An earlier origin for stone tool making: implications for cognitive evolution and the transition to Homo

Abstract

The discovery of the earliest known stone tools at Lomekwi 3 (LOM3) from West Turkana, Kenya, dated to 3.3 Ma, raises new questions about the mode and tempo of key adaptations in the hominin lineage. The LOM3 tools date to before the earliest known fossils attributed to Homo at 2.8 Ma. They were made and deposited in a more C3 environment than were the earliest Oldowan tools at 2.6 Ma. Their discovery leads to renewed investigation on the timing of the emergence of human-like manipulative capabilities in early hominins and implications for reconstructing cognition. The LOM3 artefacts form part of an emerging paradigm shift in palaeoanthropology, in which: tool-use and tool-making behaviours are not limited to the genus Homo; cranial, post-cranial and behavioural diversity in early Homo is much wider than previously thought; and these evolutionary changes may not have been direct adaptations to living in savannah grassland environments.This article is part of the themed issue 'Major transitions in human evolution'.

Keywords: Homo; Lomekwi 3; Pliocene; Turkana; cognition; stone tools.

Figure 1.

Photos from the LOM3 excavation in July 2014. (a) Overview showing several artefacts being uncovered in situ. (b) Two large cores and a flake in situ in association with a fossil hippo tooth. (c) Mid-sized mammal vertebrae in situ in anatomical connection. (Online version in colour.)

Figure 2.

Photos from the LOM3 excavation in July 2015. (a) Overview showing opening of squares beneath 3 m of sterile Pliocene overburden. (b) Discovery of large core in situ. (c) Close-up of core from b showing knapping scars and fresh condition. (Online version in colour.)

Figure 3.

Progression of the LOM3 excavation since 2012. (a) Overview showing site towards the end of the 2012 season. (b) View of the excavation from above in July 2015 showing in situ level with new artefacts uncovered. (c) Close-up of artefacts uncovered from b. (d) Overview showing site at the end of the 2015 season. (Online version in colour.)

Figure 4.

In situ core (LOM3-2011-I16-3, 1.85 kg) and refitting surface flake (LOM3-2011 surf NW7, 650 g). Unifacial core, passive hammer and bipolar technique. Both the core and flake display a series of dispersed percussion marks on cortex showing that percussive activities occurred before the removal of the flake, potentially indicating the block was used for different purposes. (Online version in colour.)

Figure 5.

In situ unifacial core (LOM3-2012-H18-1, 3.45 kg), bipolar technique. (Online version in colour.)