Genomic history of Canary Islands

A team of paleo-geneticists at Universidad de La Laguna on Cruz de Tenerife, working with colleagues from other Canary Islands and European institutes, has found that studying the genes of people living in the Canary Islands from the 3rd to the 16th century sheds light on the history of people living in North Africa around the same time.

In their study, reported in the journal Nature Communications, the group obtained bone samples from other research efforts and conducted genetic studies.

As archaeologists, historians and other researchers attempt to piece together the details of human history, going back as far as possible, they sometimes encounter blank spaces in the record. That has been the case with many parts of North Africa over the centuries from approximately the 200s to the 1500s. This is due, the researchers note, to the hot and dry climate.

The bones of those who lived there during that time have not been preserved well enough to extract DNA. To fill in some of the blanks, the team on this new effort looked instead at the bones of people living on the Canary Islands during that time. Prior research has shown that the people living in the Canary Islands during this period came from North Africa.

The work involved sequencing samples collected from bones and teeth unearthed on the islands during past digs by other research teams. They focused their attention only on bones and teeth of people known to have lived on at least one of the Canary Islands during the 3rd to 16th centuries.

The team found genetic ties between people living on the islands and those living in North Africa, mainly in what is now Morocco, dating back 5,000 years. They also found evidence of genetic influences from people living along the Mediterranean Sea, both in Africa and Europe—likely due, the researchers note, to migration across the Sahara.

The research team also found differences in the genes of people based on location—islands closer to Africa experienced more ancestral influence from European people, while those farther away were more African.

More information: Javier G. Serrano et al, The genomic history of the indigenous people of the Canary Islands, Nature Communications (2023). DOI: 10.1038/s41467-023-40198-w


The genomic history of the indigenous people of the Canary Islands


Abstract
The indigenous population of the Canary Islands, which colonized the archipelago around the 3rd century CE, provides both a window into the past of North Africa and a unique model to explore the effects of insularity. We generate genome-wide data from 40 individuals from the seven islands, dated between the 3rd–16rd centuries CE. Along with components already present in Moroccan Neolithic populations, the Canarian natives show signatures related to Bronze Age expansions in Eurasia and trans-Saharan migrations. The lack of gene flow between islands and constant or decreasing effective population sizes suggest that populations were isolated. While some island populations maintained relatively high genetic diversity, with the only detected bottleneck coinciding with the colonization time, other islands with fewer natural resources show the effects of insularity and isolation. Finally, consistent genetic differentiation between eastern and western islands points to a more complex colonization process than previously thought.

Introduction
North Africa has a unique geographical situation that has favored demic diffusion between continents. The Sinai Peninsula is a land bridge that supports migratory routes between the African continent and Eurasia. At the north, the Mediterranean Sea has been the center of the cultural and economic trade that shaped the history of the surrounding human populations. Due to the effect of the warm and humid climate on human remains, ancient DNA (aDNA) from the North African region has remained largely understudied; only three prehistoric populations from the Upper Paleolithic to the Late Neolithic of the Western North African region have been reported so far (Fig. 1a). The current North African genomic pool has been shaped by genetic influxes from sub-Saharan Africa, Europe, the Middle East, and the Caucasus into an autochthonous ancestral population1. This autochthonous component descends from a population linked to the Upper Paleolithic population from Taforalt (present-day Morocco), dated to around 15,000 years before present (BP). Their genome-wide ancestry is consistent with a substantial Eurasian origin, suggesting a Paleolithic back migration to Africa from Eurasia as proposed before2,3,4. Later Early Neolithic genomes (7000 BP) were genetically similar to the Taforalt population, showing that the first stages of the Neolithic revolution in North Africa were driven by the acquisition of farming techniques by the local population and not by a population turnover5. However, the later phase of the Neolithic was characterized by the movement of people, as Late Neolithic genomes (5000 BP) showed admixture between the local populations and early European farmers5. Nevertheless, to our knowledge, no other genomic information has been obtained for the Western North African region until the late Medieval Period. From the 7th century after the Common Era (CE), the Islamic invasions from the Arabic peninsula changed the cultural and genetic background of most of the local populations6, making it difficult to disentangle the genomic history of the region from the Late Neolithic to the Antiquity.

Fig. 1: Geographical and temporal adscription of the Canary Islands indigenous individuals.



a Available ancient whole-genome data from western North Africa obtained from the literature: Taforalt2, Kehf al Baroud and Ifri n’Amr ou Moussa5; decontextualized individuals from Tenerife and Gran Canaria15, and individuals from Cendro site in Gran Canaria21. b Geographical adscription of the archaeological sites considered in this study. Individuals from the Canary Islands with no archaeological site adscription are not included in b: five previously published individuals from Gran Canaria and Tenerife15 and an individual from Fuerteventura generated in this study. c Available radiocarbon data for the Canary Islands indigenous genomes. The dotted line in c indicates the start of the Castilian conquest (1402). The darker grey tile indicates the period in which the indigenous people of the Canary Islands were in contact with European seafarers. Previously published genomes are indicated in grey while genomes generated in this study are indicated in other colors. Maps made with Natural Earth (https://naturalearthdata.com).



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