After the last great ice age, humans flooded Europe like slow, creeping tides.
New research suggests that some of these mass migrations may have altered the landscape more than others. And, oddly enough, the biggest impact was not from the people we might expect.
By comparing the timing of significant migrations to changes in vegetation, researchers in the UK found the first farming communities that existed before the land had amazing environmental impacts.
The same cannot be said for the second wave of Bronze Age migrants traveling westward from the Russian steppes, whose movements were associated with a sharp decline in deciduous forests and an increase in pastures and steppes.
The study relies on a number of assumptions and caveats, so some caution is required. With this in mind, the results add to the new history of Europe, transformed by successive waves of cultures representing new languages, new genes and new ways of surviving.
Pull on the genetic tapestry of modern Europe and you will quickly find strands leading to various cradles around the Asian continent.
One of the oldest routes ran from the Anatolian Peninsula, where Turkey is now located.
The DNA left behind by this Neolithic wave of Anatolian farmers can still be found in modern European populations, along with the genetic legacy of other mass migrations.
Scientists have used publicly available ancient and modern genome research to create a map showing the distribution of three different genetic populations across Europe over the centuries.
One of these consisted of the original hunter groups that established themselves in the European landscape after the Ice Age. The second was the Anatolian farmers who went further.
The third population is today referred to as Yamnaya Kultura, a name borrowed from the Russian word for 'yama' in connection with the method of burying the dead.
These people moved to Europe during the late Copper and early Bronze ages over 5,000 years ago, leaving the lands north of the Black Sea and bringing with them relatively advanced horse and wheel technology, not to mention a talent for digesting milk.
Comparison of the distribution method for each of the gene pools revealed a significant difference in the speed of the two migrations.
Perhaps it was no surprise to anyone that the Yamnaya Bronze Age migration took much less time to settle than Anatolian farmers. No doubt the presence of horses helped, but there is also the possibility that the ground is already traversable.
Close examination of land cover maps and climatic variables did not reveal any significant shifts in vegetation species.
The researchers note that other studies have identified local environmental impacts in some parts of the continent, but in general their impacts did not appear to be widespread.
When it comes to Bronze Age migration, the changes were comparatively dramatic, with large-scale deforestation and the creation of pastures.
“As these peoples moved west, we see an increase in rangelands and a decrease in deciduous forests across the continent,” says geogeneticist Fernando Razimo of the University of Copenhagen.
It is important to remember that causation is difficult to prove. Climate change could also play a key role in the development of ecology, laying out feeding grounds for horses and opening up land for travel.
But the models used by the researchers strongly suggest that growing populations along the Bronze Age migration path were responsible for the vegetation change.
Relying on DNA data with its known features leaves much room for discussion, as does the potential for untested variables to cause changes in European vegetation.
The history of Europe's past is far from complete, but each new detail adds new insights into how the cultures of the past may have affected the landscape as they move, telling us one or two things about how the earth will continue to change in the future.
“European landscapes have changed radically over thousands of years,” says Jesse Woodbridge, a geographer at the University of Plymouth in the UK.
“Knowing how people interacted with their environment in the past is essential to understanding how people use and affect the world today.”
This study was published in PNAS.
Sources: Photo: sciencealert
