Friday, 29 January 2016

Study refutes claim for early cat domestication in China

Quanhucun ‘cats’ were a different feline species

Genetic studies suggest that the domestic cat (Felis silvestris catus) is descended from the Near Eastern Wildcat (Felis silvestris lybica), a subspecies of the widely-distributed Old World Wildcat. The latter has been associated with humans since the early Neolithic, initially as a commensal that preyed on rodents and other pests in early faming settlements. A cat burial from Cyprus, dating to 7350 BC, shows that cats were valued by humans by this time, but domestication was a much later development. The Cypriot cat was large even for a wildcat and well above the size range for a domestic cat.

In 2014, archaeologists claimed to have found evidence for cat domestication in China from around 3500 BC. The Neolithic site of Quanhucun in Shaanxi Province is associated with millet farmers, who had evidently employed cats to tackle the constant threat of rats and mice to their grain. Stable isotope analysis indicates that the many rats and mice whose remains were found fed on the millet, but in turn they were preyed upon by the cats. The cats were within the modern size range, suggesting that they were domesticated although China lies well beyond the geographical range of the Near Eastern Wildcat. The discovery opened up the possibility that domesticated cats had made their way eastwards from Southwest Asia, or that the Quanhucun cats were domesticated locally from an East Asian subspecies of the Old World Wildcat.

It now turns out that neither was the case. An assessment of the remains by another group of researchers has found that the Quanhucun cats were not domesticated Near Eastern Wildcats but leopard cats (Prionailurus bengalensis), a small wildcat native to the region. The Quanhucun cats seem to have been a domestication of a completely different species of wildcat, but it was evidently not successful in the long term. Domesticated Near Eastern Wildcats reached China around 500 BC, and it is from these that all present-day Chinese cats are descended.

1.  Vigne, J. et al., Earliest “Domestic” Cats in China Identified as Leopard Cat (Prionailurus bengalensis). PLoS One 11 (1) (2016).
2.  Hu, Y. et al., Earliest evidence for commensal processes of cat domestication. PNAS 111 (1), 116-120 (2014).x

Friday, 22 January 2016

Death at Lake Turkana

Evidence of inter-group violence between East African hunter-gatherers 10,000 years ago

Inter-group violence has long played a part in human affairs, but just how long is unclear. Over the last thirty years, evidence has accumulated that massacres were a frequent occurrence in Neolithic Europe. Mass graves have been found at a number of sites associated with the Linearbandkeramik (LBK) culture dating to around 5,000 BC. In all cases, the victims appeared to have been attacked and killed with weapons associated with farming groups suggesting internecine conflict between LBK groups rather than attacks by local hunter-gatherers.

Evidence has now emerged of much earlier inter-group violence involving hunter-gatherers at Nataruk, west of Lake Turkana, Kenya. At the time in question, the lake extended around 30 km (18 miles) beyond its present limits and Nataruk would have been located near its western margins.

In 2012, the remains of at least 27 individuals were discovered, partly or completely exposed upon the surface of a gravel bar ridge. Most were found fully exposed and fragmented, surviving in varying states of preservation and erosion; 12 individuals were partly preserved articulated in situ. Among these, no burial pit was identified, and no preferred orientation or position of head, face, or body was noted. The total number of individuals at the site is unknown, as only those partly exposed were excavated. The remains included 21 adults (8 men, 8 women, the others of unknown sex) and 6 children. One of the women was in the third trimester of pregnancy.

Excavations also revealed stone tools similar to other Later Stone Age assemblages in the area; and fragments of bone harpoons typical of Early Holocene hunter-fishers of Lake Turkana. The skeletal remains lacked collagen so radiocarbon dates were obtained from associated sediments and shells, and an optically stimulated luminescent date was obtained from lake sediments. Based on these, it was estimated that the Nataruk human remains dated to between 9,500 and 10,500 years ago; consistent with dates obtained for shells, harpoons, and charcoal from sites in the immediate vicinity, and corresponding to a period of early Holocene high water levels in Lake Turkana.

10 of the 12 skeletons found in situ show evidence of major trauma that would have proved fatal in the immediate-to-short term, including five or possibly six cases of head and/or neck probably caused by arrows; five cases of head injury inflicted by a blunt instrument; two cases of knee fracture; two cases of multiple fractures to the right hand; and once case of fractured ribs. Only two of these skeletons show no obvious injury. Four of the skeletons, including both that lacked injuries may have been bound hand and possibly foot at time of death. Three artefacts were found within or embedded in two of the bodies: an obsidian bladelet embedded in a male skull; and a chert lunate and obsidian trapeze, found inside the pelvic and thoracic cavities of a male skeleton. Both the injuries and the embedded projectile points are considered to be diagnostic of inter-group conflict, although there was no evidence of scalping or other trophy-taking, which often observed in prehistoric warfare.

