Neanderthal bones: Signs of their sex lives
Inbreeding leads to a problematically small gene pool.
The site is infamous among anthropologists who study the Paleolithic period for the evidence of what appears to be the massacre and possible cannibalization of a family: Their bones seem to have been hacked at by stone tools and hammers, probably by another group of Neanderthals, to remove their flesh and marrow.
But more importantly, for this story, those bones also reveal something of the sex life of the cave's inhabitants. Anomalies and deformations, along with the DNA buried within their bones, suggest that the members of this group (and their parents) were mating with their close kin.
Lately, much news from the field of paleoarchaeology and anthropology has centered on Neanderthal bedfellows. You would be forgiven for thinking that paleoanthropologists think about little other than paleo-sex. Within the past several years, genetic evidence has emerged that Neanderthals interbred on more than one occasion with both anatomically modern humans and our newfound ancient relative, the Denisovans. One finger bone fragment from Denisova Cave in Siberia is now famous for belonging to a teenage girl who had a Neanderthal mother and a Denisovan father.
But evidence also shows that while some Neanderthals were apparently breeding well outside of the family group, some were also finding mates much closer to home.
In the remains from El Sidrón Cave, paleoanthropologist Luis Ríos and colleagues found 17 examples of congenital anomalies—structural malformations of various body parts that occur while an individual is developing in the womb.
One young El Sidrón individual, for example, had an oddly shaped patella, the bone that forms the kneecap: It had three lobes rather than just one. This Neanderthal probably had a limp. An adult male in the same cave had a markedly narrow nasal passage and a "retained deciduous mandibular canine," writes Ríos and his co-authors—this adult Neanderthal never lost one of his lower canine baby teeth. That tooth developed a painful cyst, which left its mark on the bone of his jaw. Microscopic striations on the tooth itself suggest that he coped with the pain by avoiding chewing on that side of his mouth.
One possible explanation for these skeletal abnormalities is that they resulted from extremely stressful environmental conditions, such as brutally cold weather and scarce food. A pregnant mother experiencing a lot of physical stress and nutritional deprivation might give birth to an infant with some of the same conditions seen at El Sidrón.
Inbreeding leads to a problematically small gene pool
But DNA tests from these bones indicate that inbreeding and a small population size were likely factors contributing to the physical peculiarities in this family. The 13 El Sidrón Neanderthals share much longer segments of their DNA than would be expected if they were the offspring of non-relatives.
Genetically, the three adult males in the group were closely related enough to be brothers, cousins, or uncles, while the four adult females in the group came from three distinct genetic lines. While all individuals were likely distantly related to one another (think third or fourth cousins), it is likely that the males exchanged females with another local, slightly less closely related group.
Today inbreeding carries connotations of "kissing cousins" or intimacy between even closer familial relations. But the term simply means mating between relatives, which increases the number of common ancestors in a family tree and the likelihood of inheriting deleterious genes from those common ancestors. Even third or fourth cousins are genetically similar enough for issues to arise.
The younger El Sidrón individuals (ranging in age from 5 to 15 years of age, along with one infant) were likely the offspring of at least some of the adults. At least one of these children, the young male mentioned above, possessed skeletal malformations that were likely passed down from parents who were fairly closely related.
The tangled familial ties of the El Sidrón Neanderthals are not a unique situation; DNA evidence from other Neanderthals elsewhere in Eurasia also shows elevated instances of shared DNA segments around this time, suggesting that mating between individuals who shared recent ancestors was fairly frequent, and possibly unavoidable, if local populations were small.
In general, inbreeding leads to a problematically small gene pool. Rare harmful traits that might disappear in larger populations tend to be amplified if close kin interbreed. Yet inbreeding has happened throughout human history, especially in the royal families of different cultures. Just look at the Habsburg family line in Spain or the royal families of Ancient Egypt to see the effects of keeping family bloodlines "pure."
Neanderthals were not the only ancient hominins to mate with their close relatives. Anatomically modern humans have also been found with skeletal evidence of inbreeding, such as abnormally bowed thigh bones, deformed arm bones, and even a case of a toddler with a swollen brain case consistent with hydrocephalus.
At the time that these congenital malformations appear, between 100,000 and 50,000 years ago, modern humans were traveling out of Africa. They fanned out across vast geographical regions, and, at times, were quite isolated from one another. Populations might have been separated by hundreds of kilometers at a time, only rarely encountering one another. This might be a simple reason why inbreeding occurred: Pickings were slim.
During the time that the El Sidrón Neanderthal family occupied their cave, it is likely that they were also fairly isolated. Their mating patterns probably had much more to do with small population size and low population density than any sort of cultural practice. There is no way to know if cultural taboos against mating with close relatives existed back then.
Interestingly, most of the individuals in the El Sidrón family group lived well past infancy despite physical conditions that, in some cases, would have made it difficult for them to get around and perform their day-to-day tasks. This family cared for one another, sharing physical burdens and helping each other to survive. Their relations, and their care, are recorded in their bones.
