Friday, 18 December 2015

Did Chinese Homo erectus survive into the Late Pleistocene?

14,000-year-old hominin thigh bone has archaic affinities.

In 2012, human remains differing from the modern condition were reported from two sites 300 km (185 miles) apart in southwest China: Longlin Cave in Guangxi Province, and Maludong (‘Red Deer Cave’) in Yunnan Province. The Longlin remains have been radiocarbon dated to 11,500 years old, and those from Maludong to 14,000 years old. The Longlin remains included a partial skull, a temporal bone fragment probably belonging to the skull, a partial lower jawbone and some fragmentary postcranial bones. The cheek bones of the skull are broad and flared sideways; the browridges conspicuous; the chin less prominent than in Homo sapiens; and the remains are very robust. The Maludong remains include a skullcap, two partial jawbones and a partial thighbone.

Popularly reported as the Red Deer Cave people, the hominins were at first thought to represent a single population, but newly-published work suggests that the Longlin skull has affinities to early modern humans. The bony labyrinth (the bony outer wall of the inner ear) of the temporal bone fragment is modern in appearance and it is possible that the skull’s unusual shape might be the result of interbreeding between archaic and modern humans. It has been suggested that Longlin was located in a ‘hybrid zone’ – a border between relict archaic and modern populations. Similar hybrid zones occur with some non-human primate populations.

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The Maludong thighbone is now claimed to show affinities to archaic humans, in particular those from the Early Pleistocene. There is a scarcity of later archaic human remains in East Asia, and the authors of the new report are reluctant to assign the thighbone to a particular archaic human species. However, the likeliest possibility is that the thighbone represents a late survival of Homo erectus in China. Regardless of species, the implications of these new findings is that isolated populations of archaic humans were still in existence in China as late as 11,500 years ago and that some of these populations were interbreeding with modern humans.

References:

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1.  Curnoe, D. et al., Human Remains from the Pleistocene-Holocene Transition of Southwest China Suggest a Complex Evolutionary History for East Asians. PLoS One 7 (3) (2012).
2.  Curnoe, D., Ji, X., Taçon, P. & Yaozheng, G., Possible Signatures of Hominin Hybridization from the Early Holocene of Southwest China. Scientific Reports 5, 12408 (2015).
3.  Curnoe, D. et al., A Hominin Femur with Archaic Affinities from the Late Pleistocene of Southwest China. PLoS One (2015).
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Thursday, 19 November 2015

New dates for Monte Verde pushes back arrival of first humans in South America

Chilean site was first occupied at least 18,500 years ago

Monte Verde in southern Chile is a peat bog in the terraces of Chinchihuapi Creek in the Maullín river basin, midway between the Pacific coast and the Andean mountains. There is well-preserved evidence of human occupation including wooden tent remains, foundations and floors of huts, hearths, wooden lances, mortars, and large numbers of stone tools. The site was apparently occupied all year round. A wide range of coastal and mountain habitats were exploited including marshes, wetlands, forests, estuaries, and rocky and sandy shorelines.

Evidence of habitation was not thought to pre-date the 14,600 year horizon identified at the site MV-II, although there was evidence of an earlier cultural horizon (MV-I). The MV-II dates in themselves made Monte Verde attractive to opponents of the long-running ‘Clovis First’ orthodoxy, which holds that the culture originally identified at Clovis, New Mexico represents the earliest human settlement of the New World. The Clovis culture is noted for its distinctive leaf-shaped spear points, which were first found in the 1930s. Clovis sites dating from 13,250 years ago are widespread across the United States and Central America to as far south as Panama. Assuming that the first Americans reached the New World via the Beringia land bridge that linked Alaska with Siberia during the last Ice Age, a human presence in South America 14,600 years ago is problematic to Clovis First.  

However, even earlier dates have now been obtained for Monte Verde. Archaeologists carried out spatially-intermittent excavations and core drillings across an area lying between MV-II and the two sites of CH-I and CH-II, located on the south side of the creek, 500 m upstream of MV-II. These revealed stone tools, faunal remains, and evidence of fires widespread across the study area albeit vertically and horizontally discontinuous. These appear to represent ephemeral seasonal activities carried out over a long period of time between shallow channels of a now-buried braided system of streams that fed into the river. Radiocarbon and Optically Stimulated Luminescence dating has yielded a range of dates from 18,500 to 14,500 years ago, with implications that humans reached the New World much earlier than previously believed.

Reference
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Dillehay, T. et al., New Archaeological Evidence for an Early Human Presence at Monte Verde, Chile. PLoS One 10 (11) (2015).
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Wednesday, 18 November 2015

Homo erectus origin likely for Flores ‘hobbits’

Dental study rejects modern human or earlier hominin connection with Homo floresiensis

The origin of the diminutive ‘hobbits’ of Flores, Indonesia have been controversial since they were announced as a new human species, Homo floresiensis, in 2003. The most widely accepted view is that they are descended from a group of Homo erectus that reached Flores at least a million years ago and underwent a phenomenon known as insular dwarfism whereby a combination of low risk of predators and a relative scarcity of food means that smaller individuals are favoured from an evolutionary point of view and thus individuals within a population will ‘downsize’ over the course of many generations.
However, there are two alternative viewpoints. The first is that the Homo floresiensis remains simply represent modern humans affected by a condition such as microcephaly or cretinism. The second view accepts that the Flores hominins are indeed descended from an archaic species, but posit that it is something more primitive than Homo erectus – possibly Homo habilis or an australopithecine. It is argued that the absence of fossil evidence for such early hominins leaving Africa is not evidence of absence from Eurasia.

In a newly-published study, researchers carried out extensive comparisons using linear metric analyses, crown contour analyses, and other trait-by-trait morphological comparisons of the molar, premolar and canine teeth of Homo floresiensis against an extensive sample of teeth from present-day modern, prehistoric modern, and archaic humans. Three methods were used: metric analyses based on crown length and breadth data; comparisons of crown contour using normalized Elliptic Fourier Analysis (EFA); and non-metric and linear metric comparisons of individual morphological traits not recorded by the first two methods.

The researchers found suggest that the Homo floresiensis teeth do share derived characteristics with those of Early Pleistocene Homo erectus from East Africa and Java, and with the Dmanisi hominins from Georgia; but none of the ‘hobbit’ teeth exhibit the very primitive morphology associated with Homo habilis or australopithecines. Such characteristics include the occasional absence of a P3 buccal groove, a distally positioned P3 lingual cusp, a more circular P4 crown, the presence of a P4 transverse crest, non-parallelogram M2 crown shape, a mesiodistal short M2 crown, a M1 mid-trigonid crest, equivalent M1 and M2 sizes, and a moderately wide upper dental arcade. The findings rule out the claim that Homo floresiensis evolved from a hominin that was more primitive than Homo erectus.

