Whether in the garden, on the farm or in the middle of the city: Sparrows feel at home almost everywhere – the main thing is, there are people nearby. Gene analyzes now provide interesting insights into the history of the development of our faithful companions. They show that the species of sparrow common in our country joined the human being some 10,000 years ago and has noticeably adapted to living in our immediate neighborhood over time. At the same time, the story of the sparrows reflects a part of our own history, as researchers report.
Wherever humans are, he too is not far away: the house sparrow (Passer domesticus domesticus) watches us from the garden fence, broods in the niches under our roofs and diligently picks up our dropped crumbs from the ground. As a so-called cultural successor, he is perfectly adapted to life in the immediate vicinity of man. Its original homeland is human settlements in Western and Central Europe. Because he occasionally accompanies us on our travels, the sparrow can now be found in southern Africa, Australia, New Zealand and America. The little songbird is as familiar to us as probably no other – and yet we know surprisingly little about its history. Where are its evolutionary roots? When did he come to Europe? And when did he discover the coexistence with man ?
To learn more about these backgrounds, Mark Ravinet of the University of Oslo and his colleagues have now taken a look at the genome of the house sparrow. They compared the genome of “our” sparrow with that of closely related species. In addition to the willow sparrow and the Italian sparrow, the scientists also took a close look at Passer domesticus bactrianus. This species, which is common in Iran and Kazakhstan, is considered a subspecies of the house sparrow native to Europe but shows a distinctly different behavior. As a result, is less well-off when dealing with people, and in the middle of villages or towns. In addition, migrates in the winter in the south, instead of staying like our sparrow on the ground.
A new ecological niche
The gene comparison provided an explanation for these striking differences. Accordingly, the lineages of these two subspecies already separated about 11,000 years ago. The subspecies Passer domesticus domesticus, which spreads here today, spread as far as Europe, where over time the birds adapted more and more to a life close to humans. Interestingly, this development coincided with a formative period in human history, as the researchers report: the Neolithic Revolution. Former hunter-gatherers began farming, stockpiling and settling down. Exactly this created a new ecological niche that the sparrow knew how to occupy.
In the neighborhood of human settlements with their fields and well-filled granaries, songbirds found optimal conditions. Gradually, this new habitat also left its mark on their genetic material. Especially in two species, the genome of European house sparrows differs significantly from that of its relative from Asia: In genes COL11A and AMY2A on chromosome 8, Ravinet and his colleagues found presumptive effects of natural selection. Thus, mutations in the COL11A gene ensure that our sparrows have a more robust skull and beak – possibly adapting to new diets.