Stone tools go even further back

Shortly after it seemed that the maker of the earliest stone tools (2.6 Ma) may have been Australopithecus africanus, thanks to a novel means of analyzing what hominin hands may have been capable of, some actual tools have turned up from even earlier times (Harmand, S. and 20 others 2015. 3.3-million-year-old stone tools from Lomekwi 3, West Turkana, Kenya. Nature, v. 521, p. 310-315). Their age is comparable with that (3.4 Ma) of animal bones from Dikika, Ethiopia showing cut marks and signs of deliberate breaking, which had previously been controversial as they suggested that local Australopithecus afarensis of a similar age had made them. What the authors claim to be ‘a new beginning to the known archaeological record’ almost a million years earlier than the first appearance of Homo fossils in the Lake Turkana area seems to point in that direction. But A. afarensis has not been found in that area, although a hominin known as Kenyanthropus platyops with roughly the same age as the tools has.

Australopithecus afarensis reconstruction
Reconstruction of Australopithecus afarensis (Photo credit: Wikipedia)

Almost 150 fine-grained basaltic artefacts turned up at the Lomekwi site, which may have been where knappers habitually worked as many of them were fragments or debitage. The cores from which flakes had been struck are large, weighing on average 3.1 kg. It seems that the tool makers may have been forcefully pounding out edged tools for a variety of uses, unlike the single-use hammer stones used by chimpanzees today. Compared with the well known Oldowan tools, however, these are cruder and made by a different knapping technique that seems not to have focused on exploiting the conchoidal fracturing that produces the sharpest tools and is a feature of the later Oldowan tools.

English: Chopper: one of the earliest examples...
Oldowan ‘chopper’ from Melka Kunture, Ethiopia. (credit: Wikipedia)

Frederick Engels, whose 1876 essay The Part played by Labour in the Transition from Ape to Man was among the first works to take Darwin’s ideas on human origins forward, would have had a field day with the new evidence. For him the vital step was freeing of the hands by a habitual bipedal gait and their manipulation of objects – together with changes to the hands that would arise by such a habit. What the first tool maker looked like, doesn’t really matter: the potential that act conferred was paramount. Nevertheless, there is a big step between early hominins and humans, from relatively small brains to those of H. erectus that were on the way to modern human capacity. The Lomekwi tools and the improved Oldwan artefacts spanned 1.7 Ma at least before H. erectus revolutionised manufacture to produce the bi-facial Acheulian hand ‘axe’, and going beyond that took almost a million years of little change in both tools and anatomy until the emergence of archaic modern humans.

Note added 28 May 2015: Within a week palaeoanthropologists’ focus shifted to the Afar Depression in Ethiopia where a new species of hominin has emerged from Pliocene sediments dated to between 3.3 and 3.5 Ma (Haile-Selassie, Y et al. 2015. New species from Ethiopia expands Middle Pliocene hominin diversity. Nature, v. 521, p. 483-488. doi:1038/nature14448). Australopithecus deyiremeda is represented by fragments of two lower- and one upper jaw plus several other lower facial specimens. So the species is differentiated from other hominins by dentition alone, but that is unmistakably distinct from extensive data on Au. afarensis which lived within a few kilometres over the same period. Until the last 15 to 20 years it was thought that Au. afarensis was the sole hominin around in the Middle Pliocene of East and Central Africa, but now it seems there may have been as many as five, the three mentioned above, plus Au. bahrelghazali from Chad and an as yet undesignated fossilised foot from Afar. For possibly three closely related species to coexist in Afar is difficult to understand: possibly they occupied different niches in the local food web or employed different strategies (Spoor, F. 2015. The middle Pliocene gets crowded. Nature, v. 521, p. 432-433). Another question is: did they all make and use tools? For the Lomekwi tools K. platyops is a candidate, but for the cut marks on bones at Dikika in Afar there are at least two: Au. afarensis and Au. deyiremeda. So multiple tool makers living at the same time suggests some earlier originator of the ‘tradition’.

