Federico Solorzano and the Homo erectus brow ridge found in Mexico

Recently I was reading through an old copy of the Mammoth Trumpet (1) for a bit of entertainment and I came across a report on the 2^nd International Symposium “El Hombre Temprano en America” (Early Humans in the Americas) which was held in Mexico City 6-10^th September 2004. Amongst the interesting snippets of news was a reference to a mystery fossil that has always been close to my heart, namely the Solorzano Homo erectus brow ridge. It was only a snippet, so I reproduce it in full here:

“Frederico Solorzano (Centro INAH Guadalajara) discussed bone fossils collected from 1937 to 1996 from the margins of Lake Chapala in Jalisco. The resulting assemblage includes some 40 fragments of human bone. Noteworthy among these is a brow ridge fragment of a frontal bone that more closely resembles Homo erectus than anatomically modern humans. Solorzano’s paper caught the interest of an Associated Press reporter, who wrote a news article entitled “Debate over Human Origins in America”.

 

Naturally this piqued my interest, so I googled the title. Lo and behold on an extremely esoteric website (2) I found a transcript of the article with a picture. I have reproduced it below for any of those interested.

Solorzano holding the brow ridge.

Photo credit: source unknown (2)

Brow ridge - red box shows approximate size of Solorzano fossil
Photo credit: Adapted from Homo erectus, University of Michigan Museum of Natural History, Ann Arbor, Michigan

“For decades, Federico Solorzano has gathered old bones from the shores of Mexico’s largest lake - bones he found and bones he was brought, bones of beasts and bones of men. The longtime teacher of anthropology and paleontology was sifting through his collection one day when he noticed some that didn’t seem to fit: a mineral-darkened piece of brow ridge bone and a bit of jaw that didn’t match any modern skulls. But Solorzano found a perfect fit when he placed the brow against a model of the Old World’s Tautavel Man - member of a species, Homo erectus, that many believe was an ancestor of modern Homo sapiens. The catch: Homoerectus is believed to have died out 100,000 to 200,000 years ago - tens of thousands of years before men are believed to have reached the Americas.

And archaeologists have never found a trace of Homo erectus in the Americas. ‘‘Most people sort of just shook their heads and have been baffled by it,’’ said Robson Bonnichsen, director of the Center for the Study of the First Americans at Texas A&M University. ‘‘That doesn’t mean it’s not real. It just means there’s not any comparative evidence.’’ Solorzano’s find was described at a September conference here that drew academics from Europe and the Americas to discuss new research on early man in the Americas. That primitive brow ridge from Lake Chapala ‘‘is in a category by itself,’’ Bonnichsen said. It is so strange - and so out of context - that it has been largely ignored even as other discoveries are raising basic questions about the story of human beings in the Americas: when they arrived and where they came from.

 

Changing picture

Until recently, most U.S. archaeologists believed that the first Americans arrived about 13,500 years ago when a temporary land corridor opened across the Bering Strait. The migrant Clovis people, named for a site near Clovis, N.M., apparently hunted mammoths and other large animals, leaving scatterings of finely worked spear tips and other tools across North America and, some argue, South America. A sometimes vehement minority still holds to that ‘‘Clovis first’’ position. The evidence of what could have come before remains sparse, scattered and controversial. Archaeologists have proposed possible alternative routes to the Americas - across the Pacific from Asia or Australia, across the Atlantic from Europe or Africa - though most say a trip from northeast Asia is most likely, perhaps by people advancing along a frozen coast in small boats.

 

South American researchers say they have found numerous sites that are 10,000 to 15,000 years old and argue that Clovis people could not have migrated all the way to Tierra del Fuego, at the southern tip of South America, so soon after the ice-free corridor opened from Asia to Alaska.

 

Argentine archaeologist Laura Miotti agrees the settlers likely came from the north. But she and others say there are no Clovis-like finds in the part of Asia from which the migrants supposedly came, and they question why North American sites don’t appear to be older than those in South America.

 

The evidence for earlier human habitation in the Americas, however scanty, is tantalizing. It includes:

A possible handscraper splotched with blood more than 34,000 years ago at Monte Verde in Chile.

Possible stone tools at a site in Brazil that is 40,000 to 50,000 years old.

A not-yet-published report of human remains dated as much as 28,000 years old near Puebla in central Mexico.

 

Early dates questioned

Most crucially, a majority of archaeologists are convinced that a second site at Monte Verde dates to at least 14,000 years ago - about 500 years before the land bridge from Asia opened more than 9,000 miles to the north.

 

Yet the early dates are still often questioned.

 

A claim of 250,000-year-old human tools near Mexico’s Valsequillo reservoir was widely laughed at in the 1970s, though other researchers are once again working at that area.

Clovis-first advocates suggest that the early dates may reflect variations or errors in the still-developing technologies of dating old samples.

