Abrigo do Lagar Velho Dental Study – Neanderthal Hybrid Debate Continues

Dental maturational sequence and dental tissue proportions in the early Upper Paleolithic child from Abrigo do Lagar Velho, Portugal — PNAS

This is a paper in which the authors investigate the dentition of the Abrigo do Lagar Velho child, excavated from a rock-shelter in Portugal, back in November 1998 by Cidália Duarte and João Zilhão, later assisted by Professor Erik Trinkaus. The unusually robust cranial and post-cranial features prompted the researchers to suggest that this specimen, LV1, was a hybrid of Neanderthal and AMH ancestry, a theory which has since come under intense attack from subsequent genetic researchers who contend there is almost no evidence in our modern genome of Neanderthal admixture, especially where mtDNA sequences have been investigated. This in turn has been countered by the argument that it is hardly surprising we see so little evidence tens of millennia later, as the Neanderthal influence could by now simply not have survived intact down through so many generations of humans, due to those direct descendants of limited interbreeding dying out along the way at the expense of AMH – more of which later.

The paper by Priscilla Bayle et al opens with this abstract…

Neandertals differ from recent and terminal Pleistocene human populations in their patterns of dental development, endostructural (internal structure) organization, and relative tissue proportions. Although significant changes in craniofacial and postcranial morphology have been found between the Middle Paleolithic and earlier Upper Paleolithic modern humans of western Eurasia and the terminal Pleistocene and Holocene inhabitants of the same region, most studies of dental maturation and structural morphology have compared Neandertals only to later Holocene humans.

To assess whether earlier modern humans contrasted with later modern populations and possibly approached the Neandertal pattern, we used high-resolution microtomography to analyze the remarkably complete mixed dentition of the early Upper Paleolithic (Gravettian) child from Abrigo do Lagar Velho, Portugal, and compared it to a Neandertal sample, the late Upper Paleolithic (Magdalenian) child of La Madeleine, anda worldwide extanthumansample.Someaspects of the dental maturational pattern and tooth endostructural organization of Lagar Velho 1 are absent from extant populations and the Magdalenian specimen and are currently documented only among Neandertals.

Therefore, a simple Neandertal versus modern human dichotomy is inadequate to accommodate the morphostructural and developmental variation represented by Middle Paleolithic and earlier Upper Paleolithic populations. These data reinforce the complex nature of Neandertal-modern human similarities and differences, and document ongoing human evolution after the global establishment of modern human morphology.

…and continues with this from the introduction:

It was with the goal of assessing whether the dental developmental patterns and microstructure of these earlier modern humans contrasted with later modern humans, and possibly approached the condition seen in the Neandertals, that we anaanalyzed the remarkably complete dentition of the Lagar Velho 1 child (19). Discovered in Portugal in 1998, this fossil is the >90% complete skeleton of a child (4–5 years old on the basis of dental maturation and limb bone lengths) ritually buried in a recess in the back wall of a rock shelter, at the base of an ∼3-m thick Gravettian to Solutrean stratigraphic sequence. The 14C-dated components of the burial context concur in placing the burial ∼24.5 ka 14C BP (∼30,000 calendar years ago), some five millennia after the replacement/assimilation of the last Neandertal populations of Iberia (20, 21). Preserving 46 of the possible 48 teeth (from calcified germs to complete teeth), all except one upper P4 and one lower P4 (and the four yet-to-calcify M3s) (19), the Lagar Velho 1 dentition provides a unique opportunity to assess these odontological aspects.

The Gravettian/Solutrean boundary obviously occurred sometime between the start of the Gravettian c.28 kya and the start of the Solutrean, c.21 kya,and it’s interesting to note that the 4-5 year old child appears to have been given what is described as a ritual burial, presumably around 24/25kya, some 20,000 years after the earliest recorded evidence of AMH in Europe.

This would make it a contemporary of the Gorham’s Cave Neanderthals at Gibraltar, but older than those whose remains have been proposed as even later surviving Neanderthals at La Carihuela, as well as another even younger site at Esquilleu that has yet to be confirmed in north of Spain, in both of which instances, Neanderthals appear to have not mixed with the AMH population, but survived living the Neanderthal life along with their traditional Mousterian stone tools

Those three sites tell their own story – La Carihuela holds the promise of actual Neanderthal fossils, tentatively dated to 21.5 kya, whilst Gorham’s Cave at 24,5 kya and Esquilleu, maybe a similar age as La Carihuela, contain Mousterian stone tools, and coming right at the end of the known existence of the Neanderthals, appear strongly suggestive of a Neanderthal population that was far from fully integrated into that of the AMH, either by blood or technology, thus making the putative hybrid from Portugal an exception to the general rule.

