The Indo-European Question: Mapping the Origins and Expansion of the Indo-European Language Family
To the untrained ear, languages like English, Dutch, Spanish, Russian, Greek and Hindi might all sound very different from one another but in fact they show remarkable similarities. Where the English use mother, for example, we find moeder in Dutch, madre in Spanish, mat’ in Russian, mitéra in Greek and Māṁ in Hindi.
On the basis of many systematic similarities like this, scholars have concluded that these languages, and hundreds of others from across Europe and the Near East, are in fact all related, having “sprung from some common source, which, perhaps, no longer exists”.
Dubbed the Indo-European language family, this group of linguistic relatives stretches from Icelandic in the west to Singhalese, spoken in Sri Lanka, in the east. However, despite over 200 years of careful scholarship, the origins of the family remain controversial.
In a commentary in Science on the expansion of the world’s languages, Jared Diamond and Peter Bellwood call the origin of Indo-European “the most well-studied and yet still most recalcitrant problem in historical linguistics”.
Two competing theories
There are two main competing hypotheses for the homeland of the Indo-European languages. Each theory implies a different location and time depth for the Indo-European language family – on the Pontic steppes 5000-6000 years ago or in Anatolia 8000-9500 years ago.
The conventional view, first put forward by Marija Gimbutas, links Proto-Indo-European (the hypothesized ancestral Indo-European tongue) with archaeological evidence for the expansion of a semi-nomadic, pastoralist people, known as the Kurgans, from their homeland in the Pontic steppes out across Europe and the Near East during the fifth and sixth millennia BP.
The second theory, proposed by archaeologist Lord Professor Colin Renfrew, holds that the language family spread with the expansion of agriculture from Anatolia between 8000 and 9500 years ago. A spread of languages with agriculture has also been argued in the Pacific, Southeast Asia, and sub-Saharan Africa.
A group set out to test between these hypotheses by modelling the evolution of the language family through space and time and asking whether one scenario was significantly more likely than the other. They used Bayesian phylogeographic approaches, together with basic vocabulary data from 103 ancient and contemporary Indo-European languages, to explicitly model the expansion of the family and test these hypotheses.
They found decisive support for an Anatolian origin over a steppe origin. Both the inferred timing and root location of the Indo-European language trees fit with an agricultural expansion from Anatolia beginning 8000 to 9500 years ago. These results highlight the critical role that phylogeographic inference can play in resolving debates about human prehistory.
Language expansion in time and space
Figure showing the expansion of the language family across Europe through time:
Estimates for the location of ancestral nodes on the tree (representing ancestral languages) are plotted as opaque points with a color that indicates their corresponding age. Older nodes are shown on the foreground to better show the expansion.
(NB: – This figure needs to be interpreted with the caveat that we can only represent the geographic extent corresponding to language divergence events, and only between those languages that are in our sample. The rapid expansion of a single language and nodes associated with branches not represented in our sample will not be reflected in this figure. For example, the lack of Continental Celtic variants in our sample means we miss the Celtic incursion into Iberia and instead infer a later arrival into the Iberian peninsular associated with the break-up of the Romance languages (and not the initial rapid expansion of Latin). The timing represented here therefore offers a minimum age for expansion into a given area.)
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