Being part of a small hunter - gatherer kindred can really define your selection when it follow to finding a mate , specially if most of the people in your kinship group are your own brothers and sister . According to the upshot of a new transmissible study , Europe ’s last Stone Age forager produce around this trouble by making certain to mix with non - related to Orion - collector , thus preventinginbreedingwhile also keeping light of the get Neolithic farmer universe .

Researchers sequenced the genomes of 10 skeletons find at the iconic Stone Age web site of Hoedic , Téviec , and Champigny , in France . fit in to the study authors , these ancient settlements are known for their “ unusually well - preserved and rich burials . ”

carbon 14 dating of the collagen in the osseous tissue confirmed that all of the skeletons were more or less 6,700 year old , and therefore hailed from the period when the Mesolithic gave path to the Neolithic , ashunter - gatherergroups were put back by land community . “ These circumstances could have cornered these radical into serious genetic drift due to extremely little universe size , leaving no option to cognation and itsdeleterious consequences , ” write the researcher .

This grim outlook is tone by the fact that all three land site contain shared graves , with multiple individuals eat up alongside one another . Such a drill was unusual for this period of the Stone Age and has previously been render as grounds that these people were blood relation .

contradict this narrative , however , work author Dr Amélie Vialet explain in astatement , " Our results show that in many cases – even in the case of women and children in the same grave accent – the individual were not concern . This suggests that there were strong social bonds that had nothing to do with biological kinship and that these relationship remained important even after death . ”

Isotopic information was then used to confirm that the inhabitant of each site existed as distinct groups . For instance , higher stage of marine proteins in the bones from   Hoedic indicates that the subsistence and dietary practices of these individuals disagree from those of   Téviec and Champigny .

base on this isotopic data , the cogitation authors determined that some of the women at Hoedic were raised on planetary proteins before switching to a more hard marine dieting later in lifespan . This advise that char were commute between different huntsman - collector groups , probably as a means of preventing inbreeding .

" Our genomic analyses show that although these group were made up of few individuals , they were generally not close touch , ” say study author Luciana G. Simões . “ Furthermore , there were no sign of inbreeding . ”

“ However , we know that there were discrete social unit – with dissimilar dietary use – and a pattern of group emerge that was probably part of astrategy to avoid inbreeding , " Simões added .

antecedently , it had been suggested that some of the woman buried at these sites were actually raised in husbandry settlements – where they would have consume more sublunary animals – before later on being take in into hunter - gatherer groups . However , based on theirgeneticanalysis , the investigator confirm that “ these females [ … ] did not come from Neolithic populations , as they are within the [ hunter - gatherer ] genetic edition and show no traces of Neolithic farmer - related stock . ”

“ Hence , contrary to former conclusions ground on static isotope data from the same sites , the Late Mesolithic forager biotic community was limited in mate - exchange to neighboring hunter - gatherer groups , to the exclusion of Neolithic sodbuster , ” they write .

In conformity with these result , the researchers are able to present a more accurate delineation of the interaction between the last huntsman - gatherers and first farmers to absorb westerly Europe . More specifically , they show that any gene menstruation that may have occurred between the two groups was “ unidirectional   and resulted from individuals with [ huntsman - collector ] line joining farmer groups and not the other way around ” .

The study is issue in theProceedings of the National Academy of Sciences .