Nature’s “Peopling the Planet” Issue

03 Thursday May 2012

Nature has published a special issue titled “Peopling the Planet.” Most articles are open access and provide nice introductions to past and current debates. This article by Andrew Curry covers the peopling of the Americas and the Clovis controversy, this piece by Tim Appenzeller discusses migrations out of Africa by modern humans and Toba debates, this article by Ewen Callaway covers the radiocarbon dating problem in Europe and how it is affecting the old models, and this editorial properly chastises some American archaeologists for the shameful handling of the Clovis debates. For some odd reason, Chris Stringer’s piece on what makes a modern human is behind a paywall. There is also a podcast covering a mix of all these topics:

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Hominin Meat on Allopatric Speciation Bones

07 Saturday Apr 2012

It is a curious fact that one of the more powerful mechanisms for explaining allopatric speciation — that climate change fragments previously continuous ranges into isolated refuges and splinters populations — pre-dates the publication of Darwin’s Origin. In 1846, naturalist Edward Forbes proposed that climate change during the Pleistocene accounted for the curious distribution of plant species in Europe. Darwin independently came to similar conclusions but never used these concepts to account for speciation.

This was left to Ernst Mayr, who announced in Systematics and the Origin of Species (1942) that new species develop “if a population which has become geographically isolated from its parental species acquires during this period of isolation characters which promote or guarantee reproductive isolation when the external barriers break down.” Mayr put empirical flesh on these theoretical bones by studying bird and fish speciation due to climatic change and geographic refugia. In a recent review published in Science, J.R. Stewart and Chris Stringer have done the same for hominins.

The article, “Human Evolution Out of Africa: The Role of Refugia and Climate Change,” is timely in several ways. Recent discoveries of apparently isolated and enigmatic hominins, such as Homo floresiensis, Denisovans, and Red Deer Cave people, suggest long-term geographic isolation of hominins who were spread thinly across the vast landscapes of Eurasia. While the usual explanation for isolation centers on geographic barriers, this is not entirely satisfactory. The widespread, albeit sparse, distribution of hominins in Eurasia speaks to their ability to surmount such barriers. If hominins could disperse so widely, there must be some other or supplemental explanation for the apparent isolation.

Were the migratory founding populations small and isolated from the start? Did they just wander off from neighboring groups, never to have contact again? Or did climate change fragment previously contiguous ranges, resulting in incremental isolation? Stewart and Stringer argue for the latter. As we enter the Anthropocene epoch of accelerated climate change, the argument resonates.

The refugia theory is elegantly simple. During interglacials, when climate warms and resources are more abundant, populations expand. Expanding populations often maintain a contiguous wave of advance which allows for gene flow between neighboring groups. During glacials, when climate cools and resources are less abundant, populations contract. Contracting populations sometimes lose contact with neighboring groups and become genetically isolated. This isolation, in turn, can lead to evolutionary change through drift or selection, depending on local conditions. Differences can become reinforced.

An excellent and easy example of this comes from Europe, which owing to geographic peculiarities, lends itself to this process. Populations expanding from the south may advance along a continuous front. But as they retreat from the north, a previously conjoined population may splinter, with one group isolated on the Iberian peninsula and another on the Italian. If glacials are of sufficient duration and severity, the result may be protracted isolation and perhaps even speciation.

Stewart and Stringer propose that several otherwise enigmatic features of hominin morphology and archaeology can be explained through these processes. Their list includes: the divergence of Homo heidelbergensis into Neanderthals and Homo sapiens, the European Neanderthal extinction, the puzzling modern human occupation of the Levant followed by its abandonment and re-occupation by Neanderthals, the modern human occupation of northern Europe and eventual abandonment ~26,000 years ago, and the disappearance of the Gravettian stone tool industry ~23,000 years ago followed by an archaeological gap of 8,000 years.

