginal languages spoken in Australia — 406 — prior to any contact with Europeans. The real number was distributed across a map by Claire Bowern, a linguist at Yale University, who determined that more languages can be found along the coast as opposed to the dry Outback. Gavin’s simulated model showed the same language distribution.

It’s safe to assume that, in this particular case, rainfall played a crucial part in population and, consequently, language distribution. But it isn’t the only natural phenomenon that shapes the way human languages develop.

Ain’t no mountain high enough

Papua New Guinea is not only covered in tropical rainforests, but its terrain is mostly mountainous. Along with its coastal lowlands, swamps and many rivers, the country’s geography makes it difficult for populations to travel around. As a result, there are several groups who live in isolation, and have done so for so long, that they developed their own languages that are very different from each other.

A team of researchers at the University of New Mexico and Laboratoire Dynamique du Langage-CNRS in France, lead by Ian Maddieson, examined 628 languages from different parts of the globe and concluded that, in fact, the environment in which languages are spoken is key to their evolution.

The results of their study were based on the analysis of the amount of vowels and consonants used in each language and cross-referencing it against the climate and environmental conditions of the respective regions in which they’re spoken.

We find that the number of distinct consonants and the degree to which consonants cluster together in syllables correlate with mean annual precipitation, mean annual temperature, the degree of tree cover and the geographic elevation and ‘mountain-ness’ (‘rugosity’) of the area in which they are traditionally spoken.

Maddieson’s team’s finds allowed them to apply the acoustic adaptation hypothesis — different species adapt their acoustic signals to the environment they live in — to human languages.

In regions where vegetation is more dense, sound transmission is less uniform, with some sound waves being reflected by the vegetation, and others being diverted sideways. This affects specifically consonants, in particular the letters p, t and k, that have higher frequencies than vowels, which in turn explains why languages in regions with a greater tree coverage develop in different ways — favoring vowels — than in other parts of the world.

Other factors like air temperature, wind and precipitation have an equally important role in acoustic adaptation and, consequently, language evolution.

If we take another look at Papua New Guinea, not only did isolation contribute to its peoples’ language variety, but the natural environment of the regions in which they settled also played a crucial part.

Both Gavin’s and Maddieson’s research make a good claim for language diversity; it’s not hard to imagine so many languages being spoken in certain countries given the variety of existing natural sceneries and microclimates all over the world.

The origins of language

Yet in order to truly understand linguistic diversity, and eventually getting closer to explaining why humans speak so many different languages, we need to take into account not only the physical circumstances of a language’s users, but also their social and historical circumstances.

Linguists have long struggled to pinpoint a moment of language formation. David Armstrong, a now retired anthropologist who spent decades studying the origins of language, says the difficulty comes from the fact that language is a behavior, not a physical attribute, so there are no fossil records of its first appearance.

There are, however, two main hypothesis that explain the origin of languages and consequent diversity.

The first is the belief that all languages ever spoken by humans originated in one single language that spread across the world due to early humans’ nomadic nature. This idea is known as monogenesis. The second hypothesis is know as polygenesis and believes that, the same way humans evolved parallel in different parts of the world, so did language. Each of the original languages then split into numerous different ones.

Regardless of personal beliefs as to where languages originally come from, the fact is that languages have evolved not only due to environmental influences, but due to splits, extinctions and horizontal exchanges between humans as well, which we can observe throughout history.

Before settling into societies in fixed spaces, humans were nomads who travelled from one fruitful region to the next, whenever they ran out of resources. It was only after they started farming that humans began to settle in one place and eventually evolve into societies.

But humans kept moving, and migrations, in whatever form and point in time they might have taken place, helped spread languages with different origins all over the world. While different groups of people initiated contact with each other, they developed languages that were often a mix of the two already spoken ones. These would often start out as simplified versions of both dominant languages and evolve into proper languages by being transmitted to the next generations.

Languages have an organic quality to them that allows them to keep changing over time and with the people who use them. That’s why the word gay means something very different today than it did when Natalie Wood sang it, as Maria, in the 1961 West Side Story.

Humans currently speak 7111 languages. There may have been a time when there were even more languages being spoken around the world, before several tribes settled into bigger groups; and there may come a time when the number decreases, as languages die out because not enough people speak them.

Linguists still don’t agree on a concrete answer as to why so many languages came to be. What they do know for sure is that the number will constantly change as humanity, and the world, change as well.