They say natural breakage could account for some of what look like early tools and that the dating of others was likely confused, as when streams, floods or human beings mix new material into old.

 

As for human remains, only two teeth in Brazil seem to have been directly dated to clearly pre-Clovis times.

 

‘‘If you are trying to break through a barrier that is well established, you need well documented, incontrovertible proof,’’ said archaeologist Stuart Fiedel, author of a textbook on early Americans and a proponent of the Clovis-first model.

 

Both sides say that new research on DNA and climate history supports their claims, or at least fails to undermine them.

 

Solorzano’s finds raise so many unanswerable questions that they have remained just a curiosity.

 

Solorzano, 83, is a respected researcher who has taught generations of university students in the city of Guadalajara. His home office holds a cabinet full of bones - some of them human - topped by 14 realistic models of hominid skulls.

 

He says the brow bone raises ‘‘many questions, one of them being its great and amazing resemblance to primitive hominid forms whose presence in the Americas has not been generally accepted.’’

 

The few other scientists who have analyzed the bones closely agree that they look human - not animal - and are very, very old.

 

‘‘They were definitely human,’’ said Joel Irish, a specialist in bioarchaeology at the University of Alaska, Fairbanks.

 

He suggested they could be from ‘‘a very primitive looking modern human,’’ but said they would be ‘‘very early.’’

 

Efforts to date the pieces using modern techniques so far have failed due to lack of surviving tissue.

 

Most frustrating for archaeologists, who are accustomed to fussing over the tiniest details, is that nobody knows quite where the bone came from or even when it was found. It was apparently picked up when drought exposed a large ring of the Chapala lake bed from 1947 to 1956.

 

Archaeologist Stanley Davis, then at Texas A&M, spent several seasons accompanying Solorzano on surveys of the region and said he located places he would like to investigate further.

 
‘‘It takes a lot of money. That’s the reason I’m not down there working right now,’’ he said by telephone.
 
Davis said other human bones in the same area that are about 6,000 to 7,000 years old lack the mineralized darkness of age found in the brow and jaw pieces.
 
Migration hot spot?

Davis said the Chapala area is interesting because the lake is very old and is a likely spot for coast-hopping migrants to come inland.

Yet relatively few people have investigated the area so far. Until recently, Mexican archaeologists tended to focus on the spectacular indigenous cultures of the Olmecs, Mayas, Aztecs and others that arose in the last 3,000 years or so.

Davis said the Chapala-area finds included 12 scattered skulls of a long-extinct horse species. All have been smashed between the eyes.

 

‘‘Either we have a herd of very stupid horses . . . or we have some other action responsible for their death. That action is probably human,’’ he said. He estimated the horses were likely 10,000 to 20,000 years old.

 

A cache of swamp-deer teeth included several that were grooved, apparently for use in a necklace, he said. A radio carbon test showed one was roughly 20,000 years old. ‘‘That tells us we may have something.’’”

Verdict: Homo erectus in the Americas not proved, the fossil however is an interesting anomaly, Chapala needs more study!

 

References

1. http://www.centerfirstamericans.com/mammoth/issues/Volume-20/vol20_num1.pdf

 
2. http://www.hotspotsz.com/search.php?q=erectus&offset=6&go=5

Being Human 2 - Is the newly discovered human variability in postprandial (postmeal) glycemic response genetically based and is it therefore similar to the genetically based Lactose Persistence found in Europeans?

I think we are all aware that when we eat, our body breaks down carbohydrates to glucose and therefore our blood sugar (glucose) level rises after eating. A really interesting paper about this came out in Cell in November (1). The paper is open access and can be found here. Here’s the summary:

 

“Elevated postprandial blood glucose levels constitute a global epidemic and a major risk factor for prediabetes and type II diabetes, but existing dietary methods for controlling them have limited efficacy. Here, we continuously monitored week-long glucose levels in an 800-person cohort, measured responses to 46,898 meals, and found high variability in the response to identical meals, suggesting that universal dietary recommendations may have limited utility. We devised a machine-learning algorithm that integrates blood parameters, dietary habits, anthropometrics, physical activity, and gut microbiota measured in this cohort and showed that it accurately predicts personalized postprandial glycemic response to real-life meals. We validated these predictions in an independent 100-person cohort. Finally, a blinded randomized controlled dietary intervention based on this algorithm resulted in significantly lower postprandial responses and consistent alterations to gut microbiota configuration. Together, our results suggest that personalized diets may successfully modify elevated postprandial blood glucose and its metabolic consequences.”

 

Image credit: Zeevi et. al. 2015 (1).

 

Not very interesting or informative is it? Nothing to interest those of us wading through the tsunami of data in the scientific literature and searching for meaning about the state of being human?

