Languages and Genes Have Not Always Evolved in Parallel
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More than 7,000 languages are spoken around the world and passed down from one generation to the next - much like biological traits. But did language and genes evolve in parallel over the millennia, as Charles Darwin originally suspected?
For the first time, an interdisciplinary team from the University of Zurich, together with the Max Planck Institute for Evolutionary Anthropology in Leipzig, has investigated this on a global scale. Dubbed GeLaTo (Genes and Languages Together), the researchers compiled a database of genetic and linguistic information on 4,000 individuals speaking 295 languages and representing 397 genetic populations.
Every fifth gene-language relationship points to a language switch
In their study, they examine the extent to which the linguistic and genetic histories of these populations match. People who speak related languages are often also genetically related, but not always. "We focused on those cases in which the two patterns differ and examined how often and where this occurs," says study leader and UZH geneticist Chiara Barbieri, who conducted the study as a postdoc at the Max Planck Institute together with other researchers.
The conclusion: About every fifth gene-language relationship worldwide is a language switch. This gives clues to human history. "As soon as we know where which language shifts took place, we can reconstruct the history of how languages and populations spread around the world much better than before," says Balthasar Bickel, Director of the National Center of Competence in Research (NCCR) Evolving Language and one of the senior authors the study.
Switch to the local language
In most cases, populations switch to the language of neighboring populations that are genetically different. For example, some peoples on the tropical eastern slope of the Andes speak a Quechua idiom that is typically spoken by people with the high-altitude gene profile. Related to the Bantu, the Damara of Namibia communicate in the local Khoe language. In the rainforests of central Africa, hunter-gatherers use dominant Bantu languages without being genetically descended from these neighboring populations.
There are also typical cases of migrants who tend to adopt a local language: for example, the Jewish population in Georgia expresses itself in a South Caucasian language, that of Cochin in India in a Dravidian. Malta reflects the history of the island between the continents: the population is very similar to the Sicilian, but speaks an Afro-Asian language with influences from various Turkish and Indo-European languages.
Maintain your own linguistic identity
"Apparently it's not difficult to give up your language, also for practical reasons," says senior author Kentaro Shimizu from the University Research Center (URPP) "Evolution in action: from the genome to the ecosystem". On the other hand, it is rare for people to retain their original idiom despite genetic assimilation. “Hungarians, for example, have genetically adapted to their immediate environment. However, their language remains related to the languages of Siberia."
In this way, Hungarian speakers maintain a cultural difference in the midst of the Indo-European language family, which is most widespread in Europe and parts of Asia and includes French, German, Hindi, Farsi, Greek and many others. Indo-European has not only been well researched scientifically, but also has a particularly high genetic and linguistic congruence. "Until now, this has given the impression that similarities between genes and languages are the norm - but this is not reflected in our data," concludes Chiara Barbieri. She argues that in the future global data should also be taken into account.
Reference: Barbieri C, Blasi DE, Arango-Isaza E, et al. A global analysis of matches and mismatches between human genetic and linguistic histories. PNAS. 2022;119(47):e2122084119. doi: 10.1073/pnas.2122084119.
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