Here’s a note regarding the complex results of the research:

With the exception again of the Ui1 limited to the relative enamel thickness, both the average (AET) and relative (RET) enamel thickness values (Methods) recorded for all of Lagar Vehlo 1’s teeth follow the EH estimates, systematically setting it apart from the Neandertals because of their lower values (Figs. S2 and S3). In this respect, notably for the two deciduous and permanent molars, the extant human-like pattern of enamel distribution displayed by this child’s dentition is also evinced by the comparative thickness cartographies (Fig. S4).

For all of the absolute and relative variables describing dental tissue proportions, except the EDJ surface area, the results shown by the Lagar Velho 1’s lower first permanent molar (LM1) conform to those from its deciduous Lc and Lm2; they closely resemble the extant human figures. In all three cases, the potential influence of dental wear is negligible or null (Table S5). It is noteworthy that the lower canine of Lagar Velho 1 is affected by localized enamel hypoplasia (29) (Fig. 1C and Fig. S1C). Accordingly, the values displayed by both Upper Paleolithic children for the percent of the crown volume that is dentine and pulp and for the relative enamel thickness (Table S3) should be further shifted closer to the extant human values.

As a point of interest, this paper follows on from another, Anterior Tooth Growth Periods in Neandertals Were Comparable to those of Modern Humans, for which this is the abstract, and the rest of the paper is freely accessible too.

Summarised by Alan Boyle at Cosmic Log, we see:

Researchers led by Priscilla Bayle of France’s Museum of Natural History used X-ray micro-tomography to create 3-D images of the child’s teeth. They found that the front teeth were delayed in their degree of formation, compared with the state of the teeth farther back on the jaw. The front teeth also had more dentin and pulp than the teeth of more recent humans, but less enamel.  These characteristics don’t fit the pattern seen in today’s human population, or even the pattern for 12,000-year-old human teeth. They come closer to fitting the pattern for Neanderthals, the researchers said.

The University of Bristol’s João Zilhão, who found the skeleton and is a co-author of the study, said in a news release that the tooth analysis joins a growing body of evidence “that shows these ‘early modern humans’ were ‘modern’ without being ‘fully modern.'”  The university said the report “raises controversial questions about how extensively Neanderthals and modern human groups of African descent interbred when they came into contact in Europe.”

However, the study itself stops short of directly addressing those questions. Instead, the researchers say their findings “reinforce the complex nature of Neanderthal-modern human similarities and differences, and document ongoing human evolution” even after the rise of modern humans. They suggest further studies of juvenile teeth, going back 100,000 to 200,000 years, could make a significant contribution to charting the human family tree.

Although the authors decline to declare that this represents clear evidence of AMH and Neanderthal interbreeding, it’s difficult to ascribe a meaningful alterntative, especially when we consider the post-cranial elements of the specimen, whose limb proportions conform more closely to the Neanderthal model. Although some researchers have tried to pass this off as being evidence for nothing more than a ‘chunky kid’, a holistic approach which takes in discrete elements from both cranial and post-cranial morphology, in my opinion conclusively points us in the direction of AMH and Neanderthal admixture.

Such consideration of the skeletal remains as a whole certainly helped clarify the debate surrounding H. floresiensis, aka the Hobbit from Flores, where debates which only considered the cranial features persuaded some that the specimen was a diseased modern. Reality, however begged to differ, and since the publication of detailed research, especially on the out-sized feet and peculiar wrists of the hobbit, it seems abundantly clear that whoever else she may have been, LB1 was no anatomically modern human.

In the case of the Lagar Velho child, I think the most interesting results to come will be when its entire genome has decoded, if and when that ever happens – whether that tells us conclusively if this was indeed a hybrid child remains to be seen, but assuming that research of this type is carried out, we should at least have several more details of the overall picture.

Although this paper is freely accessible, you might find it easier to find it in this comment by Martin Cagliani, author of  Mundo Neandertal, who has very kindly provided it – hat tip to Maju/Luis for the heads-up to that. A link for the supplementary material appears below, and is also well worth checking out.