In answering the question “how did the evolution of archaic out-of-Africa humans take place,” the authors rely on refugia:

When a lineage adopts a new refugial area and survives for a number of Milankovitch cycles, expanding from and contracting into that new refugium instead of its original refugium, it is destined to evolve into a distinct population. Given enough time in isolation, it will become a new species. Because a new refugium is unlikely to have the same flora, fauna, and ecology as the lineage’s original refugium, it exerts selective pressure to adapt and diverge.

Therefore, when the initial expansion of archaic Homo out of Africa during an interglacial eventually suffered range contraction in the face of climatic deterioration, it was either going to go extinct locally or, because it was sufficiently broadly adapted, survive in an out-of-Africa refugium. It may well be that a broadly adapted taxon such as Homo was particularly well disposed to dispersals and eventual differentiation….Thus, the adoption of a new refugium by an expanded part of a population is the mechanism that often leads to phylogenetic speciation within continents.

If this is what happened (the devil is always in correlating the climatic details with morphological evidence or genetic data), it could explain mixed feature fossils. When refugia hominins met during times of range expansion, they did what modern humans seem quite fond of doing: mix up the mosaic.

– Posted by Cris

References:

Stewart, J., & Stringer, C. (2012). Human Evolution Out of Africa: The Role of Refugia and Climate Change Science, 335 (6074), 1317-1321 DOI: 10.1126/science.1215627

Mayr, E., & O’Hara, R. (1986). The Biogeographic Evidence Supporting the Pleistocene Forest Refuge Hypothesis Evolution, 40 (1) DOI: 10.2307/2408603

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Death of Indonesian Forests-Orangutans

23 Friday Mar 2012

This is a stunning and haunting video of the disappearing Indonesian forests, as seen through the eyes of a dying orangutan. The sound is brilliant. By filmmaker Patrick Rouxel and courtesy of Al Jazeera English:

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Science Integrators

21 Wednesday Mar 2012

Andrew Moore, editor in chief of BioEssays, recently published a piece that makes so much sense it will probably never happen. He argues that science suffers from data overload and that some scientists should be specially trained not to produce data but to analyze and synthesize data. Science integrators, as he calls them, would generate work beneficial to science insiders and outsiders. Unless graduate students can self fund their studies and eschew traditional pressures to specialize and produce data, what Moore proposes probably isn’t possible. But it’s a great idea that should be taken seriously:

I have a vision of a future in which scientists who think more about others’ results than producing their own are valued just as much…

“I think you’ve probably done enough reading now; you should start producing some results.” The PI smiled at the neophyte, who dutifully closed her laptop and reached for her lab notebook. And so the rampant pathogen Dataproducus compulsivans claimed another victim. The infection had spread to the whole group now, and yet some strongholds of resistance could still be identified in the larger institute. In a laboratory just down the corridor, there was a scientist who, at a recent conference, had unashamedly announced during his talk that he “[didn't] produce any data at all”, but rather “[did] research entirely in the published literature and existing datasets”. And yet he wasn’t a bioinformatician; and he wasn’t part of a dedicated data analysis service either. Rather one could call him a “professional integrator”: someone who gains higher level insights by critically analysing and integrating the discrete findings of others to create a new model that is more than the sum of its parts. And these days such a person – particularly if young – raises eyebrows. Why? Because our culture of science funding so overwhelmingly demands primary results, which are easily measured; to start a career that doesn’t do service to that maxim could be regarded as suicidal.

Part of the problem is that a laboratory’s output is not necessarily measured in intellectual advances, but in advances in quantities of new basic results that can be published. Primary results are crucial to science, and sometimes they do represent major intellectual advances. Furthermore, infection by Dataproducus compulsivans is necessary in a proportion of the population, otherwise there would be no results for professional integrators to work on. But which science funders specifically support endeavours based primarily on thought, rather than a constant stream of primary results? One could observe that thought is cheap compared with reagents and equipment in many fields. However, in other areas, e.g. genome sequencing, the lure of massive amounts of cheap data probably still distracts funders from the task of integrating them with other fields; beyond bioinformatic analysis, truly transdisciplinary thinking is needed here.