Nor was a good match found with the modern samples. In comparison to Homo floresiensis, the teeth of Homo sapiens are derived for nine out of 26 character states, contradicting the suggestion that the dentition of Homo floresiensis is wholly modern.
Overall, the results suggest that Homo erectus is the ancestral species; however the dentition of Homo floresiensis did continue to evolve and possesses some unique features not seen in any other hominin species. These include the large (relative) size and the unique occlusal morphology of the P3 that otherwise exhibits primitive morphologies; and the extremely short first molars. In view of the general trend of molar shortening during the evolution of Homo over time, this condition in Homo floresiensis is actually more derived than in Homo sapiens.

It must be assumed that these evolutionary changes reflected the unique habitat of Flores, but regardless they demonstrate the distinctiveness of Homo floresiensis as a species.

Reference:
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Kaifu, Y. et al., Unique Dental Morphology of Homo floresiensis and Its Evolutionary Implications. PLoS One 10 (11) (2015).x


Thursday, 22 October 2015

Bronze Age origins of bubonic plague

Study finds evidence of Yersinia pestis bacterium in 5,000-year-old human teeth

Three pandemics of bubonic plague have occurred in historical times: the first began with Plague of Justinian from AD 541 to 544, continuing intermittently until AD 750 AD; the second began with the Black Death from AD 1347 to 1351, continuing in waves including the Plague of 1665-66 into the eighteenth century; and the third which started in China in the mid-nineteenth century and triggered a series of outbreaks worldwide during the first half of the last century. The Black Death alone killed 30 to 50 percent of the European population. Deaths totalled at least 75 million, more than the number of deaths during World War I and II combined.

The cause of this deadly disease was identified as the flea-borne bacterium Yersinia pestis in 1894 by Swiss biologist Alexandre Yersin. More recently, genetic studies have suggested that it diverged from the more widespread but less virulent Yersinia pseudotuberculosis anywhere between 2,600 and 28,000 years ago.
In a newly-published study, researchers investigated the origins of Y. pestis by sequencing ancient bacterial genomes obtained from the teeth of Bronze Age people across Eurasia dating from 2,800 to 5,000 years ago. Their findings indicate that the flea-borne strain that caused the historic period plague pandemics evolved from a less virulent strain that was present in human populations long before any records of plague outbreaks.

The strains infecting Bronze Age Eurasian populations lacked the Yersinia murine toxin (ymt) gene, which encodes a phospholipase D protecting the bacterium inside the flea gut, so enabling fleas to act as vectors. Similarly, mutations associated with the development of bubonic plague and evading mammalian immune systems had not yet occurred. Not until around 3,000 years ago did highly virulent, flea-borne strains emerge.

The researchers also estimated the divergence from Y. pseudotuberculosis at 55,000 years ago, twice as early as previous maximum estimates. The Bronze Age strains began to diverge from one another 5,800 years ago. Although they could not cause bubonic plague, they could still cause pneumonic and septicemic plague and these might have been responsible for population declines between the late fourth and early third millennium BC. Large scale population movements and social changes during the Bronze Age might have facilitated plague outbreaks, but not on the scale of the historical era flea-borne pandemics.

Reference:
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Rasmussen, S., Allentoft, M., Nielsen, K., Orlando, L. & Sikora, M., Early Divergent Strains of Yersinia pestis in Eurasia 5,000 Years Ago. Cell 163, 571-582 (2015).x

Friday, 16 October 2015

Modern humans were in China 100,000 years ago

Assignment of fossil teeth from Fuyan Cave to Homo sapiens is ‘unequivocal’

Ever since genetic evidence emerged to support the ‘recent Out of Africa’ model of modern human origins, the orthodox view is that until around 60,000 years ago modern humans were confined to Africa and a short range extension into Southwest Asia. The latter is thought to have been brought to an end as colder, more arid climatic conditions set in around 90,000 years ago. The model has been challenged by archaeological evidence suggesting that modern humans were established on the Arabian Peninsula 125,000 years ago and had reached India 77,000 years ago.

What has up until now been lacking is unequivocal fossil evidence significantly earlier than around 45,000 years old. Controversial evidence had previously been reported from two sites in southern China. An age of up to 139,000 years old has been claimed for the Liujiang Skull, discovered in 1958, but the exact geological position of the find was not documented and the skull could actually be as little as 30,000 years old. A lower jawbone and two molar teeth from Zhirendong (‘Homo sapiens cave’) in Guizhou Province have been securely dated to 106,000 years old, but it is not certain that these remains belonged to a modern human.

However, the discovery has now been reported of 47 teeth at the newly-excavated site of Fuyan Cave in Daoxian, Hunan Province. Uranium series dating of associated stalagmite fragments gave a minimum age of 80,000 years old for the teeth and faunal dating gave a maximum age of 120,000 years old. The teeth were compared with those of Late Pleistocene humans from Europe, Asia and Africa and were found to fall consistently within the Homo sapiens size range. They are generally smaller than other Late Pleistocene samples from Asia and Africa, and are closer to European Late Pleistocene samples and the teeth of present-day people. They resemble the latter far more closely than they do the teeth of Neanderthals or Homo erectus.

The announcement adds a radical new dimension to the history of modern human dispersals in Eurasia.

Reference:
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Liu, W. et al., The earliest unequivocally modern humans in southern China. Nature 526, 696-699 (2015).x


Wednesday, 14 October 2015

Ancient DNA reveals more extensive Neolithic back migrations to Africa from Eurasia

Sequenced genome of 4,500-year-old Ethiopian male provides genetic baseline for researchers

Modern humans are generally accepted to have originated in Africa, and the genomes of native Africans is therefore of great importance in reconstructing early migrations as our species dispersed around the world as it provides a baseline against which later events can be viewed. A problem for geneticists is the back migrations from Europe and Southwest Asia that have occurred within historical times, which act as a confounding factor when working with genetic data from present-day populations.

One way by which the problem could be solved is to obtain ancient DNA from prehistoric human remains, but this has proved difficult with only mitochondrial DNA being obtained up until now. However, in 2012, archaeologists excavated the burial of an adult male in Mota Cave, a riverside cave discovered the year before in the highlands of southwestern Ethiopia. Radiocarbon remains established that the remains were 4,500 years old, predating Eurasian migrations and the dispersal of Bantu farmers which spread agriculture across much of sub-Saharan Africa.