 

Well, I wouldn’t have hunted the paper down at all if it wasn’t for an interview I heard with Eran Elinav (one of the authors), on BBC Radio 4 (- I live in the UK), waxing lyrical about the HUGE variability the team had found in Postprandial Glycemic Response (PPGR) in humans. In particular he mentioned that humans had an unexpectedly massive range in rise of blood glucose concentration in response to standardised meals but ALSO to a range of foods including beer, ice cream, dark chocolate, bread and even sushi!

Basically he was saying that, when all outside factors are controlled for there was STILL an absolutely unexplainable difference in response to the same foods.

 

In their introduction the authors outline the problems that high postprandial glucose response (PPGR) can cause and the methods previously used to estimate it:

 

“Blood glucose levels are rapidly increasing in the population, as evident by the sharp incline in the prevalence of prediabetes and impaired glucose tolerance.. Prediabetes, characterized by chronically impaired blood glucose responses, is a significant risk factor for type II diabetes mellitus (TIIDM).. It is also linked to other manifestations, collectively termed the metabolic syndrome, including obesity, hypertension, non-alcoholic fatty liver disease, hypertriglyceridemia, and cardiovascular disease. Thus, maintaining normal blood glucose levels is considered critical for preventing and controlling the metabolic syndrome.

Dietary intake is a central determinant of blood glucose levels, and thus, in order to achieve normal glucose levels it is imperative to make food choices that induce normal postprandial (postmeal) glycemic responses. Postprandial hyperglycemia is an independent risk factor for the development of TIIDM, cardiovascular disease, and liver cirrhosis and is associated with obesity, and enhanced all-cause mortality in both TIIDM and cancer.

Despite their importance, no method exists for predicting PPGRs to food. The current practice is to use the meal carbohydrate content even though it is a poor predictor of the PPGR. Other methods aimed at estimating PPGRs are the glycemic index, which quantifies PPGR to consumption of a single tested food type, and the derived glycemic load. It thus has limited applicability in assessing the PPGR to real-life meals consisting of arbitrary food combinations and varying quantities, consumed at different times of the day and at different proximity to physical activity and other meals.”

 

Frankly I found this absolutely ASTOUNDING! Basically doctors have NO adequate tools for adequately assessing an individual patient’s response to food in the REAL world! It would seem, to me, that we have at present, little hope in dealing with this worldwide problem!

 

The current paper attempts to address these linked problems.

 

Here is how they collected their data:

 

“Each participant was connected to a continuous glucose monitor (CGM), which measures interstitial fluid glucose every 5 min for 7 full days (the ‘‘connection week’’), using subcutaneous sensors (Figure 1D). CGMs estimate blood glucose levels with high accuracy and previous studies found no significant differences between PPGRs extracted from CGMs and those obtained from either venous or capillary blood. We used blinded CGMs and thus participants were unaware of their CGM levels during the connection week. Together, we recorded over 1.5 million glucose measurements from 5,435 days. While connected to the CGM, participants were instructed to log their activities in real-time, including food intake, exercise and sleep, using a smartphone-adjusted website.”

 

Image credit: Zeevi et. al. 2015 (1).

 

Here is some of the detail on what they found:

 

“As expected, the PDP of carbohydrates (Figure 4A) shows that as the meal carbohydrate content increases, our algorithm predicts, on average, a higher PPGR. We term this relation, of higher predicted PPGR with increasing feature value, as non-beneficial (with respect to prediction), and the opposite relation, of lower predicted

PPGR with increasing feature value, as beneficial (also with respect to prediction; see PDP legend in Figure 4). However, since PDPs display the overall contribution of each feature across the entire cohort, we asked whether the relationship between carbohydrate amount and PPGRs varies across people. To this end, for each participant we computed the slope of the linear regression between the PPGR and carbohydrate amount of all his/her meals. As expected, this slope was positive for nearly all (95.1%) participants, reflective of higher PPGRs in meals richer in carbohydrates. However, the magnitude of this slope varies greatly across the cohort, with the PPGR of some people correlating well with the carbohydrate content (i.e., carbohydrates ‘‘sensitive’’) and that of others exhibiting equally high PPGRs but little relationship to the amount of carbohydrates (carbohydrate ‘‘insensitive’’; Figure 4B). This result suggests that carbohydrate sensitivity is also person specific.”

 

“The large interpersonal differences in PPGRs are also evident in that the type of meal that induced the highest PPGR differs across participants and that different participants might have opposite PPGRs to pairs of different standardized meals (Figures 2D and 2E).”

Here are some of their graphs:

 

 

 

Image credits: Zeevi et. al. 2015 (1).