Bristol University Press Release

Fate of the Neandertals – João Zilhão, Archaeology.org, July/August 2000

Learning to Love Neanderthals – Robert Kunzig, Discover Magazine, August 1999

References:

1.Dental maturational sequence and dental tissue proportions in the early Upper Paleolithic child from Abrigo do Lagar Velho, Portugal — PNAS by Priscilla Bayle, Roberto Macchiarelli, Erik Trinkaus, Cidália Duarte, Arnaud Mazurier and João Zilhão

Published online before print January 4, 2010, doi: 10.1073/pnas.0914202107

2.Download Supporting Information (PDF)

3. Anterior Tooth Growth Periods in Neandertals Were Comparable to those of Modern Humans – by Debbie Guatelli-Steinberg,*†‡ Donald J. Reid, Thomas A. Bishop, and Clark Spencer Larsen

Proc Natl Acad Sci U S A. 2005 October 4; 102(40): 14197–14202. Published online 2005 September 23. doi: 10.1073/pnas.0503108102.

4. No Evidence of Neandertal mtDNA Contribution to Early Modern Humans – Serre D, Langaney A, Chech M, Teschler-Nicola M, Paunovic M, et al. (2004) No Evidence of Neandertal mtDNA Contribution to Early Modern Humans. PLoS Biol 2(3): e57. doi:10.1371/journal.pbio.0020057

22 thoughts on “Abrigo do Lagar Velho Dental Study – Neanderthal Hybrid Debate Continues

  1. Pingback: Anthropology.net
  2. “Although the authors decline to declare that this represents clear evidence of AMH and Neanderthal interbreeding, it’s difficult to ascribe a meaningful alterntative, especially when we consider the post-cranial elements of the specimen, whose limb proportions conform more closely to the Neanderthal model. Although some researchers have tried to pass this off as being evidence for nothing more than a ‘chunky kid’, a holistic approach which takes in discrete elements from both cranial and post-cranial morphology, in my opinion conclusively points us in the direction of AMH and Neanderthal admixture”.

    I’ve accepted it as being a hybrid since I first read about it. What interests me far more is the psychology of why so many of us are so opposed to the idea that modern humans and Neanderthals were completely capable of forming hybrids. Why should it be such a problem for such people to even consider the possibility?

  3. First of all, a lot of people have learned the “biological species concept” just a little too well, I think. If Neandertals and “modern” humans are supposed to be two different species, they shouldn’t have been able to interbreed, right(a biological species is a population that mates, and has offspring that mate and have offspring, etc., etc.) So if Neandertals and “modern” humans could interbreed and produce fertile offspring(and what Trinkaus and Zilhaõ claim about Lagar Velho is, that the population that produced the child was a “mixed” one), then supposedly they would be the same species.

    Trouble is, evolution is kind of messy. Closely related species can and do interbreed. Wolves x coyotes; in fact all members of the genus Canis are capable of producing fertile offspring. This includes jackals x coyotes, artificially crossed in labaoratories, but wolves x coyotes have occurred naturally, and there are “wolves” around the Great Lakes area that have “coyote” genes. There are also “coyotes” in New England and SE Canada that have “wolf” genes, apparently. People seem able to accept this, if the organisms involved aren’t human!

    And then there’s the little problem of the “cartoonish” way Neandertals have often been portrayed: walking bent-kneed, shambling around, small-brained, stupid. Who would want to interbreed with that? This “image” has persisted for more than 100 years.

    Finally, there is, not too far below the surface, a “racial” component that a lot of people don’t want to recognize. If Neandertals were a “race” that was somehow “inferior” to us(and what better way to turn Neandertals into a “race” than to claim they were a “species”, at least for many people), then who would want to “sully” their genetic heritage with “Neandertal” genes.

    I don’t believe humans can nowadays be divided into biological subspecies, but 50,000 or 100,000 years ago, this may not have been true. Human populations were small and widely scattered, but they were also mobile. This created conditions where some small and scattered populations developed characteristics that would show up as genetically unique, and this is what seems to have happened with Neandertals, who also appear to have been especially small and especially widely-scattered. There is plenty of genetic evidence that appears to show this. However, since they, as well as “modern” humans were both mobile, it’s quite possible that some of them, at some times, actually met and mated, and “hybrid” populations developed. This may be what happened on the Iberian Peninsula. But for these exact same “racial” reasons, there is still, to this day, a lot of resistance to the idea that Neandertals and “moderns” whether two (sub)species or one, could mate with one another. Many people just don’t like the idea that there might be “Neandertal genes” lurking around in them — whatever those “Neandertal genes” might turn out to be.
    Anne G

    1. I agree with you. As a matter of fact, I think most Europeans or they descendants like me have some Neanderthal genes. It will be difficult to prove because, only three Neanderthals were analyzed. I wonder how Neanderthals that lived a few decades, prior to their “extinction” look like.

  4. I think you’re mostly correct. However I see another possibility. If humans are portrayed as being a suddenly ‘new’ species at some time in our evolution we can still believe that we are ‘special’. Even accommodate ‘specially created’ quite easily.

