While the archaic human genomes of our closest relatives, the Neanderthals and the Denisovans, were sequenced in 2010, the oldest recovered modern human DNA to date came from Ötzi the Iceman, a 5,300-year-old mummy found in the Ötztal Alps between southern Austria and northern Italy in 1991.
Now geneticists have successfully extracted mitochondrial DNA (passed down the maternal line) from the 8,000-year-old bones of 2 young adult males, unearthed in a cave high in the Cantabrian mountains of northwestern Spain in 2006. The results are surprising.
They were modern human hunter-gatherers of the Mesolithic period and inhabited the Iberian Peninsula shortly before the arrival of Neolithic farmers originating from the Middle East. However, their DNA suggests that they were not the ancestors of the modern inhabitants of the Iberian Peninsula today, but are actually closer genetically to the current populations of northern Europe – specifically those of the UK, Germany, Lithuania and Poland.
Both hunters-gatherers were of mtDNA haplogroup U5b, which is rare among modern European populations (around 7%), but is present in 12 out of a total of 27 Mesolithic skeletons across Europe that have so far produced DNA.
Modern humans first entered Europe through the Balkans around 40,000 years ago and rapidly dispersed around the continent. The advancing ice sheets of the Last Glacial Maximum (LGM) from around 26,000 years ago forced them to retreat south to milder climate refuges in the Iberian Peninsula, the Balkans and the shores of the Black Sea. When the LGM finally started to abate around 19,000 years ago they emerged from these southern refuges to reoccupy central and northern Europe. Their nomadic lifestyle continued until around 8,000 years ago, when agriculture swept into the continent. Within 3,000 years, the hunter-gatherer way of life had largely disappeared in Europe.
Although the first Neolithic farmers spread quickly across the continent, trading and exchanging culture across thousands of miles, it had been largely assumed that their Mesolithic predecessors lived in small, isolated groups with little inter-tribal contact over long distances. However, the shared mitochondrial lineage between the skeletons in Spain and those in northern Europe suggests a genetically cohesive Mesolithic population which was highly mobile and networked across the continent.
Archaeological evidence suggests that they had close cultural links too. One of the Spanish skeletons was discovered with 24 pierced teeth from a red deer, embroidered on cloth that once covered his body. The use of red deer teeth for personal decoration appears to have been widespread across Europe during the Mesolithic.
Paleogeneticist Carles Lalueza-Fox, of the Spanish National Research Council, told LiveScience,
“These are the oldest partial genomes from modern human prehistory. There are many works that claim the Basques (of the Iberian Peninsula) could be descendants from Mesolithics that became isolated in the Basque country. We found the modern Basques are genetically not related to these two individuals. Despite their geographical distance, individuals from the regions corresponding to the current England, Germany, Lithuania, Poland and Spain shared the same mitochondrial lineage. These hunters-gatherers shared nomadic habits and had a common origin.”