Model of two ancient humans. Credit: Genetic Literacy Project

Prehistoric Humans are Likely to Have Formed Sex Networks to Avoid Inbreeding

(Read the article on one page)

Early humans seem to have recognized the dangers of inbreeding at least 34,000 years ago, and developed surprisingly sophisticated social and mating networks to avoid it, new research has found.

The study, reported in the journal Science, examined genetic information from the remains of anatomically modern humans who lived during the Upper Paleolithic, a period when modern humans from Africa first colonized western Eurasia. The results suggest that people deliberately sought partners beyond their immediate family, and that they were probably connected to a wider network of groups from within which mates were chosen, in order to avoid becoming inbred.

This suggests that our distant ancestors are likely to have been aware of the dangers of inbreeding, and purposely avoided it at a surprisingly early stage in prehistory.

The symbolism, complexity and time invested in the objects and jewelry found buried with the remains also suggests that it is possible that they developed rules, ceremonies and rituals to accompany the exchange of mates between groups, which perhaps foreshadowed modern marriage ceremonies, and may have been similar to those still practiced by hunter-gatherer communities in parts of the world today.

Detail of one of the burials from Sunghir, in Russia. The new study sequenced the genomes of individuals from the site and discovered that they were, at most, second cousins, indicating that they had developed sexual partnerships beyond their immediate social and family group. Credit: By José-Manuel Benito Álvarez

Detail of one of the burials from Sunghir, in Russia. The new study sequenced the genomes of individuals from the site and discovered that they were, at most, second cousins, indicating that they had developed sexual partnerships beyond their immediate social and family group. Credit: By José-Manuel Benito Álvarez (Own work) [Public domain], via Wikimedia Commons

The study's authors also hint that the early development of more complex mating systems may at least partly explain why anatomically modern humans proved successful while other species, such as Neanderthals, did not. However, more ancient genomic information from both early humans and Neanderthals is needed to test this idea.

The research was carried out by an international team of academics, led by the University of Cambridge, UK, and the University of Copenhagen, Denmark. They sequenced the genomes of four individuals from Sunghir, a famous Upper Paleolithic site in Russia, which is believed to have been inhabited about 34,000 years ago.

The human fossils buried at Sunghir represent a rare and highly valuable, source of information because very unusually for finds from this period, the people buried there appear to have lived at the same time and were buried together. To the researchers' surprise, however, these individuals were not closely related in genetic terms; at the very most, they were second cousins. This is true even in the case of two children who were buried head-to-head in the same grave.

Artist’s reconstruction of one of the Sunghir burials. Illustration © Libor Balák

Artist’s reconstruction of one of the Sunghir burials. Illustration © Libor Balák

Professor Eske Willerslev, who holds posts both as a Fellow at St John's College, Cambridge, and at the University of Copenhagen, was the senior author on the study. "What this means is that even people in the Upper Paleolithic, who were living in tiny groups, understood the importance of avoiding inbreeding," he said. "The data that we have suggest that it was being purposely avoided."

"This means that they must have developed a system for this purpose. If small hunter-gatherer bands were mixing at random, we would see much greater evidence of inbreeding than we have here."

Early humans and other hominins such as Neanderthals appear to have lived in small family units. The small population size made inbreeding likely, but among anatomically modern humans it eventually ceased to be commonplace; when this happened, however, is unclear.

"Small family bands are likely to have interconnected with larger networks, facilitating the exchange of people between groups in order to maintain diversity," Professor Martin Sikora, from the Centre for GeoGenetics at the University of Copenhagen, said.

Museum of Natural History - Early Hominids

Museum of Natural History - Early Hominids (Credit:  Strannik45 / flickr  )

Sunghir contains the burials of one adult male and two younger individuals, accompanied by the symbolically-modified incomplete remains of another adult, as well as a spectacular array of grave goods. The researchers were able to sequence the complete genomes of the four individuals, all of whom were probably living on the site at the same time. These data were compared with information from a large number of both modern and ancient human genomes.