Conditions in the cave favoured the survival of ‘Mota’s’ DNA and it proved possible to sequence his genome. It was found that he was closely related to present-day Ethiopian populations, and in particular to the Ari, a group of Omotic speakers from southern Ethiopia, located to the west of the highland region where Mota lived. This was unsurprising and confirmed the view that there had been population continuity in this relatively isolated region over the last 4,500 years.

The researchers then searched for the source of the later Eurasian admixture by assuming that the present-day Ara genome is a genetic mix of Mota plus the source. It was found that the closest match was with Neolithic LBK farmers from Stuttgart and with present-day Sardinians. The latter are known to be the closest contemporary match to early Eurasian Neolithic farmers. The implication is that the genetic backflow into Africa came from the same source as the Neolithic expansion into Europe from Anatolia. These farmers were presumably responsible for the archaeologically-attested arrival of wheat, barley and other domesticated Southwest Asian crops in Africa around 3,000 years ago.

The next step was to use Mota as an African genetic baseline and the Neolithic LBK as the source of the Eurasian component to estimate the magnitude and geographic extent of historical migrations, without having to use present-day populations. It was found that the Eurasian genetic backflow was substantially higher than previously believed, with an additional 4 to 7 percent of the genome of most African populations tracing back to a Eurasian source. The geographical impact was also far greater than previous estimates suggest, extending all the way to West and South Africa. Even the Yoruba and Mbuti, often used as baselines in genetic studies, were found to have a significant Eurasian component, albeit less than in East Africa.

The Mota data has thus proved to be extremely informative about Neolithic migrations and obtaining even earlier African genomes would be highly desirable. Unfortunately, the African climate does not favour the preservation of DNA, but it is to be hoped that as sequencing techniques improve more ancient African genomes will become available.

Reference:
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Llorente, M. et al., Ancient Ethiopian genome reveals extensive Eurasian admixture throughout the African continent. Science 350 (6262), 820-822 (2015).
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Wednesday, 30 September 2015

Congenital defect is possible further evidence of inbreeding by Neanderthals at El Sidrón

High incidence of congenital clefts of the arch of the atlas observed among remains from Spanish site

The Atlas (C1) vertebra is the first cervical vertebra of the spine, immediately below the skull. It takes its name from the Greek Titan Atlas, who is popularly (but incorrectly) supposed to have held the world on his shoulders. Congenital defects of the anterior or posterior arches are rare in modern populations, occurring at frequencies of 0.087 to 0.1 percent and 0.73 to 3.84 percent respectively. The condition does not normally lead to clinical symptoms.

El Sidrón is a cave site in Asturias, northern Spain that has yielded extensive Neanderthal remains and stone tools since these were first discovered there in 1994. Over 2,400 human fossils have been recovered, representing at least thirteen individuals including seven adults, three adolescents, two juveniles and one infant. The remains are 49,000 years old. Ancient DNA has previously been obtained from the remains, indicating a small patrilocal (mature males remain within their family birth group, but females come from outside) group with low genetic diversity. Dental hypoplasias indicate that around half of the group members had experienced episodes of growth arrest due to malnutrition.

Researchers now report that two out of just three well-preserved atlases from the site present respectively a defect of the posterior arch and the anterior arch. Such a high incidence of a rare condition could be interpreted as further evidence of low genetic diversity of the group, and as a possible indicator of inbreeding. The picture that emerges from El Sidrón is of a small, barely-viable Neanderthal group struggling for survival in extremely harsh conditions.

References
:Ríos, L. et al., Possible Further Evidence of Low Genetic Diversity in the El Sidrón (Asturias, Spain) Neandertal Group: Congenital Clefts of the Atlas. PLoS One 10 (9), e0136550. (2015).

Friday, 11 September 2015

Hitherto-unknown early human species discovered deep inside Rising Star Cave, South Africa

A team led by Lee Burger has announced the discovery of a new species of early human.

Professor Berger, an American palaeoanthropologist working at the University of the Witwatersrand, Johannesburg, is known for Australopithecus sediba, announced in 2010 and at the time was the first new hominin species to be discovered in South Africa for decades. The discovery was when Matthew, Lee’s nine-year-old son, discovered a hominin collar bone embedded in a rock at Malapa, part of a now-eroded cave system near to Sterkfontein and Swartkrans, where many important hominin finds have been made.

Berger felt other cave systems in South Africa had the potential to yield hominin fossils, so in 2013 he recruited a team of cavers to search the Rising Star cave system, 50 km (30 miles) northwest of Johannesburg. The cave has been well explored over the years, but the team came across a narrow 18 cm (7 in.)-wide shaft that dropped vertically for 12 m (39 ft.) into an unexplored chamber. The cavers descended into the chamber and saw a fossil skull and jawbone lying on the floor of the cave. Berger believed that there were hominin fossils and obtained funding from the National Geographic for an expedition.

But to access what became known as Dinaledi Chamber (‘chamber of stars’) was problematic. Before they could even reach the narrow shaft leading down to the chamber, researchers, researchers would have to pass through another tiny shaft known as Superman’s Crawl and then climb a steep section known as Dragon’s Back. Berger placed an advertisement on Facebook for ‘small, skinny’ scientists believing at best there might be three or four people in the world who would fit the criteria. In the event, within days 57 suitable candidates had applied from which he chose six, all women. Within a month, the Rising Star Expedition had set up camp at the cave system and excavations commenced. Working in six-hour shifts, the six women soon recovered more fossil material than had been found in the whole of South Africa in the previous 90 years. Meanwhile, back on the surface, a large team began preparing and cataloguing the fossils, making full use of social media to report progress. A total of 1,550 fossils were recovered, comprising 15 individuals, including males, females and infants.

Berger then invited thirty young postdoctoral researchers from fifteen countries to help him evaluate the haul at a workshop in Johannesburg. They were accompanied by twenty of Berger’s more senior colleagues, who had worked with him on the Australopithecus sediba discovery. This unusual move did not please everybody and some questioned the wisdom of handing over such important fossils to inexperienced researchers.

The findings have now been announced. The remains represent a new human species, Homo naledi, named for the word ‘star’ in the local Sotho language. The new species is comparable in height and weight to a small-bodied modern human or a large australopithecine, with an estimated stature of around 1.5 m (5 ft.) and weighing 40 to 55 kg (88 to 121 lb.). The brain is tiny, ranging from 465 to 560 cc, overlapping entirely with the range of values known for australopithecines. The reconstructed skeleton exhibits both humanlike and apelike features, but in a combination that has not been seen with other hominins. The feet and lower limbs are humanlike, but the upper thighbone, pelvis and shoulders are apelike. The hands and wrists are humanlike, though the fingers are curved suggesting that it spent some of its time in the trees as well as on the ground. Overall, Homo naledi is the most primitive, small-brained hominin ever to have been included in Homo, but the shape of cranium and lower jawbone and the dentition suggest that it is human rather than an australopithecine.

