Iberia was also relatively warm during the last Ice Age, between 18,000 and 24,000 years ago, presenting a more welcoming climate for animals and people who retreated from the rest of Europe.
…The researchers also discovered that between 8000 BC and 5500 BC, Iberia’s hunter-gatherers were genetically different from each other. This suggests that they interacted with a different group of hunter-gatherers during the Mesolithic era before Anatolian farmers, or those from what is presently Turkey, moved to Iberia and transformed the area yet again. The farmers also mixed with hunter-gatherers, according to their DNA
…Beginning in 2500 BC, the researchers discovered, Iberians were joined by people from central Europe whose showed genetic ancestry from the Russian steppe. And over a few hundred years, the locals and the central Europeans interbred.
Before this, there is no evidence that locals came into contact with anyone from outside the area. But that changed after 2000 BC, when 40% of Iberian ancestry and 100% of the fathers in the study could be traced back to central Europe.
…The research also sheds light on why the language and culture of present-day Basques are so distinct from those of Iberians. The modern people of Basque Country, in northern Spain, are genetically similar to the Iberian Iron Age people with ancestry from the Russian steppe. While people around them mixed with different groups and changed, the Basques held on to their heritage.
…Genetic data will need a boost from what anthropology and archaeology can show about the underlying causes for why this Y chromosome shift happened, the researchers said.