  5. This is an interesting comment:

    “Therefore, a simple Neandertal versus modern human dichotomy is inadequate to accommodate the morphostructural and developmental variation represented by Middle Paleolithic and earlier Upper Paleolithic populations. These data reinforce the complex nature of Neandertal-modern human similarities and differences, and document ongoing human evolution after the global establishment of modern human morphology”.

    I’m firmly convinced that humans are not the suddenly new ‘separate species’ of the popular imagination. The change from archaic to modern humans was nowhere near as sudden, or as clearly defined, as most of us would like to believe. Speciation is never ‘sudden’ anyway. Any new species has to ‘recruit’ members to the new species from the old. This can take time.

    The change from archaic to modern was reasonably prolonged, with genes, technology and culture crossing any insipient subspecies boundary. In fact I strongly suspect that this has been the situation since Homo erectus/habilis/Australopithecus was first able to escape from Africa.

    Human groups (often combinations of previously geographically distinct groups) with more effective culture or technology have periodically been able to expand their genes through already occupied territory. Mixture between incomers and residents is the usual situation but sometimes residents become outnumbered. At other times the residents adopt the incoming technology, and off they go in turn.

    The haplogroup distribution we see today is simply a product of those periodic expansions, and the gradual extinction of other haplogroups. No Australopithecus haplogroups survive today for example, but most would agree they are part of our ancestry.

    I’d go further and suggest that male and female haplogroups are remarkably independent. Particular Y-chromosomes are often associated with particular technology expansions and particular mtDNAs are associated with culture expansions. Culture expands more slowly than technology so mtDNAs are older. But Y-hap Adam (Y-hap pre-A) and mtEve (mtDNA pre-L0) need never have met, or even lived at the same time. That’s why mtEve’s line is older. And that’s true for Y-hap CF and mtDNAs M and N as well.

  6. Terry and Rosario:

    One of the reasons I’ve always been kind of — not suspicious, exactly, but cautious of — any sort of claims about the “suddenness” and “newness” of the “modern” human type, is that the suggestions or theories of how this new “species” arose is quite unlike the human behavior or any human societies I’ve ver heard of. I don’t doubt that the earliest manifestations of this new type did, in fact, arise in Africa and spread from there, for a variety of reasons. One is that, apparently in prehistoric times, Africa had(and to some extent, still does have) a larger population than anywhere else, and a larger variety of human types than anywhere else, with concomitant genetic variety. This probably made it easy enough for the “modern morph” to spread fairly quickly(also this “morph” may have been more “energy efficient and so people with at least some of these genes tended to be more likely to survive and reproduce). In order for the “morph” to spread, however, there had to be at least some admixture in some populations at some times. And I think this may be what happened. Human behaviors cover a wide range, both potentially “hostile” and potentially “friendly”, with plenty of “wiggle room” in between. Furthermore, it doesn’t appear that the behaviors of either Neandertals or “modern” humans were all that different, and the standards of what constituted a good mate were probably not the same as they are in 21st century Western cultures. So I think at some times and places, matings, even at a relatively low level, were quite possible. As for “Neandertal genes”, well since the Neandertal genome is probably 98 or 99% identical to the modern human one, and since some “moderns” coexisted in time and in place with some Neandertals, there probably wasn’t any barrier, other than “cultural” to such matings. And under some circumstances, such “cultural” barriers were probably fairly weak. Of course even then, the populations involved were relatively small, and could easily have been “swamped” by later agriculturalists, but even so, some early European populations were probably “mixed”.
    Anne G

  7. Terry and Rosario:

    I think you are both right. While the evidence that the modern “morph” originat<ed in Africa seems rather overwhelming, it isn't really all that surprising, if you consider that, most probably, prehistoric Africa had more people, and more types of people, than anywhere else at the time. And it did nothing to prevent mixture, once some members of this group wandered away from Africa in search of whatever they were searching for. There also seems to be a good deal of evidence that behaviors of all members of the genus Homo were sufficiently similar that mating was most likely quite possible. By the time Neandertal and "modern" populations were coexisting in various parts or Eurasia, this was most likely true, whether one considers them subspecies of H.sapiens or two separate species. The differences between the two populations were (probably) more likely "cultural" than anything else, and while cultural differences of various kinds can be barriers to mating, barriers of this kind can be relatively weak. So I think some populations of early Europeans were probably "mixtures", though they probably were later "swamped" by incoming agriculturalists from other places, which may be one reason you don't find any "Neandertal genes" in today's European populations.

