Central Europe's indigenous hunter-gatherers and immigrant farmers lived alongside each other for more than 2,000 years before the former took up agriculture, a new study suggests.

Published in the journal Science, the report looked at bones from a cave near Hagen in Germany where individuals from both groups were buried.

"It is commonly assumed that the Central European hunter-gatherers disappeared soon after the arrival of farmers," Ruth Bollongino, lead author of the study and researcher from the Johannes Gutenberg University Mainz, explained in a statement. "But our study shows that the descendants of Mesolithic Europeans maintained their hunter-gatherer way of life and lived in parallel with the immigrant farmers, for at least 2,000 years. The hunter-gathering lifestyle thus only died out in Central Europe around 5,000 years ago, much later than previously thought."

All central Europeans were hunter-gatherers until roughly 7,500 years ago when immigrant farmers arrived, according to previous genetic studies carried out by Mainz researchers. Little in terms of an archaeological record exists for a hunter-gathering lifestyle after this point, leading many to assume that those practicing it either died out or transitioned into a farming lifestyle.

For years, the nature of the relationship between these nomadic and sedentary groups has remained a mystery. The new study shows that the populations remained in close contact for thousands of years, intermarrying and burying their dead along side each other.

Interestingly, the intermarriage was one-directional: while hunter-gatherer women sometimes married into the farming communities, no genetic lines of farmer women could be found among the hunter-gatherers.

The phenomenon, explains anthropologist Professor Joachim Burger, is one that can be seen today.

"This pattern of marriage is known from many studies of human populations in the modern world," Burger said. "Farmer women regarded marrying into hunter-gatherer groups as social anathema, maybe because of the higher birthrate among the farmers."

Based on their results, population geneticist Adam Powell argues that both groups influenced the modern European gene pool.

"Neither hunter-gatherers nor farmers can be regarded as the sole ancestors of modern-day Central Europeans," he said. "European ancestry will reflect a mixture of both populations, and the ongoing question is how and to what extent this admixture happened."