The Evolution of Stone Tools - Beyond Grahame Clark's Lithic Modes

The Original Human Innovation

Levallois and Bifacial Tools from Nor Geghi 1
Technological variability at Nor Geghi 1 (NG1). A) Biface with two biface resharpening/thinning flakes. B–C) Levallois cores with Levallois flakes. D) Blade core with blade. Daniel S. Adler

Making stone tools is a characteristic that archaeologists use to define what is human. Simply using an object to assist with some task indicates a progression of conscious thought, but actually making a custom tool to perform that task is the "great leap forward". The tools that survive down to today were made of stone. There may have been tools made of bone or other organic materials before the appearance of stone tools--certainly, many primates use those today--but no evidence for that survives in the archaeological record.

The oldest stone tools that we have evidence for are from the earliest sites dated to the Lower Paleolithic--which shouldn't come as a surprise since the term "Paleolithic" means "Old Stone" and the definition of the beginning of the Lower Paleolithic period is "when stone tools were first made". Those tools are believed to have been made by Homo habilis, in Africa, about 2.6 million years ago, and are typically called Oldowan Tradition.

The next major leap forward originated in Africa about 1.4 million years ago, with the Acheulean tradition of biface reduction and the famous Acheulean handaxe, spread out into the world with the movement of H. erectus.

Levallois and Stone Making

The next broad leap forward recognized in stone tool technology was the Levallois technique, a stone tool making process that involved a planned and sequenced pattern of removing stone flakes from a prepared core (called bifacial reduction sequence).

Traditionally, Levallois was considered an invention of archaic modern humans about 300,000 years ago, thought to be spread outside of Africa with the spread of humans.

However, recent investigations at the site of Nor Geghi in Armenia (Adler et al. 2014) recovered evidence for an obsidian stone tool assemblage with Levallois characteristics firmly dated to Marine Isotope Stage 9e, about 330,000-350,000 years ago, earlier than the presumed human exit from Africa.

This discovery, in combination with other similarly dated discoveries throughout Europe and Asia, suggests that the technological development of the Levallois technique was not a single invention, but rather a logical outgrowth of the well-established Acheulean biface tradition.

Grahame Clark's Lithic Modes

Scholars have wrestled with identifying a progression of stone tool technology since the "Stone Age" was first proposed by C.J. Thomsen back in the early 19th century. Cambridge archaeologist Grahame Clark, [1907-1995] came up with a workable system in 1969, when he published a progressive "mode" of tool types, a classification system that is still in use today.

  • Mode 1: Pebble cores and flake tools, early Lower Paleolithic, Chellean, Tayacian, Clactonian, Oldowan
  • Mode 2: Large bifacial cutting tools made from flakes and cores such as Acheulean handaxes, cleavers, and picks, later Lower Paleolithic, Abbevillian, Acheulean. Developed in Africa, ~1.75 million years ago and spread into Eurasia with H. erectus about 900,000 years ago.
  • Mode 3: Flake tools struck from prepared cores, with an overlapping sequence of flake removal (sometimes referred to as façonnage) system - including the Levallois technology, Middle Paleolithic, Levallois, Mousterian, arose during the Late Acheulean at the onset of the Middle Stone Age/Middle Paleolithic, about 300,000 years ago.
  • Mode 4: Punch-struck prismatic blades retouched into various specialized forms such as endscrapers, burins, backed blades and points, Upper Paleolithic, Aurignacian, Gravettian, Solutrean
  • Mode 5: Retouched microliths and other retouched components of composite tools, Later Upper Paleolithic and Mesolithic, Magdalenian, Azilian, Maglemosian, Sauveterrian, Tardenoisan

John Shea: Modes A through I

John J. Shea (2013, 2014, 2016), arguing that long-standing named stone tool industries are proving obstacles to understanding evolutionary relationships among Pleistocene hominids, has proposed a more nuanced set of lithic modes. Shea's matrix has yet to be broadly adopted, but in my opinion, it is an enlightening way to think about the progression of the complexity of stone tool making.

  • Mode A: Stone percussors; pebbles, cobbles or rock fragments which have been damaged by repeated percussion. Hammerstones, pestles, anvils
  • Mode B: Bipolar cores; rock fragments which have been broken by setting the core on a hard surface and striking it with a hammerstone
  • Mode C: Pebble cores / non-hierarchical cores; rock fragments from which flakes have been removed by percussion
  • Mode D: Retouched flakes; flakes that have had a series of cone and bending fractures removed from their edges; includes retouched cutting-edge flakes (D1), backed/truncated flakes (D2), burins (D3), and retouched microliths (D4)
  • Mode E: Elongated core tools; roughly symmetrically worked objects that are longer than wide, known as 'bifaces', and include large cutting tools (<10 cm in length) such as Acheulean handaxes and picks (E1), thinned bifaces (E2); bifacial core tools with notches such as tanged points (E3), celts (E4)
  • Mode F: Bifacial hierarchical cores; clear relationship between the first and subsequent fractures, includes preferential bifacial hierarchical cores, with at least one flake detached (F1) and recurrent, which includes façonnage stone working (F2)
  • Mode G: Unifacial hierarchical cores; with a roughly planar striking platform at a right angle to the flake release surface; including platform cores (G1) and blade cores (G2)
  • Mode H: Edge-ground tools; tools in which the edge was created by grinding and polishing, celts, knives, adzes, etc
  • Mode I: Groundstone tools; made by cycles of percussion and abrasion