Unfortunately, no dates have yet been published for the fossils. They are presumably too old to be radiocarbon dated, but there is no readily-datable material in the chamber. Calcium carbonate flowstones have been found to have been contaminated with materials from associated muds, making them unsuitable for uranium series dating. All we currently have to go on is the primitive characteristics such as the small brains. These suggest that Homo naledi emerged close to the base of the human family tree 2.5 to 2.8 million years ago. But until we have dates for the fossils, or other fossils turn up that can be dated, it will be difficult to say just where Homo naledi fits into the overall picture of human evolution.

Also troublesome is the question of how the fossils reached Dinaledi Chamber in the first place. There is a near-absence of non-hominin fossils in Dinaledi Chamber – yet these are abundant in the adjacent Dragon’s Back. This rules out the remains having being swept into Dinaledi Chamber by a flash flood, as this would have left a mixture of hominin and non-hominin remains in both chambers. Carnivores are also ruled out: even if there was a carnivore that preyed exclusively on Homo naledi, why would it drag its prey into such an inaccessible location? In any case, none of the bones showed any evidence of having been gnawed by carnivores. Nor does it seem that the hominins fell down a shaft leading into the cave from the surface: there is no evidence that any such shaft had ever existed. The fossils accumulated over time, so it can also be ruled out that a single group entered the chamber for some reason and then become trapped there.

The only obvious explanation is that the remains were deliberately placed in the chamber as part of a post-mortem ritual, although there is no evidence for such rituals until much later. Mass deposition of corpses is first seen at the cave site of Sima de los Huesos in Spain, 430,000 years ago. Even this was nothing more than a hygienic disposal of the corpses rather than any form of ritual. Also, unlike Homo naledi, the brain size of the Sima people was only slightly below that of modern people. In any case, even hygienic disposal seems unlikely as there is no evidence that Rising Star was ever inhabited, and there would surely be no need to use such an inaccessible chamber.

Taken at face value, the evidence from Dinaledi Chamber suggests that early humans were far more behaviourally complex than has long been believed. However, it is probably too soon to jump to conclusions and all that can safely be said is that we don’t yet know how the fossils reached the cavern.

References:

1. Berger, L., Hawks, J., de Ruiter, D. & Churchill, S., 2015. Homo naledi, a new species of the genus Homo from the Dinaledi Chamber, South Africa. eLife.
2. Dirks, P. et al., 2015. Geological and taphonomic context for the new hominin species Homo naledi from the Dinaledi Chamber, South Africa. eLife.


Thursday, 3 September 2015

Radiocarbon dates used to trace possible origins of domesticated rice

Seven models tested against extensive archaeological database

Rice is one of the world’s most important cereal crops, and has supported dense human populations in Asia since Neolithic times. The origin and spread of domesticated rice is understandably of great interest to students of Asian prehistory and researchers have employed a variety of methods, including genetics, phytolith studies, from the presence of charred grains in archaeological excavations, and from rice husks in Neolithic pottery.

In a newly-published study researchers have made use of an extensive database of radiocarbon data from 400 sites spanning 470 phases of occupation in mainland East, Southeast and South Asia. The researchers modelled the likely spread of rice agriculture using an algorithm known as Fast Marching, which was used to estimate least-cost distances based on simple geographical features and suitability of regions for rice agriculture. Existing knowledge of archaeological evidence for rice was used to infer backwards towards probable areas of origin for rice cultivation. The researchers also used goodness of fit to test various previously-published hypotheses of the origin of rice agriculture against the overall archaeological rice database.

The unconstrained search for the most likely origin identified a region between the Lower and Middle Yangtze, specifically the northeast of Jiangxi Province, where there is little archaeobotanical evidence for early rice agriculture. However, the algorithm was trying to find the best-fitting single source and was unable to identify multiple origin scenarios. In such cases, it will highlight an area in between the various true origins.

The next step was to test seven previously-published hypotheses, labelled L1 to L7 in the study:
L1 Ganges, Burma and northern Vietnam
L2 Ganges, Northern Thailand and lower Yangtze
L3 Middle Yangtze and northern Bay of Bengal
L4 Pearl River delta
L5 Middle Yangtze
L6 Lower Yangtze
L7 Middle and Lower Yangtze

Of these, the last model, favouring two independent origins in the Middle and the Lower Yangtze, gave the best fit with the data and is also the most consistent with the unconstrained search. The authors of the report claim that the L7 ‘dual Yangtze’ model is so well supported over the second-best match, the L6 Lower Yangtze scenario, that the situation is compared to randomly drawing 125 million white balls out of an urn and asking whether this is sufficient evidence that the urn contains only white balls, versus containing an equal amount of white and black balls.

Whether such optimism is justified, only time and further studies will tell. However, the results agree with the conclusions of many archaeologists who have recently focused on the Middle and Lower Yangtze basin. There is currently no reason to favour either over the other as a more likely source region of rice domestication episode. Instead, multiple, distinct domestication episodes seems the most plausible hypothesis in the current state of our evidence. Cultural differences between the Neolithic traditions of the Lower and Middle Yangtze, including the earliest preserved field systems, makes it unlikely that rice agriculture diffused between the two regions.

References:
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Silva, F. et al., Modelling the Geographical Origin of Rice Cultivation in Asia Using the Rice Archaeological Database. PLoS One 10 (9), e0137024. (2015).x


Sunday, 23 August 2015

Mass grave at Schöneck-Kilianstädten reveals Neolithic massacre

 Chilling discovery at LBK site in Germany

Schöneck-Kilianstädten is a Neolithic mass grave in Hesse, Germany, which was discovered by chance in 2006 during road building works. The site is associated with the Linearbandkeramik (Linear Pottery) Culture or LBK, a Neolithic farming culture that emerged in Hungary around 5600 BC. The LBK is named for its distinctive pottery with banded incised decoration, and it is noted for its characteristic settlements comprised of clusters of massive timber-built longhouses, sometimes measuring up to 70 m (230 ft.) in length.

