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:
x

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:
x

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:

x
1.

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


Thursday, 21 May 2015

Earliest stone tools found in Kenya

3.3-million-year-old tool tradition significantly predates first humans

In recent years, a growing body of evidence has suggested that the making of stone tools predates the emergence of the earliest humans. In the 1990s, Oldowan-type tools dating to around 2.6 million years ago were found at the Gona River study area in Ethiopia. The tools slightly predated the then-earliest known humans, but as they were not associated with hominin remains there was no way of telling who the toolmakers had been. Towards the end of the decade, evidence of carcass butchery dating to around 2.5 million years ago was found at the nearby Bouri Formation. Bones of large mammals with cut-marks thought to be made by stone tools in the process of de-fleshing the carcasses were associated with australopithecine remains. Unfortunately, on this occasion, no actual stone tools were found.

Similarly, in 2010, it was claimed that animal bones from Dikika, Ethiopia, show cut-marks resulting from de-fleshing, and signs of having been struck with hammerstones to extract bone marrow. The remains are 3.39 million years old, early enough to preclude human involvement – but again no actual tools were found. It could not be ruled out that naturally-occurring sharp pieces of stone had been used. It is also possible that as the bones were buried in coarse-grained, sandy deposits, trampling by animals could have produced the marks. Taken as a whole, these finds made a good case for australopithecine tool making, but did not settle matters beyond reasonable doubt. Conclusive evidence was still lacking.

Such evidence has now been reported from the Kenya site of Lomekwi 3, just west of Lake Turkana. More than one hundred stone artefacts have been recovered, and at 3.3 million years old they predate even the recently-reported LD 350-1 human jawbone by half a million years. The artefacts include flakes and the cores from which they were struck. It has been shown that the cores were rotated as successive flakes were struck off, confirming that the flaking was intentional and not the result of accidental fracturing. Researchers have also managed to ‘refit’ one of the flakes back to the core from which it was struck. The tools are larger and heavier than typical Oldowan artefacts, and methods by which flakes were struck from cores was less effective. It is suggested that they represent a technology intermediate between the use of stone tools for pounding and hammering and the more flake-orientated Oldowan.

This pre-Oldowan technology has been named Lomekwian and is the final proof that hominins contemporary with Australopithecus afarensis (‘Lucy’s’ people) were making stone tools.

Reference:
Harmand, S.
et al., 3.3-million-year-old stone tools from Lomekwi 3, West Turkana, Kenya. Nature 521, 310-315 (2015).