It's widely thought that human language evolved in universally similar ways, following trajectories common across place and culture, and possibly reflecting common linguistic structures in our brains. But a massive, millennium-spanning analysis of humanity's major language families suggests otherwise.
Instead, language seems to have evolved along varied, complicated paths, guided less by neurological settings than cultural circumstance. If our minds do shape the evolution of language, it's likely at levels deeper and more nuanced than many researchers anticipated.
"It's terribly important to understand human cognition, and how the human mind is put together," said Michael Dunn, an evolutionary linguist at Germany's Max Planck Institute and co-author of the new study, published April 14 in Nature. The findings "do not support simple ideas of the mind as a computer, with a language processor plugged in. They support much-more complex ideas of how language arises."
How languages have emerged and changed through human history is a subject of ongoing fascination. Language is, after all, the greatest of all social tools: It's what lets people share and cooperate, divide labor, make plans, preserve knowledge, tell stories. In short, it lets humans be sophisticated social creatures.
One school of thought, pioneered by linguist Noam Chomsky, holds that language is a product of dedicated mechanisms in the human brain. These can be imagined as a series of switches, each corresponding to particular forms of grammar and syntax and structure.
The findings 'do not support simple ideas of the mind as a computer, with a language processor plugged in.'Such a system would account for why, of the nearly infinite number of languages that are possible -- imagine, for instance, a language in which verb conjugation changes randomly; it is possible -- relatively few actually exist. Our brains have adapted to contain a limited, universal set of switches.
A limited set of linguistic universals is exactly what was described by the late, great comparative linguist Joseph Greenberg, who empirically tabulated features common to language. He made no claims as to neurological origin, but the essential claim overlapped with Chomsky's: Language has universals.
If you speak a subject-verb-object language, one in which "I kick the ball," then you likely use prepositions -- "over the fence." If you speak a subject-object-verb language, one in which "I the ball kicked," then you almost certainly use postpositions -- "the fence over." And so on.
"What both these views predict is that languages should evolve according to the same set of rules," said Dunn. "No matter what the language, no matter what the family, if there are two features of language that are somehow linked together structurally, they should be linked together the same way in all languages."
That's what Dunn, along with University of Auckland (New Zealand) computational linguist Russell Gray, set out to test.
Unlike earlier linguists, however, Dunn and Gray had access to powerful computational tools that, when set to work on sets of data, calculate the most likely relationships between the data. Such tools are well known in evolutionary biology, where they're used to create trees of descent from genetic readings, but they can be applied to most anything that changes over time, including language.
In the new study, Dunn and Gray's team created evolutionary trees for eight word-order features in humanity's best-described language groups -- Austronesian, Indo-European, Bantu and Uto-Aztecan. Together they contain more than one-third of humanity's 7,000 languages, and span thousands of years. If there are universal trends, say Dunn and Gray, they should be visible, with each language family evolving along similar lines.
That's not what they found.