The LBK was a widespread phenomenon. LBK farmers spread rapidly across Central Europe, their dispersal probably aided by boats. They reached the Rhineland by 5300 BC, followed by the Paris Basin and they also spread eastwards as far as Ukraine and Moldova. Despite its success, evidence has emerged over the last thirty years that relations between LBK farming groups were not always positive.

A mass grave known as the Death Pit at Talheim, Germany, was found in 1983. It contained the remains of 34 individuals, including women and children, most of whom showed evidence of violence. Victims had been hacked or bludgeoned to death with stone adzes and three had been struck by arrows. The use of Neolithic stone tools as murder weapons suggests that the attackers were neighbouring LBK farmers rather than local hunter-gatherers, though the motive remains unknown.

Another example of internecine violence between LBK communities was found at the site of Schletz, Austria, where the remains of 67 individuals were found in an enclosure that was probably built as a defensive structure in an ultimately unsuccessful attempt to keep hostile neighbours at bay. Here again, the victims were bludgeoned to death with stone adzes, ruling out a clash with local hunter-gatherers.

However, the most disturbing find to date is a mass grave discovered by chance during road building work at Schöneck-Kilianstädten, Germany, in 2006. The grave dates to around 5000 BC and it has now been reported that it held the remains of at least 26 individuals including 13 predominantly male adults, one young adult and twelve children, mostly aged no more than six years old. The youngest was just six months old. The bodies had been dumped in the burial pit without any of the grave goods that normally accompanies LBK burials.

Again, the skulls showed signs of violence, but there was an additional find. Around half of the shin bones recovered from the grave had been freshly broken and while the corpses could have been systematically mutilated after death, the more sinister possibility is that individuals were tortured before they were killed.

These three sites, widely separated geographically but all dating to the later stages of the LBK, paint a grim picture of widespread violence in Neolithic Europe.

Reference:


Meyer, C., Lohr, C., Gronenborn, D. & Alt, K., 2015. The massacre mass grave of Schöneck-Kilianstädten reveals new insights into collective violence in Early Neolithic Central Europe. PNAS, 8 September, 112(36), pp. 11217-11222.

Saturday, 15 August 2015

Still no consensus on cause of Late Quaternary mass extinction

Studies reach opposite conclusions on humans vs climate change debate

The cause of the mass extinction of megafauna (land-living species with an adult mass of over 45 kg (100 lb)) during the last Ice Age has been debated since the late eighteenth century. Two main theories have predominated for much of that time: human causation and climate change. Two new studies, published in the journals Science and Ecography respectively, suggest that the debate is set to continue.

In the first study, published in Science, an Australian team compared ancient DNA and radiocarbon data from 31 detailed time series of regional megafaunal extinctions and replacements over the past 56,000 years with standard and new combined records of Northern Hemisphere climate in the Late Pleistocene. The researchers used ancient DNA to identify particular species, claiming that this is more reliable than traditional means of identifying fossil remains at species level. It was found that extinctions peaked during abrupt warm climatic episodes known as Dansgaard-Oeschger events, and the researchers claimed that it was these that had been primarily responsible for the extinctions, with human impact as no more than an exacerbating factor.

The second study, conducted at the University of Exeter and published in Ecography, reached the exact opposite conclusion. In this study, the researchers searched for all published records of dated remains or extinction estimates for terrestrial animal genera potentially present in the past 80,000 years with an adult mass of at least 40 kg (88 lb). In this case, there was no attempt at species-level resolution. By this means, last appearance dates were obtained for megafauna in 14 regions across the Americas, Eurasia, Africa, Australia, Tasmania, New Zealand, New Guinea and Madagascar. These dates were compared with dates of human arrival and episodes of climate change. It was concluded that the extinctions were primarily linked to the former and that the latter was only a secondary factor.

While these studies, with their very different methodologies, make a valuable contribution to our understanding of the Late Quaternary mass extinction, they do illustrate the point that it is very hard to make a convincing case for either climate change or humans being solely responsible on a worldwide basis. Overall, it seems likely that different factors operated in different places and at different times.

References:
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Bartlett, L. et al., Robustness despite uncertainty: regional climate data reveal the dominant role of humans in explaining global extinctions of Late Quaternary megafauna. Ecography (2015).
Cooper, A. et al., Abrupt warming events drove Late Pleistocene Holarctic megafaunal turnover. Science 349, 602-606 (2015).

Wednesday, 29 July 2015

Peopling of the New World remains contentious

New genetic studies reach differing conclusions

It is generally accepted that the humans first reached the New World by crossing the land bridge between Siberia and Alaska during the last Ice Age. However, the number of migrations and their timing has been debated for many decades.

The Paleoamerican model states that the earliest Americans or Paleoamericans were replaced by a second, separate wave of migrants from which today’s Native Americans are descended. The model is based on apparent differences in craniofacial morphology between some early fossil remains and more recent Native American. Note that this hypothetical second migration is distinct from the much later migrations responsible for around half of Aleut-Eskimo ancestry, and a tenth of Na-Dene ancestry.

Two new studies, published respectively in the journals Science and Nature, have reached opposing conclusions. Publishing in Science, Raghavan and colleagues analysed whole genomes of 31 present-day people from the New World, Siberia and Oceania, 23 ancient New World genomes and single nucleotide polymorphism genotypes from 79 present-day people from the New World and Siberia. The ancient DNA included samples from a 4,000 year-old Saqqaq individual from Greenland and the 12,600 year-old Anzick-1 (Clovis culture) individual from Montana.

They found that the ancestors of all present-day Native Americans, including Athabascans and Amerindians, entered the New World in a single migration from Siberia no earlier than 23,000 years ago and after no more than 8,000 years of isolation in Beringia. Around 13,000 years ago, these ancestral Native Americans diversified into two basal genetic branches: one that is now dispersed across North and South America and another restricted to North America. Subsequent gene flow resulted in some Native Americans sharing ancestry with present-day East Asians, including Siberians and, more distantly, Australo-Melanesians. But populations believed to be relict Paleoamericans including the Pericúes from Mexico and the Fuego-Patagonians, are not directly related to modern Australo-Melanesians, contrary to the predictions of the Paleoamerican Model.

The second study, published by Skoglund and his colleagues in Nature, featured genomic data from 63 Native Americans, who belonged to 21 diferent populations, and showed no discernable evidence of European or African ancestry. Results showed that some Amazonian Native Americans descend partly from a founding population with an ancestry more closely related to Aboriginal Australians, New Guineans and Andaman Islanders than to any present-day Eurasians or Native Americans. This genetic signature is not seen in present-day Northern and Central Native Americans, or in the Anzick-1 genome. The source population for this Australasian-related ancestry was named ‘Population Y’ after Ypykue´ra, which means ‘ancestor’ in the Tupi language family spoken by the Suruı´ and Karitiana.