The benefits to science of professional integrators are enormous in my opinion – particularly if one considers science a creative profession requiring dispassionate analysis. The lack of “ownership” when considering numerous research papers in a given area is a real benefit for the professional integrator: she/he can weigh papers for and against a particular thesis with greater objectivity. A professional integrator will likely identify studies that are wrong, with minimal personal bias: as a larger picture of a biological phenomenon – a “synthesis” – forms, the inconsistencies in certain areas of the field are revealed. Moreover, an excellent synthesis almost always suggests new experiments. That observation addresses the perception that contemporary science is driven too much by data-collection and too little by hypotheses. Today, biological research produces orders of magnitude more primary results than secondary, synthetic insights, compared with the era in which Crick, Watson et al. thrived.

Hence I seriously propose professionally recognising integrators, starting with training in crossdisciplinary understanding, critical analysis and creativity, to name a few. Some scientists-in-the-making are naturals at these; others lean toward the “dryer” side of research. How can we culture them? I envision a new course at universities called “Synthetic Life Science”, as subsidiary study, and – for specialists – as a major or specialisation. Students would practise generally useful skills such as literature analysis and integration of concepts – competencies that are presently rather left to chance.

The problem starts early: as undergraduates, students learn the foundations of the subject; they then passage to learning how to do research – the emphasis being on generating results. Why the overwhelming preoccupation with generating more results? Aren’t there enough being produced? Arguably there are so many results around that we need more dedicated people who explicitly don’t produce new results, but rather distill out higher level insights. Naturals at this kind of science can also be spotted in the lab: supervisors should be mindful not to automatically denigrate diffuse interest or lack of single-mindedness: perhaps they are the signs of an “integrator”. And an “integrator” is every bit as much a scientist as a “producer”.

While there may come a time when Moore’s final sentence proves to be true, integrators today aren’t often considered members of the scientific club.

– Posted by Cris

Reference:

Moore, Andrew. (2012). Have we produced enough results yet, sir? BioEssays, 34 (3), 163-163 DOI: 10.1002/bies.201290005

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Red Deer Cave People — A New “Species” from China?

15 Thursday Mar 2012

Only those living in a cave could have missed yesterday’s announcement of a possible new human species, the “Red Deer Cave people,” who lived in China some 12,000 years ago. We shouldn’t be surprised to find different looking kinds of humans that are so recent. Neanderthals as a distinct species persisted until perhaps 28,000 years ago, and Homo floresiensis or “the Hobbit” until around 13,000 years ago. With DNA evidence showing that Neanderthals and Denisovans (~40,000 years) mixed with modern humans coming out of Africa, the picture we are getting is one of evolutionary complexity. The days of ancestral line drawing, with one typological species begetting another typological species, are over.

It is now clear that when co-existing groups of hominins encountered one another, they sometimes interbred. When hybridization occurs, we sometimes get odd looking fossils that don’t quite fit one specific type or another. What we are seeing is recursive evolution among populations: this hominin group here sometimes bred with this hominin group there. The result? Lots of human variation through time and across space. And fossils that are mosaic, exhibiting both archaic and modern features.

Viewed from a population perspective, identifying these new and idiosyncratic fossils from China as a new “species” seems a bit beside the point. They are recent hominins, clearly Homo, and may be some mix of erectus, neanderthalensis, denisovan, and sapiens. If genetic material can be recovered, we will get a better sense for this. In the meantime, let’s look at the fossils and the paper, which was published open access in PLoS.

This skull just looks odd, doesn’t it? You don’t need to be a morphologist to note some unusual features. The zygomatics (i.e., cheek bones beneath the eyes) are relatively thick and angled, a combination which gives the entire skull a Darth Vader-ish look. This is evident in comparison with modern humans:

Now let’s compare to a Neanderthal, the famous La Chapelle-aux-Saints:

Visual impressions aside, the paper provides detailed anatomical descriptions, measurements, and statistical comparisons with other hominins. Some features show affinities with modern humans whereas others show affinities with archaic humans. It’s a composite that could be consistent with admixture.

