Paranthropus - The Earliest Tool Makers?

Who Made The First Stone Tools, And What Did They Eat?

The earliest phase of prehistory is a mess. A thick fog-of-war full of numerous hominin species, none of which can be genetically analysed and are often just crumbling fragments or portions of skulls and teeth. The surest guide we have is the ever faithful stone tool, which represents the most crude and basic approach to lithic production, named the ‘Oldowan industry’, after Olduvai Gorge in Tanzania. Of course, other species make use of tools, including those made of stone - capuchin tools can be confused for early human tools, and some researchers have even identified a ‘Chimpanzee Stone Age’ around Côte d'Ivoire. Primates making tools does of course raise questions about how we identify those made by early humans, rather than other branches of the family tree. A 2021 paper embarrassingly reported that horses and donkeys can unintentionally create stone tools just through the action of their hooves:

we show that equids can sometimes also produce equally complex cores with conchoidal breakages that exhibit the characteristics of intentionally-flaked hominin artefacts by bipolar technique and methods. As a result, sharp edged flakes with percussion platforms, previous scars and bulbs, which can easily be mistaken with hominin-made flakes, are also produced by equid self-trimming. Given the ubiquitous presence of equids in landscapes inhabited by hominins, this imposes caution when interpreting isolated flaked rocks and urges some degree of revision of the criteria to identify strictly hominin-made tools.

Given these qualifications it is no surprise that a huge cloud of uncertainty hangs over everything in this field - which hominin species is the direct ancestor of Homo sapiens? Which species made the first stone tools? Did our earliest forebears eat meat or just plants? Could these archaic people talk to one another? The questions never end.

Resolving the problem of how the Homo genus arose is one of the biggest and most difficult questions across all the sciences. We can narrow down the primate family into four categories: the New World monkeys, the Old World monkeys, the Great Apes and the strange Prosimians (lemurs, tarsiers etc). The Great Apes can be, very simply, subdivided again into chimps (Pan), gorillas, orangutans (Pongo) and ‘humans’ (Homo), which itself contains all our weird and wonderful ancestors. The human-chimp split was the last of this group, and exactly when and how it occurred is still debated. One semi-plausible scenario holds that the ancestors of humans, chimps and gorillas were separated into three regions by the Zaire River and the Rift Valley, perhaps 7-10 million years ago. I’m not including the Asian branches of the primate family here, those mysteries will need another article.

This new family branch immediately produces some fascinating species - around 7 million years ago we get Sahelanthropus tchadensis, then at 6 million we see Orrorin tugenensis, around 5 million Ardipithecus ramidus, and at 4 million Austrolopithecus arrives. The Austrolopithecines are assumed to be the ancestral species to our own, specifically Australopithecus afarensis. These guys leave fossilised tracks and appear to be the first ‘toolmakers’, creating the first ‘pebble choppers’ and mastering the techniques of striking a core to produce a deliberate flake of stone.

But like all these species, the boundaries and names are relatively arbitrary, and researchers are constantly re-defining the groups and how they can be classified. If you work in the field you’ll know that the tendency is either towards ‘lumping’ or ‘splitting’ - lumping different fossils together under one name, or splitting different fossils into new species. One such debated group is Paranthropus.

Paranthropus is an outlier in an already crowded field. A robust creature, somewhere between a gorilla and a human, with extremely powerful jaws. The muscles for grinding dense foods were connected to a crest on their skull for extra power, and they likely combined walking upright with the ability to climb. Three identified sub-species existed: P. aethiopicus, P. boisei and P. robustus, spread out from east to south Africa. The huge jaws of Paranthropus have typically coloured every interpretation of their diet, pushing them towards a grinding-chewing plant eater. Something like a migratory leaf, bulb, root and fruit eater, complemented with honey and insects, has been the general impression. But the reason to write this article is a new paper from Science which potentially changes much about what we know of Paranthropus.