The researchers suggested that Population Y had already admixed with a lineage related to First Americans by the time it reached Amazonia, and that it was the explanation for the differing craniofacial morphology noted above. However, no ancient DNA directly extracted from remains with this morphology, so the results did not prove that these people were Population Y. The absence of linkage disequilibrium in Population Y suggests that it arrived in the New World a long time ago. Furthermore, while it shows a distant genetic affinity to Andamanese, Australian and New Guinean populations, it is not particularly closely related to any of them, suggesting that its ultimate source in Eurasia no longer exists.

It is to be hoped that future ancient DNA studies provide further insight into the results of the Skoglund study.

References:
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Skoglund, P. et al., Genetic evidence for two founding populations of the Americas. Nature 525, 104-108 (2015).
Raghavan, M. et al., Genomic evidence for the Pleistocene and recent population history of Native Americans. Science 349 (6250), 841, aab3884-1-10 (2015).x


Thursday, 23 July 2015

Ohalo II ‘proto-weeds’ indicate attempts to cultivate wild cereals 23,000 years ago

Evidence of low-level food production at Epipaleolithic site

Ohalo II is a well-studied sedentary hunter-gatherer settlement on the shores of the Sea of Galilee. Associated with the Kebaran culture, the site dates to the Early Epipaleolithic period and was occupied around 23,000 years ago. The partially-excavated site is believed to cover an area of around 2,000 sq. m. (21,500 sq. ft.), and excavations have revealed the remains of six huts. Faunal remains suggest that the Ohalo II people hunted gazelle and deer, trapped hare and birds, and caught fish. From preserved botanical remains, no fewer than 142 different plant species have been identified, including emmer wheat, barley, brome and other small-grained grasses, acorns, almonds, pistachios, olives, legumes, raspberries, figs and grapes. These were collected from a range of habitats, including the nearby Mount Tabor.

In a newly-published report, archaeologists report the identification of 13 plant species now classified as weeds, mixed with large quantities of wild cereal seeds, including emmer, barley and oats. The presence of such species among cereals is considered to be one of the key archaeological indications of food production – in this case some 11,000 years before the onset of full-blown agriculture in the region.

That the Ohalo II people were harvesting wild cereal stands is supported by a study of glossed flint blades found at the site. The pattern of use-wear ‘sickle gloss’ polish observed on the sharp edges of these blades is consistent with their use to harvest wild cereals before they fully ripen and scatter their grain. Such a practice known from the later Natufian culture, but has not previously been documented for the Kebaran.  The blade also bears traces of hafting on the opposite side to the cutting edge, indicating that it was possibly a part of a sickle. Again, such tools are very rare in a pre-Natufian context.

However, the report suggests that these techniques were not carried on in later times, and they evidently represent a failed attempt at low-level food production. Sickle-harvesting did not come into widespread use until the Early Natufian around 8,000 years later, or 15,000 years before the present.

Reference:
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Snir, A. et al., The Origin of Cultivation and Proto-Weeds, Long Before Neolithic Farming. PLoS One 10 (7), e0131422 (2015).
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Wednesday, 22 July 2015

Earliest evidence of dentistry in Late Upper Palaeolithic

Stone tools used to treat dental caries 14,000 years ago

Humans have been practicing dentistry for a surprisingly long time. The earliest dental filling, made from beeswax and dating to 6,500 years ago, was reported from Slovenia in 2012 and a bow drill was apparently used to remove decay from molar teeth recovered from a 9,000-year-old Neolithic graveyard in Pakistan. The increase in carbohydrate consumption in the Neolithic was accompanied by an increase in dental caries, and a need for dentistry. The drilling, cleaning and filling dental cavities is documented in ancient Egyptian texts, which confirm that the practice was established by at least the fifth millennium BC.

Evidence of a much earlier origin for the treatment of dental caries has now emerged from Epigravettian site of Riparo Villabruna in northern Italy. Researchers studied a lower right third molar from a 25-year-old male, originally recovered in 1988 and radiocarbon dated to around 14,000 years ago. They noticed a dental cavity that had apparently been cleaned and on investigating with an electron microscope they found V-shaped striations that appeared to have been caused by scraping.

The researchers then attempted to replicate the striations on recently-extracted third molars, using pointed tools made from wood, bone and microlith. The use of such tools as toothpicks is well documented from the Palaeolithic. It was found that the microlith tool produced grooves and ridges matching those found on the Villabruna tooth, which thus provides the earliest known example of dental surgery. The cavity had been dug with a flint microlith to remove the dental decay and presumably relieve toothache.

The Villabruna specimen suggests that there was at least some knowledge of dental disease treatment well before the Neolithic. This study suggests that early forms of carious treatment entailed an adaptation of a toothpick to lever and scratch out decay rather than the drilling practices of later times.

Reference:
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Oxilia, G. et al., Earliest evidence of dental caries manipulation in the Late Upper Palaeolithic. Scientific Reports (2015).
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Wednesday, 24 June 2015

Early modern human from Romania had recent Neanderthal ancestor

Ancient DNA from Peştera cu Oase demonstrates inbreeding no more than four to six generations previously

The cave site of Peştera cu Oase (‘Cave with Bones’) in Romania has yielded some of the earliest fossil remains of modern humans in Europe. The remains of three individuals recovered from the site include a largely-complete lower jawbone (Oase 1), the near-complete skull of a 15-year-old adolescent, and a left temporal bone. The remains are around 40,000 years old and exhibit a mosaic of modern and archaic features. Modern features include the absence of browridges, a narrow nasal aperture, and a prominent chin; but there are also archaic features such as a wide dental arcade and very large molars. There is little doubt that they are modern humans and not Neanderthals, but some aspects of the morphology are consistent with Neanderthal ancestry.

Researchers have now recovered ancient DNA from the Oase 1 jawbone and sequenced the genome. They report that between 6 to 9 percent of the genome is of Neanderthal origin, a higher percentage than for any other modern human genome sequenced to date. Three chromosomal segments of Neanderthal DNA are of considerable length, suggesting that the Neanderthal contribution to the Oase 1 individual occurred so recently in their past that the chromosomal segments of Neanderthal origin had little time to break up due to recombination. The researchers turned their attention to seven segments of the genome that appeared to be of recent Neanderthal origin and from the genetic lengths of these, implied that Oase 1’s Neanderthal ancestor had lived no more than four to six generations earlier, or less than two hundred years.