They found that the four individuals studied were genetically no closer than second cousins, while an adult femur filled with red ochre found in the children's' grave would have belonged to an individual no closer than great-great grandfather of the boys. "This goes against what many would have predicted," Willerslev said. "I think many researchers had assumed that the people of Sunghir were very closely related, especially the two youngsters from the same grave."

Comments

riparianfrstlvr's picture

The Navajo were clan breeders by tradition. during the eventual internment and the "long walk" to Ft. Sumner their population bottlenecked. as a result of this bottleneck and their tradition of clan marriage they have been cursed with a genetic anomaly known as xeraderma pigmentosa. it normally affects about 1 in a million, but with the Navajo it affects about 1 in 250. today becuase of this clan marriage is not recommended by genetecists studying this xp.

while ancient people didn't understand the mechanics of genetics, during population bottlenecks, climate change and other natural disasters, they did learn that inbreeding may produce offspring with 3 heads sharing a single eyeball. of course i exaggerate but our ancestors did know how to figure stuff out, they were not stupid

riparianfrstlvr

Wasn't it also one of the desert tribes in the Four Corners [Navajo maybe?] that you could marry outside of clan [like Bear could marry anybody but Bear clan] so it was fairly exogamous?

Eskimo tribes when early explorers first encountered them would invite them to sleep with their women and consider it an insult if they refused. I always felt it was their way of taking advantage of any available new gene pool.

Register to become part of our active community, get updates, receive a monthly newsletter, and enjoy the benefits and rewards of our member point system OR just post your comment below as a Guest.

Top New Stories

Myths & Legends

Human Origins

Map of sites and postulated migratory pathways associated with modern humans dispersing across Asia during the Late Pleistocene.
Most people are now familiar with the traditional "Out of Africa" model: modern humans evolved in Africa and then dispersed across Asia and reached Australia in a single wave about 60,000 years ago. However, technological advances in DNA analysis and other fossil identification techniques, as well as an emphasis on multidisciplinary research

Ancient Technology

The four-handled tureen adorned with dragons, birds and spikes
Chinese archaeologists have discovered ritual tureen and “soup bowls” next to a badly decomposed body in a Zhou dynasty-era tomb. Among the remains there were also uncovered two wine vessels, which experts suggest were probably used as part of the funerary rituals.

Ancient Places

Illustration of the "Emmons mask", a Mississippian culture carved cedarwood human face shaped object once covered in copper and painted with galena and used as part of a headdress
The City of Moundsville is located along the Ohio River in Marshall County, West Virginia. From the time of European settlement in the 1770s, Moundsville was regarded by antiquarians as one of the most significant ancient sites in North America. For it was here that the Adena mound builders and their descendants constructed the largest ceremonial center in the Upper Ohio Valley

Our Mission

At Ancient Origins, we believe that one of the most important fields of knowledge we can pursue as human beings is our beginnings. And while some people may seem content with the story as it stands, our view is that there exists countless mysteries, scientific anomalies and surprising artifacts that have yet to be discovered and explained.

The goal of Ancient Origins is to highlight recent archaeological discoveries, peer-reviewed academic research and evidence, as well as offering alternative viewpoints and explanations of science, archaeology, mythology, religion and history around the globe.

We’re the only Pop Archaeology site combining scientific research with out-of-the-box perspectives.

By bringing together top experts and authors, this archaeology website explores lost civilizations, examines sacred writings, tours ancient places, investigates ancient discoveries and questions mysterious happenings. Our open community is dedicated to digging into the origins of our species on planet earth, and question wherever the discoveries might take us. We seek to retell the story of our beginnings. 

Ancient Image Galleries

View from the Castle Gate (Burgtor). (Public Domain)
Door surrounded by roots of Tetrameles nudiflora in the Khmer temple of Ta Phrom, Angkor temple complex, located today in Cambodia. (CC BY-SA 3.0)
Cable car in the Xihai (West Sea) Grand Canyon (CC BY-SA 4.0)
Next article