 

Lastly the authors state that the gut Microbiome data (the microbe faunal composition of an individual’s digestive system) could be correlated with an individual’s PPGR. Essentially some gut bacteria are associated with risk factors for high PPGR. Proteobacteria and Enterobacteriaceae both exhibit positive associations with a few of the standardized meals PPGR (Figure 2H). These taxa have reported associations with poor glycemic control, and with components of the metabolic syndrome including obesity, insulin resistance, and impaired lipid profile. RAs of Actinobacteria are positively associated with the PPGR to both glucose and bread, which is intriguing since high levels of this phylum were reported to associate with a high-fat, low-fiber diet.

 

A good table showing the glycemic index for some foods is shown in the supplemental Information:

 

 Image credits: Zeevi et. al. 2015 (1).

 

Of particular note are all the carbohydrate containing foods from bread onwards. Bread, Greek pastries, wholemeal bread, rolls, and wholemeal rolls are all derived from wheat. Human exposure to processed wheat and its associated gluten is extremely recent and dating to the advent cereal growing in the Middle East ca. 10000 years ago. Other foods on this list include Potatoes, Rice and Cereal (in this case Cornflakes containing entirely maize flour). All these plants are also those which have entered human diets over same time-span.

 

Interestingly Persimmons from south china are also high in carbohydrates and soluble dietary fibre known as FODMAPs which have been implicated causing digestive issues (2).

 

Some speculations

I find it quite startling and also very suggestive that this variability in human response to carbohydrate is SO varied.

 

Many of the foods causing the greatest PPGR are foods that have entered human diets during an extremely recent evolutionary interval. Indeed the great proportion of evolutionary changes that have happened to make us humans (the HARs of our genome, see here) date to just after our ancestors split from chimpanzees.

 

Thus my question is are all humans as equally adapted to eating these grains/sources of carbohydrates and their processed derivatives? Indeed the authors note genetic factors as a likely source of PPGR in humans, in their introduction.

 

Therefore I find it extremely plausible that it is possible that some humans carry an allele regulating PPGR similar to that responsible for Lactose Persistence in Europeans.

 

 

References

1. Zeevi, D. et. al. 2015. Personalized Nutrition by Prediction of Glycemic Responses. Cell 163, 1079–1094, (November 19).

 

2. Kris Gunnars at Authority Nutrition. Retrieved from http://authoritynutrition.com/foods/persimmons/

 

Sulawesi stone tools - evidence of early boat use in Homo erectus?

A great paper on some really ancient lithics from south east Asia by Gerrit D. van den Bergh and colleagues came out this week (1). Here's the abstract:

Sulawesi is the largest and oldest island within Wallacea, a vast zone of oceanic islands separating continental Asia from the Pleistocene landmass of Australia and Papua (Sahul). By one million years ago an unknown hominin lineage had colonized Flores immediately to the south, and by about 50 thousand years ago, modern humans (Homo sapiens) had crossed to Sahul. On the basis of position, oceanic currents and biogeographical context, Sulawesi probably played a pivotal part in these dispersals. Uranium-series dating of speleothem deposits associated with rock art in the limestone karst region of Maros in southwest Sulawesi has revealed that humans were living on the island at least 40 thousand years ago. Here we report new excavations at Talepu in the Walanae Basin northeast of Maros, where in situ stone artefacts associated with fossil remains of megafauna (Bubalus sp., Stegodon and Celebochoerus) have been recovered from stratified deposits that accumulated from before 200 thousand years ago until about 100 thousand years ago. Our findings suggest that Sulawesi, like Flores, was host to a long-established population of archaic hominins, the ancestral origins and taxonomic status of which remain elusive.

Former project leader Michael Moorwood (deceased) examines the 110-198Ky old stone tools. Photo credit: Annamaria Talas.

This is an awesome discovery, and the dates largely rule out modern humans as the tools' creators. Therefore we are probably looking to Homo erectus as the most likely candidate or perhaps Homo floresiensis as the toolmaker.

 

Another point to note is that at the time the tools were made Sulawesi was still an island, as it is today. Therefore whoever made the tools must have arrived by boat. If the tools are 200000 years old this would be one of the earliest use of boats.

 

Mind you the lead author, van den Bergh  had a weird take on the arrival of humans on the island, as he told Science News (2):

“Personally, I think Homo erectus is the most likely candidate. Ancient H. erectus colonizers probably didn’t navigate the ocean in canoes or other vessels, instead, occasional tsunamis could have washed small numbers of H. erectus into the sea from Southeast Asia’s coast. Southerly currents would have pushed castaways floating on vegetation or debris to Sulawesi. Accidental journeys of that kind probably explain how extinct elephants and other animals, known from fossil remains discovered in the new excavations and on my previous expeditions, ended up on Sulawesi more than 200,000 years ago".

 

Oh COME on! The makers of the tools he found were capable of the skilful execution of complex manual tasks that required planning and intent. They came form a population that (presumably) lived by and off the ocean for many millennia. Therefore the development and use of boat technology makes logical sense for these humans (of whatever species they were).