There are several interesting things in the paper that aren’t being reported or discussed in the press. The first I noticed was that dating could be an issue. These fossils were recovered years ago without tight archaeological controls. At one of the two sites, the authors were able to identify the sediments from which some fossils were removed and dated those. The fossils from the other site were encased in a block, and the authors used materials from the block itself for dating: “During preparation we recovered a thin flowstone adhering to the surface of the vault of the partial LL 1 skeleton, while charcoal fragments were collected from sediment within its endocranial cavity.” The potential problem here is that the covering flowstone and internal sediments (which contained the carbon datable charcoal) could be younger than the cranium. Unfortunately, there is no bone collagen that could be directly dated.

This comment on a skull cap or calotte caught my attention: “Evidently the specimen lost its base and facial skeleton owing to anthropogenic alteration, with cut-marks seen along the walls of the vault and on the zygomatic process.” This is a polite way of saying that the skull cap was processed by humans. There are two possibilities here: cannibalism or funerary.

For now the fossils are being called the “Red Deer Cave” people. This gives the impression there was a single cave when in fact the fossils came from two sites that are 300 km or 185 miles apart. Because the fossils show similar features and have similar dates, the authors have concluded they belonged to a single population. This sounds like a good null hypothesis.

According to numerous press reports, the fossils were found in association with various tools and fauna. These are not described in the paper so analysis will have to wait. Ideally, the tools, flora, and fauna will assist in the identification of these people and tell us what they were doing.

So who are these people and where are they from? The authors propose several alternatives:

The remains from Longlin and Maludong could represent very robust individuals within a previously unknown Epipalaeolithic population in southwest China. We consider this to be an unsatisfactory explanation because of the presence of several apparently unique features combined with an unusual mixture of modern and archaic features is seen in several specimens and spans multiple developmental-functional complexes (as noted above)….

In our opinion, there are more plausible explanations. One possibility is that the Longlin and Maludong remains represent a late surviving archaic population….Another possible explanation is that the unusual morphology of the Longlin and Maludong remains results from the retention of a large number of ancestral polymorphisms in a population of H. sapiens….The morphology documented at Longlin and Maludong might be interpreted as consistent with this hypothesis, the Chinese remains perhaps sampling a previously unknown human population (or migration?) that may not have contributed genetically to recent East Asians.

At this preliminary juncture, all the hypotheses are in play. Three labs are attempting to extract DNA which would allow for a test of the latter hypothesis. Pending DNA and the publication of additional details about these sites and others that might be in the area, we won’t know.

What we do know is that human evolution has been wonderfully varied, and we shouldn’t be surprised if any of these hypotheses prove correct. China is massively underexplored and promises to hold more surprises for the fossil future.

– Posted by Cris

Reference:

Curnoe, D., Xueping, J., Herries, A., Kanning, B., Taçon, P., Zhende, B., Fink, D., Yunsheng, Z., Hellstrom, J., Yun, L., Cassis, G., Bing, S., Wroe, S., Shi, H., Parr, W., Shengmin, H., & Rogers, N. (2012). Human Remains from the Pleistocene-Holocene Transition of Southwest China Suggest a Complex Evolutionary History for East Asians PLoS ONE, 7 (3) DOI: 10.1371/journal.pone.0031918

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New Evidence for Neanderthal Symbolism?

09 Friday Mar 2012

Two days ago my twitter stream lit up with the exciting news that Neanderthals were using symbols 90,000 years ago. I followed the tweets to this article published in PLoS on March 5: “Presumed Symbolic Use of Diurnal Raptors by Neanderthals.” If correct, this would be big news. It would mean not only that Neanderthals were capable of symbolic thought (a contested issue), but also that the evidence for this pre-dates the 77,000 year old incised ochre from Blombos Cave. The Blombos ochre is the leading candidate for the earliest symbolic thought in presumably modern humans, though this too is a contested issue.

