Neandertal Social Groups

Very rarely is an entire family group of hominins buried and fossilized at the same time. It is even rarer for paleoanthropologists to discover such an assemblage. Fortunately for science but unfortunately for the hominins, caves occasionally collapsed on entire social groups.

Map of El Sidrón

At a site known as El Sidrón in Spain, excavations have been ongoing since 2000. To date, 12 Neandertals have been discovered in a context that points to a single geological event, circa 49,000 years ago. A group of 12 Neandertals is consistent with previous estimates of around 10 individuals per group.  At least six adults, three adolescents and four younger individuals were buried at once, most likely during a storm. The cold conditions of the cave system and immediate burial of the remains not only preserved the bones well, but were also ideal for DNA.

The remains were sexed based on both morphology and DNA analysis. After sex was determined, anthropologists identified the different Neandertal lineages based on mitochondrial DNA. Several of the adults were found to be male, and the other three female. It was discovered that all three males belong to the same matrilineal group, while each respective female has a different haplotype. When compared to modern Europeans, the authors noted that there is significantly less genetic diversity within the mitochondrial genome.

These results strongly imply that Neandertals exhibited patrilocal mating behavior. Females were the ones who would have changed family groups, not males. This type of insight into an extinct species is unique, thanks to the quality of DNA preservation available at El Sidrón.

Another interesting point of discussion in the study relates to Neandertal interbirth interval. One of the females was linked by DNA to two of the younger individuals, approximately several years apart in age. If the anthropologists are correct about the relationship, this puts the interbirth interval for Homo neanderthalensis at a value similar to hunter-gatherer groups today. This data, if replicated with other Neandertal individuals, could eventually dispel differential reproduction as a potential cause for Neandertal disappearance.

Knowing about Neandertal group dynamics could provide crucial clues as to why they went extinct. Future analysis of the remains recovered at El Sidrón will no doubt give more insights into our closest extinct relatives, and perhaps even why Homo sapiens flourished and Neandertals declined.

By Matthew Magnani

Lalueza-Fox, C., et al. (2011). “Genetic evidence for patrilocal mating behavior among Neandertal groups.” PNAS . January 4, vol. 108 no. 1 250-253.

8 thoughts on “Neandertal Social Groups

  1. Thank you for your clear rendition of events at El Sidron and their provisional interpretation. Much appreciated. Two Q: 1. What does it signify that mitochondrial evidence is less diverse in the El Sidron remains from modern humans? 2. Hominin, hominid, homonim…which?

    1. A smaller mitochondrial DNA pool could indicate that the Neandertals went through some kind of population bottleneck, reducing their numbers and genetic diversity. However, the population of El Sidrón would have been less genetically diverse because they were more closely related to begin with (which is discussed in the original article by the authors).

      I hope this can answer your second question.The hominin/hominid game is all based in the changing understanding of relation between species. Once it was found that chimps are more closely related to Homo sapiens, the names got shuffled around. Right now it is safe to use hominin for human ancestors, but you can still use the old classification of hominid.

      Hominoidea refers to humans, great apes and gibbons. The subfamily Homininae (hominines) includes chimps and humans. Humans (and ancestors) have been placed in a “Tribe” known as Hominini, which is the origin of the word “hominins” today.

      Thank you for your questions,
      Matthew Magnani

  2. Are there any results on other inter-group genetic relationships? Between the younger members and the adult males, or the other adult females? And the estimated age range of the adults? And where the adolescents fit in genetically? If two of the younger members don’t have genetic links with other individuals in the cave (I’m surmising, as only two were mentioned as having them), what might this suggest? That their parent/parents died before the event that buried these group members, perhaps, or they came from a different family group? Sorry for all the questions – this is fascinating, but so tantalising.

  3. this post had me thinking: 12 individuals is a lot of meat, this plus that fact the bones were not all in one big pile but in separate piles would maybe indicate they were eaten as needed? Which leads to the point that they were captive? And finally as the bones were deep in a cave, was this an attempt to hide the evidence?

  4. i wonder if the accident theory has virtue. if 12 people died in an accident, and were eaten after, the group must have been as much bigger. to me seems that a lack of carnivore activity tells humans were there rather in a matter of hours then days. the research suggests that the event took place outside , and not deep in a cave, i saw no mention they were in seperate piles (rather the opposite 6 m2 is hardly enough to pile up 12 humans remains in seperate piles)all in all i am curious to a more accurate description of the location and finds in situ.

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