 

Therefore, to hear scientists who have completed work like this, to such an extremely high standard, play down the achievements of equally intelligent, if ancient humans makes me extremely irritated.

 

Lastly humans using boats at this extremely early date, have profound implications for the peopling of not only Sahul but of the Americas.

References

1. Gerrit D. van den Bergh et. al. 2016. Earliest hominin occupation of Sulawesi, Indonesia. Nature 529, 208–211 (14 January 2016) doi:10.1038/nature16448
Abstract retrieved from: http://www.nature.com/nature/journal/v529/n7585/full/nature16448.html#extended-data

2. Article retrieved from:
https://www.sciencenews.org/article/ancient-stone-tools-raise-tantalizing-questions-over-who-colonized-Sulawesi

Additional reading
Some interesting comments on migration issues by Austin Whittall here.

Siberian Archaeology 2: Diring Yuriakh

The Diring Yuriakh site lies approximately 140km SSW of Yakutsk on the Lena River, on a point formed by its junction with its tributary, the Diring Yuriakh creek.

 

 

Diring Yuriakh location. Photo credit: Walters 1997 (1).

Original caption: Fig. 1. Map of eastern Russia showing the location of Diring Yuriakh.

 

Approaching the Diring Yuriakh site along the Lena River (3).

Photo credit: Courtesy of the Center for the Study of the First Americans.

The Diring Yuriakh site was discovered accidentally, in June 1982, by Russian geologists, led by O. V. Grinenko whilst they were excavating a geological test pit to show the Cenezoic deposits of the 90m Tustakhsk terrace of the Lena River to participants in the International Union for Quaternary Research, (INQUA) congress XI held in Moscow and came across human bones (2).

The human bones recovered were of late Neolithic date and proved to be from a series of burials or graveyard belonging to the Ymyiakhtakh culture as shown by an excavation carried out in October of the same year, by Yuri Mochanov.

 

Excavations at Diring, adapted from Mochanov 1993 (2)

Yuri Mochanov

Photo credit: Courtesy of the Center for the Study of the First Americans (3).

The history of the site discovery and subsequent excavations is recounted by Mochanov in his first English language publication on the site The Ancient Palaeolithic Site of Diring and the Problem of a Nontropical Origin for Humankind (2). Most of what follows is a summary of that paper:

 

“Near burial V at a depth of 60cm, a flint core, seven flint microblades and 14 small flint flakes were found in the second paleosol from the bottom.. and belong to the late Neolithic Diuktai culture.. in the lower paleosol a concentration of quartzite artifacts was found lying directly on top of the gravels. These included an anvil cobble, two cobble hammerstones, eight amorphous flakes and 92 pieces of debitage.. The concentration of quartzite artifacts was separated from the Diuktai finds by a layer of sterile sand 5-12cm thick. The absence of any kind of diagnostic tool prevented the clear establishment of a cultural-chronological relationship for the quartzite artifacts. In appearance they were unusual for the early cultures of the Yakutia (the region of the site). ..the flakes were obtained (from cores) by a nonsystematic method of splitting cobbles ..unlike the Diuktai flint artifacts, there were well-preserved traces aeolian abrasion on many of the quartzite artifacts ..Traces of abrasion were present not only on pebble cortex, but on the cleavage plane of the detached flakes and debitage as well. ..I have not in 20 years of work on archaeological sites of Northeast Asia, encountered either the technique of nonsystematic flaking of cobbles or wind-abraded stone artifacts. ..(previous) experiments in the flaking of cobbles and nodules of various stone and examination of various museum collections of stone tools permitted the following conclusion: the method of nonsystematic flaking (of cobbles and nodules) was characteristic only during the earliest stage of the Stone Age, when people had not yet mastered the techniques of removing flakes from specially prepared cores..”

 

Flaked Cobbles and Chopper (3).

Photo credits: Courtesy of the Center for the Study of the First Americans.

 

 

 

Core with flakes (above) and flakes refitted (below). (3).

Photo credit: Courtesy of the Center for the Study of the First Americans

In a roundabout manner Mochanov then brings up the technologically similar, simple nonsystematic breaking of stones found in the Oldowan and Acheulian lithic complexes of approximately 2.5 to 1.5Mya from Africa.

 

However he goes on to caution that the site investigation at that stage was far, far from complete and would need a huge amount of systematic work, particularly of stratigraphy to draw any firm conclusions.