Note added 4 June 2015: Add southern Africa into the equation and there is yet more breaking news about coeval hominin diversity. US, Canadian, South African and French collaborators have finally started to resolve the achingly complex stratigraphy of the fossil-rich Sterkfontein cave deposits in South Africa by using a novel approach to estimating ages of materials’ last exposure to cosmic rays (Granger, D.E. et al. 2015. New Cosmogenic burial ages for Sterkfontein member 2 Australopithecus and Member 5 Oldowan. Nature, v. 522, p. 85-88). Specifically, they managed to date the tumbling into a deep sinkhole of a recently found, almost complete skeleton of an australopithecine. It still resembles no other some 70 years after a less complete specimen was found by Raymond Dart in the mid 1940s. It was first informally dubbed ‘Little Foot’ and then Au. prometheus and up to now has been regarded as an odd contemporary of 2.2 Ma old Au. africanus. The new dating gives an age of about 3.7 Ma: so at least 6 hominids occupied Africa in the Middle Pliocene. It is beginning to look like a previously unsuspected time of sudden diversification.

Breakthrough in human tools: the scene shifts to Africa

A means of assessing the cognitive abilities of hominins is through the objects that they created, whether tools or artefacts with apparent symbolic significance. The latter include pigments, coloured shells, beads, artwork or even deliberately parallel and crossing lines gouged on otherwise innocuous rock. Undoubtedly valuable to their creators, possibly treasured and passed on until lost or broken – most are fragile – symbolic artefacts are rare. So although they shout ‘thoughtful’, their age tells us little about when such a capacity first arose. Many archaeologists and palaeoanthropologists assert that creating and/or manipulating symbols may signify a link with being able to speak. Tools are a lot easier to find, probably as discards and lost items, and a well-described and understood sequence of forms and sometimes uses has been established, which extends as far back as perhaps 3 Ma – before the genus Homo appeared.

In terms of their meaning in terms of the consciousness of their makers and users, there are possibly four major recognisable steps. Chimpanzees and some birds can learn to pick up natural objects, such as stones and twigs, and use them: some bands of chimps even retain the knowledge. A step beyond that is preparing a natural object for use, as with breaking a pebble to create a cutting edge: something not exclusively human because it is possible that pre-human hominins created the earliest such Oldowan tools. Being able to visualise hidden potential inside something natural is altogether more advanced, and is represented by the iconic bi-face or Acheulean ‘hand-axe’. Its earliest makers, H. ergaster and erectus, literally brought such objects to light by skilfully knapping away the outer parts of substantial lumps of suitable rock. The knowledge endured for more than a million years but was eventually added to and superseded by a range of more delicate and specific stone tools, but more sophisticated tools represented the same ‘liberation’ of a simple idea held in rock. The fourth general cognitive leap was to add several resources together as composite tools, and arguably we have not long emerged from that phase with the creation of composite tools that help us design and make other tools: a machine-tool culture.

English: Backed edge bladelet Español: Hojita ...
Example of a microlith (credit: Wikipedia)

It is that penultimate step-up in consciousness that has been engaging archaeologists since they first realised that some small, sharp chips of stone were not waste but deliberately crafted for combination with wood or bone. Such ‘microliths’ have been found in intact arrows and sickles of the Meso- and Neolithic, but their range steadily goes back in time with more research. Unmistakeable microliths have now been discovered at the South African coastal site at Pinnacle Point, in an occupation layer that is 71 ka old (Brown, K.S. and 8 others 2012. An early and enduring advanced technology originating 71, 000 years ago in South Africa. Nature, v. 491, p. 590-593).

The Pinnacle Point technology was indeed sophisticated, microlith manufacture requiring fire treatment as well as choice of rock and careful shaping and sharpening. As well as extending the microlith culture back so far the team of South African, US, Australian and Greek archaeologists compared them with 28 later African tool kits. The designs have barely changed from 71 ka to those of the last few hundred years. Kyle Brown and colleagues show that the industrial method endured, thereby laying to rest the somewhat reactionary notion that the methods were lost again and again in Africa after separate inventions and were only taken up decisively by the supposed ‘advanced’ anatomically modern humans who colonised Europe…

It is difficult to see how the Pinnacle Point microliths could have been useful, unless hafted in arrows or throwing sticks – maybe even saws and sickles? Crucially, they predate larger blade-tools that could have been hafted to form spears. The focus must now shift to the Zambian scene where possible microliths are reported at two 250 ka sites. If confirmed, they would link the decisive fourth cognitive step towards humanity with the very origin of fully modern humans, rather than a much later, non-African dawning of ‘smarts’ along with language, advanced art and much else in the chilly caves of southern Europe.

Of all human-colonised continents Africa lags far behind the rest as regards spread and density of archaeological digs. Only the ‘famous’ sites attract resources for investigation. Imagine what might emerge once there are more local people with research skills, equipment and transport; and, dare I say it, more independence of action and the attendant confidence in their ability.