What was found and is it evidence of symbolic behavior? At the first site, Combe-Grenal (~90 kya), there is a single talon from a golden eagle. At the second site, Les Fieux (~60-40 kya), there are two talons from a white-tailed eagle. On all three talons, there are incisions or cut-marks made by stone tools. Here are the photos:

As is evident, the talons are not perforated in a manner which would suggest they were worn. The cut-marks don’t appear deep enough for stringing or hanging. The talons were not found in burial contexts.

After describing and contextualizing the finds, the authors begin their discussion by stating:

Because claws are inedible, the specimens presented here are not compatible with human consumption. This means that the tool-marked terminal phalanges found at Combe-Grenal, Les Fieux, Pech de l’Azé IV, and Grotta di Fumane were likely used as tools and/or as items of symbolic expression.

From the premise that eagle claws aren’t edible, the authors draw the reasonable conclusion that the talons were being used or curated for some other reason: either as tools or symbols. The more parsimonious conclusion would be that they were being used as tools.

I’m not an experimental archaeologist but can conjure many possible tool uses for sharp eagle talons, ranging from awls to knives. Unfortunately, the authors don’t discuss possible tool usage or explain why talon tool use isn’t likely. Instead, they focus exclusively on the possibility that these are symbols.

They base their symbolic argument on the rarity of cut-marked talons at these sites, and the over-representation of eagles compared to other birds: “Although the sample size is small, the fact that all the terminal phalanges that show cutmarks are from eagles argues against their utilization in strictly non-symbolic contexts.” This is underwhelming.

There are many possibilities here. It is presumably difficult to catch adult raptors, which would explain their rarity in the assemblages. When they are caught, they were probably eaten and the cut-marks could be byproducts of consumption. After being eaten, the talons might have been removed because they are useful tools. The sharp points of sturdy talons can serve as punches or slicers.

These possibilities need to be seriously examined before claiming that these were symbols and might have been ornaments. While the authors suggest the latter as a possibility, the cut-marks don’t suggest ornamental use. If the talons had been perforated for stringing or beading, it would be a different story and possibly symbolic.

Despite the article’s title and the press it generated, these talons are not “presumptively” symbolic.

– Posted by Cris

Reference:

Morin, E., & Laroulandie, V. (2012). Presumed Symbolic Use of Diurnal Raptors by Neanderthals PLoS ONE, 7 (3) DOI: 10.1371/journal.pone.0032856

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Ancient History of Graffiti

08 Thursday Mar 2012

What exactly is “graffiti”? The answer may seem obvious and easy, but only if viewed from the perspective of a city official or property owner. Considered broadly and historically, graffiti can be much more and have different meanings. My question was prompted by the announcement that scholars have published the first comprehensive collection of near-eastern “graffiti” dating from the time of Alexander (4th century BCE) to the rise of Islam (7th century BCE):

History is often shaped by the stories of kings and religious and military leaders, and much of what we know about the past derives from official sources like military records and governmental decrees. Now an international project is gaining invaluable insights into the history of ancient Israel through the collection and analysis of inscriptions — pieces of common writing that include anything from a single word to a love poem, epitaph, declaration, or question about faith, and everything in between that does not appear in a book or on a coin.

Graffiti, which comprise a significant amount of the collected inscriptions, are a common phenomenon throughout the ancient world. Famously, the walls of the city of Pompeii were covered with graffiti, including advertisements, poetry, and lewd sketches. In ancient Israel, people also left behind small traces of their lives — although discussion of belief systems, personal appeals to God, and hopes for the future are more prevalent than the sexual innuendo that adorns the walls of Pompeii.

As is apparent, graffiti is not just a modern phenomenon. It is ancient. Indeed, I suspect it is much older than classical antiquity and that scholars who puzzle over the meaning of Paleolithic markings may sometimes be looking at the earliest graffiti.