The existence of such a recent Neanderthal ancestor casts doubts on theories that suggest that interbreeding occurred only very occasionally, or was confined to an early episode soon after modern humans first left Africa. However, the researchers failed to establish a clear relationship between the Oase 1 individual and later modern humans in Europe, suggests that they may have been a member of an early modern human population in Europe that eventually died out without contributing much to later European populations.

Reference:
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Fu, Q. et al., An early modern human from Romania with a recent Neanderthal ancestor. Nature 524, 216-219 (2015).

Friday, 19 June 2015

Kennewick dispute set to reignite

Ancient DNA confirms Native American affinities

Kennewick Man died about 8,600 years ago and was between 40 to 55 years old at the time of his death. In 1996, his skull and some other skeletal parts were discovered in the Columbia River, Kennewick, Washington State. The find was of interest not just to anthropologists but also to Native Americans, who refer to him as the Ancient One. The Plateau people of the Pacific Northwest claimed an ancestral relationship and requested repatriation of the remains as provided for under US federal law (Native American Graves Protection and Repatriation Act or NAGPRA). The land where the remains were found is managed by the US Army Corps of Engineers, who announced that they were willing to hand over the remains. This in turn precipitated a lawsuit from scientists wishing to study the remains.

The plaintiffs’ claim was based on the morphology of the skull, which is long and narrow, with a narrow face, and a jutting chin. It is quite unlike the broad-headed, broad-faced appearance typical of Native Americans and resembles that of certain Pacific populations, in particular the Ainu and Polynesians. It was argued that Kennewick Man belonged to a population that reached America before the ancestors of the present-day Native Americans, and that the request for repatriation of the remains must therefore be rejected. In 2004, the plaintiffs’ claim was upheld by a judicial ruling.

However, subsequent discoveries have cast doubt on the claim that Native Americans are descended from migrants that replaced an earlier American population. Remains have been found that are even older than those of Kennewick Man, yet fall comfortably within the morphological range of present-day Native Americans. Other remains have yielded mitochondrial DNA belonging to haplogroups only found in Native American populations. Genetic studies have failed to find any evidence for a replacement of early Paleoindians by ancestors of today’s Native Americans.

It has been suggested that skull data has simply been misinterpreted. In one study, researchers applied statistical methods to skulls from all over the world, dating from around 15,000 years ago to the present day. They found that when shape variation was considered over a wide geographical range or over a long period of time, the skulls formed a continuum rather than discrete categories. The same pattern was also seen when New World skulls were considered on their own. The supposed Paleoindian and Native American forms were no more than extremes at opposite ends of a continuum, and most of the New World skulls fell well between the two extremes.

Following the 2004 ruling, study of Kennewick Man continued, but only now have researchers obtained ancient DNA from the remains. A team led by Morten Rasmussen has published its results in the journal Nature and they show that Kennewick Man is more closely related to present-day Native Americans than to any other population worldwide. Based on a comparison with Native American groups for whom genome-wide data is available, several groups are apparently descended from population closely related to that of Kennewick Man, including the Confederated Tribes of the Colville Reservation (Colville), which is one of the five groups claiming Kennewick Man.

A renewed claim for repatriation now seems inevitable.

References:
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1.
Rasmussen, M., Sikora, M., Albrechtsen, A., Korneliussen, T. & Moreno-Mayar, J., The ancestry and affiliations of Kennewick Man. Nature 523, 455-458 (2015).
2.
Jantz, R. & Owsley, D., Variation Among Early North American Crania. American Journal of Physical Anthropology 114, 144-156 (2001).

Thursday, 18 June 2015

Did Aboriginal Australians rediscover boats after over 20,000 years?

Evidence for human activity on island in ancient mega-lake

Lake Mungo is the largest of a series of 19 now dried up lakes making up the Willandra Lakes system. The region is a World Heritage Site covering 2,400 sq. km (925 sq. miles) in southwest New South Wales, about 1,000 km (620 miles) west of Sydney. The water levels in the lakes remained high until 45,000 years ago and then began to decline. They dried up completely 22,000 years ago, and have remained dry ever since. However, a recent survey has shown that 24,000 years ago, Lake Mungo underwent a sudden massive filling episode, increasing its depth by 5 m (16 ft.) and its volume by 250 percent. Lake Mungo became linked to its neighbour, Lake Leaghur, at two overflow points, so creating an island in between.

Humans arrived in the Lake Mungo region at least 20,000 years before the mega-lake phase. The expansion of Lake Mungo would have substantially affected mobility, forcing people to skirt the mega-lake. However, the presence of hearths and stone artefacts on the island suggests that they repeatedly crossed the inflow channel, taking stone tools and hunting equipment with them. While they could have swum, using bags to carry tools, it is likelier that they used boats.

This implies a highly flexible response to the sudden change in conditions, and possibly a re-discovery of boat technology. While Aboriginal Australians must have used boats to reach Australia in the first place, there is a lack of evidence for pelagic fishing and navigation to offshore islands around the Australian coast until a few thousand years ago. It has accordingly been assumed that watercraft technologies were abandoned after initial arrival and dispersal across Australia. If boats were used to cross Lake Mungo during its expanded phase 24,000 years ago, then this represents the revival of a technology which had apparently been abandoned over 20,000 years earlier, and at a location well inland and far from any major navigable rivers.

Reference:
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Fitzsimmons, K., Stern, N., Murray-Wallace, C., Truscott, W. & Pop, C., The Mungo Mega-Lake Event, Semi-Arid Australia: Non-Linear Descent into the Last Ice Age, Implications for Human Behaviour. PLoS One 10 (6), e0127008 (2015).x


Saturday, 30 May 2015

Skull surgery used to treat post-traumatic osteomyelitis 4,900 years ago

Did Chalcolithic surgeons possess medical knowledge which remains poorly-understood to this day?

It sounds counter-intuitive, but there is some evidence to suppose that long-bone fractures heal faster if patients have also sustained traumatic skull injuries. The exact mechanism is not fully-understood, but may involve the cytokine interleukin-6, bone morphogenic proteins, and prolactin, all of which are released in response to a brain injury. What is remarkable is this might have been known in Chalcolithic times – and used as a treatment.

In 1992, archaeologists discovered the Early Chalcolithic cemetery of Pontecagnano in southern Italy, associated with the Gaudo Culture and dating to around 4,900 to 4,500 years ago. PC 6589.1 is a 25-year-old male, whose skull shows two lesions. The right thigh bone shows a poorly healed mid-shaft fracture, which had resulted in a chronic infection of the bone marrow known as osteomyelitis affecting both thigh bones.