  8. terryt:

    I’m not really surprised. Lots of people are pretty resistant to any information which might change their viewpoint at all. It’s called “cognitive consistency”.
    Anne G

  9. Anne, Terry et al

    re ‘cognitive consistency’

    Having just watched the first episode of The http://www.pbs.org/wnet/humanspark/episodes/program-one-becoming-us/video-full-episode/395/ on the PBS site, I was amazed at the mental constipation on display throughout this inept presentation, which I think goes a long way to explaining the current impasse regarding the interbreeding debate .

    Time and again we see the anthro/archaeo TV elite telling us that Neanderthals lacked innovation, any notion of symbolism, creativity etc, pointing out supposed behavioural differences that in many cases and upon closer examination, simply fail to materialise, such as palaeo-diet variability, technological know-how and personal adornment, amongst others.

    Same old faces, peddling the same old twaddle in what will one day probably become known as the Lower Doculithic, the exponents of which will eventually become extinct due their lack of wider research and balanced presentation, pushed over the brink by an over-reliance on low production values.

    Where were people like Prof. Chris Stringer to add some counterweight to the many ludicrous assertions made throughout, or indeed comment from any number of other researchers whose work has clearly shown aspects of ‘modernity’ amongst the derided archaic humans who actually laid all the cognitive groundwork – language being a particular skill-set whose origins clearly date back long before AMH?

    My point being is that if qualified archaeo/anthros are allowed to appear time and again in these documentaries, and spout rubbish similar to that as in The Human Spark, with barely a hint of meaningful question or argument, how can anyone possibly expect there to be reasoned opinion amongst the viewing population to whom this sort of tripe is routinely spoon-fed?

    This is the sort of documentary nightmare that I’ve been complaining about for years – what might have been acceptable in the 80s or 90s due to a comparative lack of research, results and data, has no place here in 2010, or whenever Hum.Spk. was made – there’s no excuse for this type of shoddiness, and the sooner we get a new generation of enlightened researchers to represent and portray the human story, so much the better for us all.

    The last 10 minutes however were much more interesting, and would have made an ideal start for a greatly more revealing documentary on the Lower and Middle Palaeolithic, which instead of trying to find spurious differences between ourselves and ancestors, would concentrate instead on the many similarities we share – it’s too bad that commercial considerations mean it’ll probably never be made.

    So no, it doesn’t surprise me at all that people have difficulty embracing the concept of AMH and Neanderthals interbreeding – let alone other archaic species of humans, and other members of the animal kingdom at large doing the same thing – as long as people are determined to ask the wrong questions by looking only for differences to explain fallacies and contradictions, this debate will simmer on for a while yet.

  10. Tim:

    While Dr. Stringer has modified his views on Neandertals — somewhat — in the years since I was first “introduced” to him via a Nova
    documentary I saw some years ago, about the rise of “modern” humans, he still tends to think they of Neandertals as being “different” although he appears to now concede that these “differences” may have been far subtler than he was originally willing to believe. So I, personally, do not think he would have been the best addition to The Human Spark as far as “counterweighting” all this silly stuff about how “dumb” Neandertals were supposed to have been. There are, however, worse people who could have appeared there. I didn’t see the show, so I don’t know who they put on. But even in sober academic journals, you see this kind of “Neandertals were dumb and we had nothing to do with them” stuff, and the authors of these are themselves paleoanthropologists and prehistoric archaeologists. After that, a lot of this kind of “thinking” gets filtered onto “documentaries like The Human Spark, and from there, this is where people get the idea that calling someone a “Neanderthal” means they are regressive, dumb, backward-looking, conservative, etc. Which, the more I look at it, the more it seems to be an insult to Neandertals. Incidentally, I’m writing some “romantic science fiction” set in medieval England, that does everything can to “bust” these kinds of stereotypes.
    Anne G

    1. Anne:

      I mentioned Stringer because he has at least altered his 80s stance regarding Neanderthals, whereas too many of the people in the Human Spark have stuck rigidly to their ‘stoopid caveman’ guns in spite of continual emerging evidence to the contrary.

      At one point in the Human Spark, there was some conjecture as to how far back in time – 80-100 kya for example, you could take a human, educate them in the modern world and make them eligible for employment. If we did that to the Neanderthals, they’d go through Law School and then spend their entire working lives suing us for defamation of character.

      Good luck with the book.

  11. “as long as people are determined to ask the wrong questions by looking only for differences to explain fallacies and contradictions, this debate will simmer on for a while yet”.

    That’s very eloquently put Tim. Most of us seem determined to put as much distance as possible between us and the rest of nature.

  12. Thanks Terry – your comment reminds me of an old Simpsons cartoon in which the caption ‘Man vs. Nature – the Road to Victory’ appeared – can’t recall the context though.

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