Weapons Technology Powered Human Evolution

Thomas Hobbes’s uncomfortable view of human nature looks remarkably prescient in the light of new discoveries in Kenya. Back in the mid 17th century—before anyone had any inkling of deep time or the destabilization of essential identity that would be brought about by an understanding of the facts of human evolution (i.e. before the idea was possible that nature was mutable)—Hobbes argued that we were fundamentally beastly (selfish, greedy, cruel) and, in the absence of certain historically-developed and carefully nurtured institutional structures, would regress to live in a state of nature, in turn understood as a state of perpetual war.

We can assume that John Frere would have agreed with Hobbes. Frere, we may read (and here Wikipedia is orthodox, typical and, in a critical sense, wrong), “was an English antiquary and a pioneering discoverer of Old Stone Age or Lower Paleolithic tools in association with large extinct animals at Hoxne, Suffolk in 1797.” In fact, while Frere did indeed make the first well-justified claim for a deep-time dimension to what he carefully recorded in situ, saying that the worked flints he found dated to a “very remote period indeed,” he did not think they were tools in any neutral sense, stating that the objects were “evidently weapons of war, fabricated and used by a people who had not the use of metals.”

Frere’s sharp-edged weapons can now be dated to Oxygen Isotope Stage 11—in other words, to a period lying between 427 and 364 thousand years ago—and even he might have been surprised to learn that the people responsible were not modern humans, but a species, Homo erectus, whose transitional anatomy would first come to light through fossil discoveries in Java a century later. Subsequent archaeological and palaeoanthropological work (significant aspects of it pioneered by Frere’s direct descendant, Mary Leakey) has pushed the story of genus Homo back ever further, revealing as many as a dozen distinct species (the number varies with the criteria used).

Alongside the biological changes runs a history, or prehistory, of technology. It has usually been supposed that this technology, surviving mainly as modified stone artifacts, was a product of the higher brain power that our human ancestors displayed. According to Darwin’s sexual selection hypothesis, female hominins favored innovative male hunters, and the incremental growth in intelligence led, ultimately, to material innovation (hence the evocative but not taxonomic term, Homo faberMan the Maker).

So powerful was this idea that, although chipped stone artifacts dating to around 2.6 million years ago have been known for some time, there was a strong presumption that genus Homo had to be involved. This is despite the fact that the earliest fossils with brains big enough to be classified in this genus dated at least half a million years later. It was a fairly general hunch within palaeoanthropology that the genus Homo populations responsible for early chipped-stone technologies had simply not yet been discovered. Those few of us who, grounded in the related field of theoretical archaeology, thought differently, remained reliant on a very broad kind of consilience to counter this ex silencio assumption.

So to me it was wonderful news when, in May 2015, Sonia Harmand and co-workers published an article in Nature entitled “3.3-million-year-old stone tools from Lomekwi 3, West Turkana, Kenya,” because the strata at their site date to a period when no one seriously doubts that australopithecines, with their chimp-sized brains, were the smartest of the savannah-dwelling hominins. The discovery shows unambiguously that technology preceded, by more than one million years, the expansion of the cranium that is traditionally associated with the emergence of genus Homo.

Harmand et al follow current convention in naming their artifacts tools, rather than offensive weapons. This apparently more neutral terminology is, I think, a reflex of our continual and pervasive denial of Hobbes’s truth. Hobbes obviously did not have the information available to understand the time-depths or the bio-taxonomic and evolutionary issues involved, but had he known about Lomekwi 3 he would probably have called it differently, as Frere subsequently did at Hoxne.

The pre-human emergence of weapons technology makes functional and evolutionary sense. We are not talking about choosing appropriate twigs for the efficient extraction of termites, or the leaves best suited to carrying water, but about the painstaking modification of fine-grained igneous rocks into sharp-edged or bladed forms whose principal job was to part flesh from flesh and bone from bone.

If the word hunting helps gloss the reality of what such sharp stone artifacts were used for, then we can reflect on the type of hunting recently documented from the Aurora stratum at the site of Gran Dolina (Atapuerca), Spain. Here, Palmira Saladie Balleste and co-workers recently reported (Journal of Human Evolution, 2012) on a group of Homo antecessor (or, arguably, erectus) who fed on individuals from, presumably, a rival group. The age profile of the victims was “similar to the age profiles seen in cannibalism associated with intergroup aggression in chimpanzees,” that is, those eaten were infants and immature individuals.

That much of the data on early, systematic, endemic violence in our deeper (and shallower) prehistory comes as a surprise is due to the pervasive myth about the small-scale band societies of the archaeological past having somehow been egalitarian. This idea has an odd genealogy that probably goes back to the utopian dreaming of Hobbes’s would-be intellectual nemesis, Jean-Jacques Rousseau, with his ideas of harmony and purity in nature, and his belief that the savage state of humanity was noble rather than decadent.

Rousseau, like Hobbes, lacked the possibility of an evolutionary perspective, and also dealt in more or less essentialist assertions. But once we have to bridge from wild primate groups to early human ancestors, the tricky question of the roots of egality arises. If the chimpanzees and gorillas that can be studied in the wild have clear status hierarchies that are established, maintained and altered by force, including orchestrated murder and cannibalism, then how could fair play magically become a base-line behavior?

Somewhere along the way, it seems to have been forgotten that the 19th century founders of modern socio-cultural anthropology, Lewis Henry Morgan, Edward Burnett Tylor, and Edvard Westermarck, recorded all kinds of unfairness in indigenous North American and Pacific societies: we may not want the Tlingit and Haida, Ojibwa and Shawnee to have had slaves, for instance, but avoiding mentioning it in modern textbooks does a great disservice to the original ethnographic accounts (and the slaves).

Returning to the news from Lomekwi 3, we can now see that technology was not just a figural but a literal arms race. Reanalyzing the take-off in cranial capacity that began around 2 million years ago, we can see that blades and choppers needed to be already available to replace the missing biology—the massive ripping canines and heavy jaw muscles that previously hampered, in direct bio-mechanical terms, the expansion of the braincase. As Frere would immediately have understood, these artifacts included weapons, perhaps predominantly and pre-eminently. Only by postulating high-level competition between groups can we understand the dramatic adaptive radiation of hominin types and the fact that, ultimately, only one hominin species survived.

The paradox is that, by sharpening the first knives to extend the range of possible forms of aggression, we opened up a much broader horizon, in which technology could be used for undreamed-of purposes. Yet Hobbes’s instinct that our nature was borne of war, and Frere’s conclusion that the world’s primal technology was offensive, should not be ignored. In the artificial lulls when atavism is forced into abeyance we are happy to forget Hobbes’s admonition that it is only through the careful cultivation of institutions that stable peace is at least possible.