This column is part of an ongoing series about the Neanderthal body: a head-to-toe tour. See our interactive graphic.
- Ancient Neanderthal DNA Shows What They Ate—And Who They ... ›
- Sex with Neanderthals helped modern humans survive, says study ... ›
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Whether or not women think beards are sexy has to do with "moral disgust"
- A new study found that women perceive men with facial hair to be more attractive as well as physically and socially dominant.
- Women tend to associate more masculine faces with physical strength, social assertiveness, and formidability.
- Women who display higher levels of "moral disgust," or feelings of repugnance toward taboo behaviors, are more likely to prefer hairy faces.
Beards and perceptions of masculinity<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjU5OTg0MC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0NzkxMjM3N30.cH-GqNwP5GVqvstgJWAhBPn1B_lYpVEAI0I7iax7EQw/img.jpg?width=1245&coordinates=0%2C1900%2C0%2C849&height=700" id="caae6" class="rm-shortcode" data-rm-shortcode-id="cb0a355a4e8e1899789bc45f3f7aef56" data-rm-shortcode-name="rebelmouse-image" />
Photo Credit: Wikimedia<p>The study used 919 American (mostly white) women ages 18-70 who rated 30 pictures of men they were shown with various stages of facial hair growth. The photographs depicted men with faces that had been digitally altered to look more feminine or more masculine, with a beard and without a beard. The women rated the men according to perceived attractiveness for long-term and short-term relationships. The study found that the more facial hair the men had, the higher the men were rated on their attractiveness, particularly for their suitability for a long-term relationship.</p><p>Part of this might be attributed to facial masculinity — i.e. protruding brow ridge, wide cheekbones, thick jawline, and deeply set narrow eyes — which conveys information to a woman about a man's underlying health and formidability. Women tend to associate more masculine faces with physical strength and social assertiveness. It can also indicate a man with a superior immune response. The researchers suggested that their findings favoring bearded men could be due to the fact that facial hair enhances the masculine facial features on a man's face, like creating the illusion of a thicker jaw line. This could communicate direct benefits to women like resources and protection that would enhance survival among mothers and their infants. In other words, while a beard doesn't mean superior genetics in and of itself, it might be a primitive, ornamental way of saying, "Hey girl, I'm a testosterone-fueled lean, mean, pathogen fighting machine." <br></p><p>It could also be that a beard becomes its own destiny. The researchers in this study cite prior research that found that by growing a beard, men felt more masculine and had higher levels of serum testosterone, which was linked to a higher level of social dominance. They also tended to subscribe to more old-school beliefs about gender roles in their relationships with women as compared to men with clean-shaven faces.<span></span><br></p>
What does disgust have to do with beard preference?<p>Obviously, not all women dig beards. The researchers were particularly interested in what traits make a women prefer bearded men over clean-shaven faces. They looked into several factors including a woman's disgust levels on various concepts, her desire to become pregnant, and her exposure to facial hair in her personal life. </p><p>According to the study, women who were not into facial hair were turned-off by potential parasites or other critters they imagined could be in the hair or skin. Women ranking high on this "ectoparasite disgust" scale might have viewed beards as a sign of poor grooming habits. However, women who ranked higher in levels of "pathogen" did find the bearded men to be desirable, possibly because they perceived beards as a signal of good health and immune function. An intriguing discovery in the study was links to morality. Women who displayed higher levels of "moral disgust," or feelings of repugnance toward taboo behaviors, were more likely to prefer hairy faces. The authors opined that this could reflect a link between beardedness, politically conservative outlooks, and traditional views regarding performances of masculinity in heterosexual relationships.</p>
Additional findings<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjU5OTg1My9vcmlnaW4uZ2lmIiwiZXhwaXJlc19hdCI6MTYyNDI1NjUyOX0.P9B8WbmJR0q4nfzYZKbuNSA-2SAigVWJgrQE-_Gxlds/img.gif?width=980" id="49143" class="rm-shortcode" data-rm-shortcode-id="2ed3b1d6f20fc170bf2974646e565e8d" data-rm-shortcode-name="rebelmouse-image" />Giphy<p>The correlations that existed between married and single women's rating on the attractiveness of beards were not particularly clear, although the researchers noted that single and married women who wanted children tended to find beards more attractive than the women who didn't want children. They also found that women with bearded husbands found beards to be more attractive, which might indicate that social exposure to beards influences how desirable they are perceived of as being. Or it could be that men with wives who like beards grow beards.</p><p>It's important to note that culture plays a huge role in how attractive women perceive certain male characteristics as being. This study looked at a small, culturally specific group of American women, so no big, universal claims should be made about masculinity, facial hair, and male desirability to women. However, research like this is important in highlighting how human grooming decisions are driven by much more than fashion trends. Sociobiological, economic, and ecological factors all play a part in the way we choose to present ourselves.</p>
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