 

In 1983, Mochanov was back excavating again. He continues his description of the excavations, noting that by the end of this season 1300 quartzite artifacts of the same type found in the previous year had been found and that the site had expanded to cover 3000m². Some further commentary follows, reinforcing his belief that the site’s lithic assemblage resembled the Oldowan industry of Africa. He notes the discrepancy between the PAE (Prelinsk Archaeological Expedition) view of the site stratigraphy, that aeolian deposits overlay the cultural stratum and his assumptions of great age (dependent on then layers above the cultural bearing stratum 5 being of alluvial origin)  and decides more work needs doing on the site stratigraphy. Here is his description of that stratigraphy from 1983:

 

“In 1983 it was determined that the excavations, trenches, and test pits that the wind abraded quartzite artifacts on the 105-120m terrace were derived from the gravel-pebble-cobble deflated layer which was lying on the red-coloured fluvial sands..

(Deflation is defined as “The removal of surficial deposits of soil, sand or fine gravel by wind action.”) On a bedrock foundation of Cambrian limestone at an elevation of 105m +/- 2m.. It was observed that the culture-bearing stratum intersects the polygonal, sand filled ice-wedges, extends into the fluvial sands at 109-120m, and also intersects the lower gravels at 105-109m and in some places the eluvial top of the bedrock terrace.

In several places on the 105-120m terrace, chiefly at elevations greater than 108m, horizontally layered sandy deposits with cryogenic syngenetic textures and structures were recorded above the culture-bearing stratum and were assigned by us to the floodplain facies of the alluvium. Its thickness varied from 1 to 3.5m. The alluvial, owing to postdepositional denudation in some areas, mostly at the outer bench of the terrace, were marginally preserved or had lost their texture and structure, but in other areas they occurred as distinct ridges separated by furrows... The leaders of the A-14 (geological expedition mention above) had taken it (the sandy layers above the culture bearing stratum) for a dune and evidently therefore decided that its deposition was due to aeoliain processes. They adhered to this point of view until 1985. However in 1983 the PAE (Prelinsk Archaeological Expedition) had clearly noted that at the basal edge of the 105-120m terrace, the horizontally layered sands which covered the culture-bearing stratum were deposited as a sheet wash over the loamy-clay deposits of the 125-135m terrace, and for this reason they could not be aeolian.”

 

This is a key point in Mochanov’s argument. If the deposits above the cultural-bearing stratum are alluvial and not aeolian in origin, then the stratigraphy is intact and therefore the artifacts are EXTREMELY old as he has assumed all along. Mochanov concludes:

“Based on the geomorphological development of the middle Lena terrace, the 105-120m terrace was determined to be Cherendeisk or older, ..which contain the culture-bearing stratum - was restricted to the range of 2.4-1.5 million years.”

 

Here is a schematic view of the stratigraphy from Mochanov’s paper (2):

Mochanov’s schematic of the stratigraphy adapted from his 1993 (2) paper, note I have added a red line to indicate the cultural bearing layer, just above the v-shapes of the ice wedges. Original caption reads: Fig. 2. A. Schematic section of the Tabaginsk terrace in the vicinity of the Diring site. (a) Kembriisk (Cambrian) limestone; (b) gravel stratum2; (c) sand of stratum 3; (d) sandy Ice Wedges; (e) deflated culture bearing gravels; (f) sands, sandy loams and loams of strata 6-10; (g) sandy loams and loams of stratum 11; (h) sandy loams and loams of stratum 13; (i) sands of strata 12 and 14-18; (j) cultural remains of the Most Ancient Paleolithic; (k) drill cores; (l) numbers of the strata. B. (inset) Schematic profile of the locale showing the bedrock foundation of the terraces in the vicinity of the Diring site (not to scale).

 

In 1984 Mochanov was able to acquire more resources, in the form of a bulldozer, to test the extent of the cultural layers extending away from the river and under the higher terrace levels. During that season (2) and subsequently (4) 15850m² of sod was removed, and an area of excavations of 10220m² was excavated, of which 7743m² was the cultural bearing layer. In total 40m of overburden was removed from the centre of the site. By 1988 28 lithic clusters numbering thousands of artifacts had been recovered (4).

 

 

Diring Yuriakh upper site with overburden removed. Note the extreme depth of sediments removed at left of photograph.

Photo credit: Courtesy of the Center for the Study of the First Americans (3).

During the next part of the paper, Mochanov then theorises at length about the whole geological chronology of the Diring Yuriakh-Lena River watershed. Whilst interesting it has no bearing on the overall dating of the stratum 5, the cultural-bearing stratum.

He then to rebuts the views of Medvedev that “for wind abrasion (of the type seen at Diring Yuriakh) of stone to occur, severe artic desert conditions with continuous high velocity - more than 70m/s - were necessary” by detailing the palynological evidence that, pine, larch, fir, birch, bird cherry, alder and mountain ash grew in the region at the time and thus preclude the area being an artic desert. He further discounts this scenario by fairly pointing out that, if winds of this ferocity has scoured the site, the tiny pieces of flake debitage would now not remain in situ as they were indeed found.