The condition would have been disabling and was probably the ultimate cause of death, but an evidently-skilled prehistoric surgeon had attempted a cure. The skull lesions were the result of surgical trepanations of the skull cap, where holes had been made in the skull to expose the dura mater. One hole was apparently produced by scraping; the other by drilling with a stone point. There is evidence of significant bone regrowth, suggesting lengthy postoperative survival of the patient.

While the procedure was undoubtedly carried out with the intention of freeing the patient from his painful and disabling condition, the exact reason is not clear. The traditional explanation is that trepanning releases evil spirits associated with the symptoms affecting the patient, but it is possible that healers were aware of a strange curative phenomenon which modern medical science is only now rediscovering.

References:
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Petrone, P. et al., Early Medical Skull Surgery for Treatment of Post-Traumatic Osteomyelitis 5,000 Years Ago. PLoS One 10 (5), e0124790 (2015).x

Thursday, 28 May 2015

New hominin species reported from Ethiopia

Australopithecus deyiremeda was a contemporary of ‘Lucy’

Hominin remains comprising a complete lower jawbone, a partial lower jawbone and two partial upper jawbones, together with some accompanying teeth have been described as a new species, Australopithecus deyiremeda. The fossils were excavated in 2011 in the Woranso–Mille study area, central Afar, Ethiopia. They were found in deposits dated from 3.3 to 3.5 million years old, making Australopithecus deyiremeda a contemporary of Australopithecus afarensis (the species to which the well-known fossil ‘Lucy’ belongs) and the controversial hominin species Kenyanthropus platyops. The specific name deyiremeda means ‘close relative’ in the local Afar language and follows a now-established tradition of using local languages to name hominin species.

Australopithecus deyiremeda is distinguished from Ardipithecus ramidus by its thicker dental enamel and more robust lower jawbone. It is distinguished from Australopithecus afarensis by a number of features of its lower jawbone, by the positioning of its cheekbones in relation to the upper jawbone, and by its smaller back teeth.

What are the implications of this discovery? For a long time, it was believed that there was just the one hominin species, Australopithecus afarensis, living in the period from four to three million years ago, in East Africa. It was possible to argue that the earlier Australopithecus anamensis (4.2 to 3.9 million years ago) and the later Australopithecus garhi (2.5 million years ago) were simply early and late forms of the same species and that Australopithecus bahrelghazali from Chad (known from a single 3.5-million-year-old specimen) represented a Central African extension of its range. On this view, Australopithecus afarensis was a single, long-lived, geographically widespread species, capable of occupying a wide range of habitats. Not until 2.8 million years ago did other hominin species start to appear: Australopithecus africanus and later Australopithecus sediba in South Africa and the so-called robust australopithecines (Paranthropus) in both South Africa and East Africa.

Even if Kenyanthropus platyops is rejected, this view is no longer tenable. There is now incontrovertible evidence that multiple australopithecine species were living in East Africa during the Middle Pliocene. It is also notable that Australopithecus afarensis has been recorded at Hadar, only 35 km (20 miles) north of Woranso–Mille. Not only did these species overlap in time, they were close in geographical terms, probably occupying differing feeding niches.

 Early hominin evolution has been described as more of a tangled bush than a family tree. In addition to Australopithecus afarensis, Australopithecus deyiremeda and possibly Kenyanthropus platyops, it is likely that the Ardipithecus line was still in existence at this time. The Woranso–Mille site has also yielded a 3.4-million-year-old partial hominin foot with an opposable big toe. Though it has not been assigned to a particular species, the toe suggests Ardipithecus or something very similar.

With the LD-50-1 lower jawbone pushing back the origins of Homo to 2.8 million years ago, later australopithecines such as Australopithecus sediba have been bumped from the list of possible human ancestors. However, the Woranso–Mille discovery means that we are no nearer identifying from just which part of the ‘tangled bush’ the first humans emerged.

References:
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1.       Haile-Selassie, Y. et al., New species from Ethiopia further expands Middle Pliocene hominin diversity. Nature 521, 483-488 (2015).

Wednesday, 27 May 2015

Killed with a blunt instrument

Evidence for lethal interpersonal violence in the Middle Pleistocene

Evidence of interpersonal violence between humans resulting is (perhaps surprisingly) rare in the Pleistocene. Examples include the Shanidar 3 and St. Césaire 1 Neanderthals, from Iraq and southwestern France respectively. Shanidar 3 suffered a penetrating injury from a projectile weapon, and St. Césaire 1 suffered a fractured skull consistent with a deliberate blow from a sharp object. It cannot be ruled out that the injuries were the result of accidents: a hunting injury in the case of Shanidar 3 and a fall in the case of St. Césaire 1 (though the location of the injury at the apex rather than side of the cranial vault makes this unlikely). Neither incident was fatal, at least not immediately so, as both lived long enough thereafter for healing to begin. There are also cases where bones have been de-fleshed and broken open to extract marrow, suggesting cannibalism – although it is unclear whether individuals were attacked and killed, or whether they were already dead and possibly eaten by their companions.

The 430,000-year-old site of Sima de los Huesos (‘Cave of Bones’) in northern Spain has yielded a large number of human remains described as either Homo heidelbergensis or as proto-Neanderthals. The remains were found in a deep pit into which they were intentionally dropped, either as part of a mortuary ritual or more likely as a means of hygienically disposing of dead bodies.

Cranium 17 is a very complete cranium recovered in 52 pieces. It comprises the entire face, including much of the upper dentition (upper right C to M3 and upper left C to M2), the frontal bone, most of the sphenoid bone, the left parietal bone, the left temporal bone minus the mastoid process, and most of the occipital bone. The slight dental wear suggests that Cranium 17 belonged to a young adult.
Most of the fragmentation of the cranium involved dry bone breakage occurring long after death. 

However, there were two unhealed depressed fractures consistent with blunt force trauma from the same weapon (or ‘tool’ as the paper euphemistically describes it), resulting in penetration of the bone-brain barrier. Either injury would probably have been fatal: two suggests an intention to kill. Furthermore, the presence of two injuries caused by impact with the same object more or less rules out post-mortem damage to the cranium caused by it landing on a hard object when it was dropped into the pit, or by subsequent rock-falls.

Cranium 17 represent the earliest reasonably clear-cut case of interpersonal violence between humans leading to death. It demonstrates that this rather depressing aspect of human behaviour has an ancient origin.

References:

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Sala, N. et al., Lethal Interpersonal Violence in the Middle Pleistocene. PLoS One (2015).
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