Paranthropus jaws on the left, compared to a modern human

The paper, entitled Expanded geographic distribution and dietary strategies of the earliest Oldowan hominins and Paranthropus, was published in early February this year in Science. The authors present findings from excavations at Nyayanga, Kenya, many of which are remarkable. In summary:

• Oldowan stone tools were found in contexts dating to 3.032 to 2.581 million years ago.

• 1776 bones were recovered in good condition. Two hippos display evidence for butchery, in some cases with the stone tools associated and even touching the bones.

• Teeth from a Paranthropus species were found in close association with the tools and butchered bones.

• Use-wear analysis of the tools revealed evidence for both plant pounding/grinding and butchering animal remains.

The behaviors preserved at Nyayanga are at least 600,000 years older than prior evidence of megafaunal carcass and plant processing and substantially predate the increase in absolute brain size documented in the genus Homo after 2 Ma (24). The late Pliocene expanded geography of the earliest Oldowan, and new evidence of its use in diverse tasks amplifies our understanding of the adaptive advantage of early stone technology in hominin diet and foraging ecology.

What this means is that, if these results are accurate, the Oldowan stone tool industry was not confined to Ethiopa’s Afar Triangle as often believed. It also means that Paranthropus ate a much wider diet and potentially had the capacity to produce stone tools, maybe even the earliest.

There are qualifications of course, and other ‘firsts’ have been published before. In 2015 a paper announcing an Oldowan site dating back 3.3 million years seemed to place Kenya again as ground-zero for the industry, and Kenyanthropus platyops as the suspected manufacturer. But in 2016 a response paper raised questions about the evidence and conclusions drawn. Suggestions that Paranthropus might have been the original tool-maker also date back decades, such as from this 1991 paper Who Made the Oldowan Tools? Fossil Evidence for Tool Behavior in Plio-Pleistocene Hominids:

The most parsimonious interpretation of all present evidence, including geochronological, archaeological, and diagnostic fossil evidence of the hands of Australopithecus spp., Paranthropus robustus, and Homo habilis, indicates that Paranthropus and Homo habilis were both early toolmakers. Paranthropus may have been the first maker of stone tools, and these "robust" australopithecines may have relied heavily on lithic and bone technology to procure (and process) plant foods.

A quick divergence into plant biology - photosynthesis can be split into two main phases, the ‘light’ and ‘dark’ reactions. During the dark period, the plant uses the energy captured from light to create sugars. It does this by converting carbon dioxide from the air into a 3-carbon sugar, in a process called the Calvin cycle. At least, 95% of all plants do this. The remainder use a different process, which ends up with a 4-carbon sugar. These are called C3 and C4 plants respectively.

Why this is important is because C4 plants are a very particular group, which contains grasses. C4 plants take up more carbon than C3, which means they have a different ratio of the carbon-13 isotope. Animals which feed on C4 foods are therefore identifiable through isotope analysis of their remains. In the story of early humans this is important, since around 3.5 million years ago the isotopic evidence shows a shift from a predominantly C3 to a more C4 enriched diet. Paranthropus has long been presented as an example of a C4 specialist, moving to grasslands and more open, temperate environments to exploit those plants. But we now have the possibility in front of us that meat played an important role in their diet, meat from animals which fed on C4 plants. It is therefore possible that some of this C4 enriched signature came from animal, rather than plant foods.

The results from Nyayanga confirm that both plants and meat were prepared by Paranthropus using stone tools, so we’re not ruling out that they ate a lot of fibrous plant material. But we must now expand our range of habitat, species and diets away from earlier assumptions. Other hominin species, in other places, were using stone tools to eat an omnivorous diet. Given that Paranthropus is likely not a direct ancestor to modern humans, we can’t claim that meat and tool use were the reasons for our success.

Lots of questions remain - did Paranthropus simply steal or scavenge the tools? Did they hunt or stumble upon the hippos? How widespread and how old was the Oldowan industry? Who else could have been using that toolkit?

I’ve always been a believer that apparent revolutions in human development are always older than they appear - fire, hunting, tools, language and so on. My hunch is that we’ll see both the Oldowan tools and meat eating pushed back further in time in the coming years.