The announcement of this project had another salutary effect; it reminded me of the classic graffiti scene from Monty Python’s Life of Brian:

– Posted by Cris

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Ochres and Ends

04 Sunday Mar 2012

Old Incised Ochre

One of the more famous rocks in the world comes from Blombos Cave in South Africa. It is a piece of incised ochre which is about 75,000 years old.

Some argue that it represents the ability to think symbolically. Others aren’t so sure and suggest the incisions are more like doodles. A recently discovered piece of ochre is even older, about 100,00 years old, and it too has been incised. The question is why. These incisions might be the byproducts of other activities or intentions.

Anumerical Languages and Math

Anthropologists have long known that some languages don’t have words for numbers. Such languages are anumerical. The Sapir-Whorf hypothesis, which posits that language conditions and constrains thought, would lead to the prediction that anumerical speakers are unable to do math. This study of anumerical Amazonian people confirms that prediction.

The New Phrenology

Phrenology has long been ridiculed as pseudo-science, and in its mass popular forms this was for good reason. But there was a scientific aspect to phrenology, for which its founder Franz Joseph Gall (1758-1828) deserves credit. This recent study links the structure of the lateral orbitofrontal cortex to measures of social conformity. It confirms Gall’s basic hypothesis that differences in brain structure are related to differences in behaviors.

Darwin’s Rock Pigeons

As everyone who has read the Origin of Species knows, Darwin was fascinated by the selective breeding of domesticated rock pigeons. The pigeons play an important role in the Origin, with Darwin using them as analogues for the selection that occurs naturally in feral or wild populations. That makes this recent study, “Divergence, Convergence, and the Ancestry of Feral Populations in the Domestic Rock Pigeon,” all the more exciting. It’s nice to see pigeons still playing an important role in evolutionary biology.

Early Human Archaeology in South Africa

This Nature story on Chris Henshilwood’s work nicely captures the embarrassment of early human archaeological riches along the South African coasts. From 100,000-60,000 years ago, humans in this area were doing some things that anticipate the “cultural explosion” associated with the European Upper Paleolithic 45,000 years ago. The story includes this interesting biography:

Outside the cave, a cool November breeze scours the steep slope to the shore, which Henshilwood has known since he was a child. His grandfather bought this land on the Southern Cape as a fishing retreat in 1961 and Henshilwood spent his holidays searching the hills and caves for ancient artefacts.

Those experiences served him well in 1985, when, out of sheer boredom in his mid-thirties, he decided to leave the family department-store business and enrol in an archaeology course at the University of Cape Town. In 1991, as a PhD student on a scholarship at the University of Cambridge, UK, he returned to Blombos in search of the same kind of artefacts that he had found as a child. What he discovered was much more significant and far older: a series of bone tools and double-sided stone points that were clearly tied to the enigmatic Still Bay period.

– Posted by Cris

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First Americans — From Europe?

01 Thursday Mar 2012

It is generally accepted that the first Americans were Asians who either walked or boated to the new continent in waves beginning perhaps 18,000 years ago. Genetics certainly support this view. But there is an alternative, known as the Solutrean Hypothesis, which contends that the first Americans came from Europe rather than Asia. The argument is not without intriguing evidence but is an extreme minority view.

Its primary advocates, the Smithsonian’s Dennis Stanford and Exeter professor Bruce Bradley, have mustered their evidence and arguments in a new book, Across Atlantic Ice: The Origin of America’s Clovis Culture. The book has gotten a boost from this article, which makes some extraordinary claims:

New archaeological evidence suggests that America was first discovered by Stone Age people from Europe – 10,000 years before the Siberian-originating ancestors of the American Indians set foot in the New World.

A remarkable series of several dozen European-style stone tools, dating back between 19,000 and 26,000 years, have been discovered at six locations along the US east coast. Three of the sites are on the Delmarva Peninsular in Maryland, discovered by archaeologist Dr Darrin Lowery of the University of Delaware. One is in Pennsylvania and another in Virginia. A sixth was discovered by scallop-dredging fishermen on the seabed 60 miles from the Virginian coast on what, in prehistoric times, would have been dry land.