 

He then attempts to justify ignoring the opinions of geologists Alexeev and Kamaletdinov that the stratigraphy has ..“inconvenient geological layers related to lake, slope and aeolian deposits” and their judgement that the maximum age down to the bedrock to be no more than a million years.

 

In summary Mochanov sees the entire deposition sequence above the bedrock, as being attributable to the fluvial/interfluvial cycle of the Lena River. Furthermore he sees the cultural-bearing layer as being formed, eroded, the artifacts being abraded by windblown sand, then re-buried by further fluvial/interfluvial cycles of the Lena River. Thus the dates of this layer MUST, according to his theory, be between 2.5 and 1.5 Mya. He notably chooses to ignore the opinions of the geologists that the lithic artifact-baring stratum has been buried by a layer of sediments which are of aeolian origin.

 

Of more interest is the single suspiciously (human?) fractured mammal bone of ungulate or proboscid origin. It was found in a concentration of lithic artifacts and is of obvious antiquity being entirely mineralised.

 

The lithics themselves are quite remarkable in their crudity and their obvious human manufacture.

 

Mochanov gives the following circumstances as indicating their human provenance:

·         The lithics are found in concentrations.

·         Lithics not randomly scattered across the landscape

·         Lithics found at maximum distances of 0.5Km from each other

·         Reconstruction of cores was possible using flake debitage

 

Characterising the concentrations of lithics, Mochanov notes that vast majority were of quartzite with a very low number of sandstone-quartzite artifacts also present. The concentrations of a few hundred artifacts occupied areas of about 100m². A typical assemblage of artifacts as for example from concentration 14 consisted of 18 kinds of ordinary choppers, multiedged macrochoppers one sharpened end microchopper (including one with a bill), one lateral microchopper, an example of the uniquely Siberian Skreblo -  a wide oval scraper, variously poorly formed tools, possibly resembling scrapers, knives, points or burins. Lastly a number of hammerstones and anvils. There was also considerable flake debitage, all the above grouped round a heavy cobble-anvil of dimensions 42 x 31 x 30cm.

Anvil on lag-surface

Photo credit: Courtesy of the Center for the Study of the First Americans (3).

Mochanov then freely admits just how basic and depauparate the assemblage is: “The basic distinction of the Diring Complex from the earliest African complex is the fact that at Diring multifaceted spheroids, bifacial discs, clearly expressed chopping tools, proto-axes, well-retouched small tools on chunks and flakes and above all, unmistakeable cores are lacking.”

Of final note in this paper is the claim that work by A. V. Pen’kov established a range of dates based on the paleomagnetic reversals above and below stratum 5 (the cultural-bearing layer). These ranged between “4.2-3.9 My (stratum 3), 3.15-3.0My (stratum 6, 7 and 8). A variation is possible as well 3.4-2.9 or 2.5 My. At present a “minimum” variation also cannot be excluded: 19.-1.7 My.”

 

 

What on Earth are we to make of all this? Oldowan type stone tools at an impossibly early date way out there in Siberia of all places? And the lead investigator at odds with his colleagues (I have only hinted at that - the detailed story shows far greater depths of disagreement)?

And yet.. and yet those tools are so obviously formed for human purposes.. the only real question is can we get REAL dates and then perhaps decide on the really juicy bit.. The WHO.. the which species of human!

 

 

Luckily for us someone did step up to try to bring some cold hard science to the site.. and luckily for us it was a well-respected outsider.. none other than Michael Waters of Buttermilk Creek fame (see here).

Here is how Waters (1) explains the stratigraphy of the site:

“At Diring, unconsolidated Quaternary sediments rest unconformably on Cambrian-age limestone. These Quaternary sediments are divided into four major stratigraphic units labeled I through IV (from oldest to youngest) and are further subdivided on the basis of lithostratigraphic criteria (Fig. 2). These sediments are of alluvial and eolian origin. The oldest unit that overlies limestone bedrock is composed of well-rounded gravel (unit Ia). Most of the gravels are pebble-sized and composed of quartzite. The gravels are conformably overlain by sands (unit Ib). The sand ranges from coarse-to-fine, angular-to-subangular grains that occur in horizontal beds and crossbeds. A few thin beds of well-rounded fine gravel and granules are interbedded in the sand. Unit I represents fluvial deposition in a sandy braided channel of an ancestral Lena River.

