Sorry, here' the whole thing:
A genetic analysis has revealed that, about 4500 years ago, part of southern Europe was conquered from the east. In what is now Spain and Portugal, the local male line vanished almost overnight, and males from outside became the only ones to leave descendants.
David Reich of Harvard Medical School in Boston, Massachusetts presented the results on Saturday at
New Scientist Live in London, UK.
Reich and his colleagues have spent the last few years reading the DNA of people who lived in Europe and Asia several thousand years ago, to track past migrations.
Archaeology had already revealed that
modern humans first entered Europe about 45,000 years ago – at which point the Neanderthals that had been living there for tens of thousands of years vanished. The first modern humans in Europe were hunter-gatherers.
About 9000 years ago a second wave of modern humans arrived from the region around modern Israel and Jordan. These were farmers and at first they lived alongside the hunter-gatherers, with the
two cultures remaining separate. Hunter-gatherers could simply move to a new area if a disagreement with a neighbouring group arose. But because the farmers settled down in specific places and invested time and effort in the land, disputes could escalate. By 7000 years ago
there is evidence of massacres.
Then
beginning around 5000 years ago another group of people entered Europe. It’s this group that Reich’s team focused on.
Steppe out
The new population arose “in far eastern Europe on the steppes north of the Black and Caspian Seas,” Reich said. Archaeologists call them the
Yamnaya. They were pastoralists who relied on grazing animals rather than growing crops.
“The wheel had shortly before been invented and the horse domesticated,” Reich said. The Yamnaya hitched horses to wagons and used them to carry supplies out into the open steppe, allowing them to tend large grazing herds and exploit the steppe better than anyone before.
Before the Yamnaya arose, a host of different cultures existed on the steppe, each of which left behind distinctive artefacts. Most of these groups then disappeared and were replaced by a homogenous Yamnaya culture.
“These people spread over a vast territory from Mongolia to Hungary and into Europe, and are the single primary most important contributors to Europeans today,” Reich said. Only after the Yamnaya arrived do the ancient genomes start to resemble those of modern Europeans. Reich also suggested that
the Indo-European languages – a vast group including most modern European languages – was first brought into Europe by the Yamnaya.
Around the same time, people in the vicinity of Spain began making distinctive beakers. These seem to be associated with a set of religious beliefs, known as the Bell Beaker Culture. It first spread by word of mouth, until the incoming Yamnaya adopted it – at which point it became a marker of their expansion.
Replacement
In February, Reich’s team showed
what happened when the Yamnaya’s descendants arrived in Britain 4500 years ago. Within a few hundred years, about 90 per cent of the local gene pool was replaced.
The people who made Stonehenge were seemingly wiped out, and few of their genes have survived to the present day. The previous style of artefacts was replaced by Bell Beaker Culture. It’s not clear what happened, but the newcomers may have carried unfamiliar diseases that wiped out the locals. The climate was shifting at the time, which might have added to the problems the locals experienced.
Now the team has examined what happened on the Iberian peninsula. The Yamnaya’s descendants began mixing with the locals from 4500 years ago. The resulting population had 40 per cent Yamnaya ancestry and 60 per cent local ancestry. So unlike Britain, many of the original farmers managed to pass on their genes.
But that’s not the complete story. The team found a dramatic shift in the Y-chromosomes, which are only carried by males. “There’s a complete Y-chromosome replacement,” Reich said. The original males’ DNA vanished from the gene pool. “That means males coming in had preferential access to local females, again and again and again,” Reich said.
This looks like a violent conquest, in which an invading army killed or enslaved the local males and took the local females for their own. “The collision of these two populations was not a friendly one, not an equal one, but one where the males from outside were displacing local males and did so almost completely,” Reich said.
This could
only have happened if society had come firmly under the control of the males, with females being treated as second-class citizens or even property – unlike the more egalitarian hunter-gatherer societies that had long since disappeared.
The new findings are in line with results reported in July 2017 by
Rui Martiniano, now at the University of Cambridge, and his colleagues, based on the genomes of 14 ancient people. They also found that the local Y-chromosomes were rapidly replaced in Iberia,
suggesting a male-dominated incursion.