The new discoveries are among the most important archaeological breakthroughs for several decades – and are set to add substantially to our understanding of humanity’s spread around the globe.

I’ve searched for recent journal articles authored by Stanford, Bradley, and/or Lowrey but am not able to find anything. With discoveries such as this, publication is obviously important. Is anyone aware of articles on these new finds?

– Posted by Cris

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This Old Hut (Gimme Shelter)

24 Friday Feb 2012

Humans have been seeking shelter for a long time. While caves sometimes provided it, the idea that caves were the dominant form of ancient house is probably mistaken. Caves are like beacons to archaeologists. Relatively easy to find, they are systematically searched for signs of old occupation. If a cave was used by humans in the past, there is a decent chance of finding evidence of it. The same sheltering effects sought by humans work in favor of preservation. Because caves often contain remains of bygone days, we are left with the impression that the ancients preferred to live in them. In some places this may have been true but in others it is unlikely. Caves can be cold, damp, dark places and are not always available. Even those ideally located near abundance would eventually become stale and resources would become harder to find. When game moves, so must people.

Out in the open, a different sort of shelter was needed. Depending on what was available locally, most shelters would have been built with branches, grasses, bark, and hides. When Europeans made contact with mobile foragers in the Americas, they noted the widespread use of wickiups, which were built in all shapes and sizes depending on needs. Smaller shelters were constructed while on the move and larger ones when in camp.

As you can see, wickiup-type shelters are temporary and insubstantial. Once abandoned, they deteriorate quickly and eventually disappear. For archaeologists, this means that the presence of shelters can only be inferred, often by the presence of cooking rings, butchered bones, and broken tools. Finding evidence of an actual shelter is extremely rare.

All this makes the 20,000 year old hunter-gatherer huts recently reported by Lisa Maher and colleagues in PLoS One extraordinary. The archaeologists obviously did not find huts, but features which they infer to be the remains of huts:

Structure 1 was exposed approximately 60 cm below modern surface in Area B. It is oval in plan, measuring 3.2 m by 2.2 m and consists of several distinct layers. The structure was placed into a shallow depression dug into the preceding occupation deposits. A thin (2–3 cm), compact, dark reddish-brown clayey deposit represents the former floor of the structure. It is overlain by an organic-rich, black layer (c. 5 cm thick) containing abundant charcoal fragments that represent the residue of in situ burning. Burning also reddened the structure’s former floor, making its deposits notably different in color and texture from the sediments surrounding the dwelling.

The almost sterile, orange sand covering the shell caches has only been found in association with the hut structures. It does not occur in any other archaeological context, nor does it appear naturally in the immediate vicinity of the site, indicating it would have to have been brought in, perhaps to cover the dwellings and their associated features. In addition, large stones are not found naturally in any on-site deposits, so their presence in the hut structure suggests intentional placement.

[W]e interpret the thin, burnt, charcoal-rich layer on top of the structure’s floor as the remnants of the hut’s former superstructure, which burned and collapsed onto the floor. Further examination of the macro- and micro-botanical remains taken from this layer is currently underway, but the types of charcoal documented in other contexts suggest it highly likely that this was probably constructed of locally-available vegetation.

Judging the issue by this narrative, it sounds like a wickiup-type shelter. In this instance, the pictures are (to the untrained eye) worth less than words:

All in all, this is an exceptional site that raises all manner of interesting questions about hunter-gatherers, mobility, sedentism, funerary, and symbolism. The article is open access and well worth a close read, as it addresses these and other issues.

In honor of huts and fine archaeological work, it seems right to cap this Friday with Mick, Bono, and Fergie singing for shelter:

– Posted by Cris

Reference:

Maher, L., Richter, T., Macdonald, D., Jones, M., Martin, L., & Stock, J. (2012). Twenty Thousand-Year-Old Huts at a Hunter-Gatherer Settlement in Eastern Jordan. PLoS ONE, 7 (2) DOI: 10.1371/journal.pone.0031447

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