The gravel and sand (units Ia and Ib) are cut by two sets of wedges (3, 5) filled with sand (unit II). Wedges in the first set are large, ranging from 0.6 to 5 m wide and 4 m deep. Wedges in the second set are less than 0.5 m wide and reach a maximum depth of 1.1 m. All the wedges are filled with well-sorted, subangular medium sand. In some cases, small gravels (0.5 to 1 cm in diameter) form distinct vertical beds in the sand wedge fill. Large pebbles or cobbles are absent from both wedge sets. The sand from unit II is well sorted and the grains show evidence of wind abrasion; thus, the sand appears to be of eolian origin. The larger wedges appear to have been truncated by later deflation, whereas the smaller wedges extend downward from the deflation surface. Resting on top of the eroded surface of unit Ib and the truncated sand wedges (unit II) is a gravel lag. This is a loose lag with mostly small pebbles (92%), a few large pebbles (7%), and rare boulders (1%). Compositionally, most of the gravels are siliceous (70%), with the remainder composed of quartzite (20%) and vein quartz (10%). Most of the larger pebbles, and all cobbles and boulders, are quartzite. These quartzite clasts are generally well rounded.

All gravels are wind-abraded, showing pits, facets, and polish. This lag appears to have been created by the eolian deflation of unit I. The upper part of unit I must have contained lenses of gravel and large boulders that were deflated to a common surface and concentrated into a loose lag as the fine-grained sediments were removed when the wind swept over the area. The artifacts from Diring are found on this deflation lag.”

So an extremely simple stratigraphy then: the cultural-bearing stratum in an aeolian deflation lag and NOT of alluvial origin as Mochanov had assumed. In fact it was exactly what his own geologists had told him it was in 1983!

Walters 1997 Fig 2.(1) Original caption: Generalized cross section of the stratigraphy at Diring Yuriakh and associated TL ages. Solid triangles indicate the positions of the artifacts.

As can be seen from the diagram Thermoluminescence (TL) dating was used to date the sediments. Here is how Walters explains the method and his results:

“Thermoluminescence (TL) dating of sediments was the only acceptable technique available to assess the age of the stratigraphy and artifact horizon at Diring because of the proposed antiquity of the site and the absence of materials suitable for other dating methods. Loess and cover sands at Diring Yuriakh are suitable for TL dating because these sediments presumably received prolonged light exposure during subaerial eolian transport and deposition.

This process resets the TL signal to a low definable level. As a test, we exposed the sediment from Diring to sunlight for 16 hours. As a result, natural TL emissions were substantially reduced by .84%. A slightly greater reduction in TL occurred after 8 hours of exposure to an ultraviolet (UV) light–dominated source, which approximates sunlight exposure for .24 hours and provides a better estimate of the full solar resetting level. The 8-hour UV exposure values were used to calculate the TL ages reported here because they provide a maximum estimate of the predepositional TL level and a finite estimate on eolian deposition. The fine-grained (4 to 11 mm) feldspar-dominated fraction was used for dating because of the greater likelihood of solar resetting of the grains and because the grains are ubiquitous in the stratigraphic sequence. The paleodose was determined by the total-bleach technique; there was no discernable instability in the laboratory- induced emission. An attribute of the sediments from Diring that contributes to rendering TL ages >100 ka is the uniform and relatively low dose rate for loess and eolian sand units at 3.7 to 4.0 grays (Gy)/ka and 3.6 to 2.8 Gy/ka, respectively. We obtained nine TL ages at Diring. Fine-grained polymineralic samples from units IIIa and II (large truncated wedge) that bound the artifact-bearing horizon responded sufficiently to laboratory addititive dose and yielded ages of 267 +/- 24 ka (sample OTL471) and 366 +/- 32 ka (OTL472), respectively. .. The similarity among TL ages on polymineral samples and quartz grains, despite different levels of luminescence emissions, indicates that TL ages reflect burial time and are not an artifact produced by combining TL signals of various apparent ages. .. TL ages from the loess of unit IIIe that overlies the archaeological material at Diring provides a minimum age estimate for the artifact-bearing surface of about 260 ka, whereas the TL age from unit II underlying the artifact surface provides a maximum age of about 370 ka. The artifact surface, then, may date to about 300 ka.”

 

Whilst there has been some criticism of Walters’ TL methodology over the years, generally the sites’ antiquity is now well established.

 

Verdict:

 

Site inhabited ca. 300, 000 years ago.

 

Likely candidates Homo erectus or Homo heidelbergensis

 

 

References

1. Michael R. Waters, Steven L. Forman and James M. Pierson. 1997. Diring Yuriakh: A Lower Paleolithic Site in Central Siberia. Science Vol. 275 pp. 1281-1284. DOI: 10.1126/science.275.5304.1281

2. Mochanov, Y. A. 1993. The Ancient Palaeolithic Site of Diring and the Problem of a Nontropical Origin for Humankind. Arctic Anthropology vol. 30, no 1 pp22-53.

 3. Center for the Study of the First Americans. Retrieved from: http://csfa.tamu.edu/gallery.php

4. Carlson, R.L. 2001. Diring Yuriakh: An Early Paleolithic Site on the Lena River, Eastern Siberia. Indo-Pacific Prehistory Bulletin 21, (Melaka Paers vol. 5)