West Turkana at this time supported a substantial hunter-gatherer population. The Nataruk massacre might have resulted from a raid for territory, women, children and stored food. The pursuit of these resources would in later agricultural times make violent attacks upon settlements and the need to defend against these an ever present fact of life. Alternatively, it might have been a simple antagonistic response as two groups came into contact.
n either case, the deaths at Nataruk are a depressing testimony to the antiquity of inter-group violence and warfare.

Lahr, M. et al., Inter-group violence among early Holocene hunter-gatherers of West Turkana.; Kenya. Nature 529, 394-398 (2016).

Friday, 15 January 2016

Humans were in the Arctic 45,000 years ago

Evidence for a human presence inside the Arctic Circle 15,000 years earlier than previously believed

In 2012, archaeologists recovered the remains of a woolly mammoth from frozen sediment on a coastal bluff on the eastern shore of Yenisei Bay, 1.8 km (1.1 miles) north of the Sopochnaya Karga weather station, at 71°54′19.2″N 82°4′23.5″E. The mammoth had clearly been killed by humans, and radiocarbon dating has established that the remains are 45,000 years old.
Previously, the earliest evidence for a human presence inside the Arctic Circle is the Yana Rhinoceros Horn site on the Lower Yana River at 71°N. Artefacts recovered at this site include spear shafts made from rhinoceros and mammoth horn, and a variety of stone tools. The site dates to around 30,000 years ago.

However, the Sopochnaya Karga evidence suggests that humans had mastered the challenging conditions of the Arctic well before this date. Damage and injuries to the mammoth’s ribs, shoulder blades, tusks and lower jawbone were consistent with it having been attacked and killed with thrusting spears and light projectile weapons, and subsequently butchered.

The hunters are assumed to be modern humans, though in the absence of fossil evidence this cannot be confirmed. There is fossil and ancient DNA evidence confirming that modern humans were at Ust’-Ishim in western Siberia 45,000 years ago, but this site lies well to the south at 57°N.

Pitulko, V. et al., Early human presence in the Arctic: Evidence from 45,000-year-old mammoth remains. Science 351 (6270), 260-263 (2016).x

Thursday, 14 January 2016

RIP David Bowie

The scene at the David Bowie mural in Brixton a few days after the shock news of the legendary musician's death.

Friday, 8 January 2016

‘Iceman’ stomach bug points to more complex picture of early European settlement

Researchers obtain genome of Helicobacter pylori from 5,000-year-old stomach contents

The stomach bacterium Helicobacter pylori is found in roughly half of the world’s present-day population, although it causes symptoms in only around 10 to 15 percent of cases. The bacterium’s association with humans is very ancient, possibly originating in East Africa 58,000 years ago. Since then, various strains have emerged as humans dispersed around the world. Thus differing strains reflect differing geographical origins and are informative about past human migrations.

The European strain hpEurope is believed to have resulted from hybridization between two ancestral strains known as AE1 and AE2. It is thought that AE1 emerged in Central Asia and later evolved into the present-day strain hpAsia2. AE2 is thought to have arisen in Northeast Africa. The two strains have been thought to have hybridized in Southwest Asia 50,000 years ago, with the recombined strain arriving in Europe when populations expanded after the Last Glacial Maximum.

To test this model, researchers obtained a genome of the bacterium from the stomach contents of ‘Ötzi’, the frozen 5,000 year old corpse that was found in 1991 in the Ötztal Alps on the border between Austria and Italy. Despite the age of Ötzi’s remains, it was thought that any H. pylori present would be similar to the present-day hpEurope strain.

Instead, it turned out that Ötzi was carrying a strain that most closely resembled hpAsia2, which is rare in modern Europeans. This suggests that the hybridisation with the African H. pylori strain actually occurred more recently than 5,000 years ago, in turn implying that there was a Chalcolithic migration from Africa. The study presents interesting evidence that the history of human settlement of Europe during this period is more complex than previously believed.

Maixner, F., Krause-Kyora, B., Turaev, D., Herbig, A. & Hoopmann, M., The 5300-year-old Helicobacter pylori genome of the Iceman. Science 351 (6269), 162-165 (2016).