The rocks of Chagyrskaya Cave picturesquely tower over a river valley in the foothills of the Altai Mountains in Central Asia. Tens of thousands of years ago, groups of Neanderthals used this karst cave in southern Siberia as a hunting camp. Herds of bison, horses and ibex once roamed through the valley. What remains are hundreds of thousands of remains of bones and stone tools along with 80 Neanderthal fossils – and these now provide a unique insight into the social structure of these cousins of modern humans, who inhabited Eurasia from about 430,000 years ago until their extinction about 40,000 years ago . So they lived Neanderthals in manageable groups, namely patrilocal. This means that the men generally stayed at home, while the women left their groups and joined other clans.
This behavior is already dated homo sapiens known. Analyzes in recent years have repeatedly shown that women were more mobile than men here. In the Lechtal south of Augsburg, for example, scientists from Munich, Tübingen and Jena found evidence in 2017 that the men mostly came from the region, while the majority of the women had immigrated from Bohemia or Central Germany. This patrilocal pattern can be traced back over a period of 800 years, up to the Bronze Age. At the Central German Archaeologists’ Day in Halle an der Saale at the beginning of October, the archaeogeneticist Alissa Mittnik, who was involved at the time and now works in Leipzig, spoke of an extensive marriage network that may have strengthened supra-regional relationships. The archaeologist Maïté Rivollat reported similar finds from the Neolithic at Gurgy near Auxerre in France. There, too, the researchers had found genetic evidence that the men stayed in their clans while the women changed their groups.
A Neanderthal father and his teenage daughter lived in the cave, among others
Now it turns out that the Neanderthals, at least from Tschagyrskaya, apparently behaved in a similar way. An international research team headed by Laurits Skov and Benjamin Peter from the Max Planck Institute for Evolutionary Anthropology in Leipzig examined their genome. Also involved was Svante Pääbo, the founder of paleogenetics, who was recently awarded the Nobel Prize in Medicine for research into prehistoric DNA. As the scientists now in the journal Nature to report, they examined the remains of a total of 13 former cave dwellers. Eleven of these men, women, and children lived in Chagyrskaya Cave roughly 54,000 years ago, and two other individuals studied lived a little earlier in the nearby Okladnikov Cave. It is the most extensive study of its kind to date. For comparison: only 18 comparable genome data from Neanderthals from 14 different sites have been published to date. In addition, it is the first analysis of a clearly definable Neanderthal family group.
Because among the eleven Tschagyrskaya individuals, the team identified a father and his teenage daughter. The scientists also found an eight to twelve-year-old boy and an adult woman who could have been his cousin, aunt or grandmother. The analyzes indicate that the Neanderthals inhabited the cave at the same time, so they may have been part of the same community. Because the genetic diversity is very low, the researchers also assume that this community was a family of about 20 individuals. That would be quite a small group; However, as early as 2019, French researchers in Le Rozel in Normandy came to a similar conclusion: There they examined dozens of Neanderthal footprints and concluded that they came from ten to 13 individuals.
Homo sapiens also traveled in small groups as hunters and gatherers. Group size is a balancing act and depends on the environment, says Jean-Jacques Hublin, director emeritus at the Leipzig Institute and not involved in the work. Groups therefore need a minimum size so that they can survive safely and establish a new generation. But they are also not allowed to have more members than they can support.
However, such groups did not necessarily live in complete isolation, but probably in a kind of network with other communities in the area. Another result of the study shows how this could have worked. The team also looked at the genetic diversity on the Y chromosome, which is inherited from father to son, and the diversity of mitochondrial DNA that mothers pass on to their children. It turned out that the mitochondrial genetic diversity was ten times higher than the diversity on the Y chromosomes. The family’s gene pool was refreshed less by foreign men than by the arrival of women. The team suspects that at least 60 percent of the women left their own community and joined other tribes. “The men were more closely related, the women came from outside,” explains Hublin.
The same behavior in mate selection is also found in chimpanzees
Indications of such customs among the Neanderthals had already been described by researchers in 2010 after analyzing fossils in the El Sidrón cave in the northern Spanish region of Asturias. They examined Neanderthal genomes from three women and three men and found that the three adult men came from the same ancestral lineage, but each of the three women came from a different lineage. The researchers already interpreted this as evidence of a patrilocal way of life, but their interpretation was controversial. The new study supports the interpretation at the time, writes Lara Cassidy from Trinity College Dublin in one Nature-Comment on the study: “Skov et al. provide the most compelling evidence of such behavior to date.”
It is unclear whether the researchers’ findings only apply to the inhabitants of the Chagyrskaya Cave or whether they can be generalized to all Neanderthals. But they would not only fit the social structure of early Homo sapiens communities. The same phenomenon is found even in modern humans’ more distant relatives, namely chimpanzees, says Jean-Jacques Hublin. “There, too, the males remain in the group in which they were born.”
With material from dpa.