🛠️ This discovery of 2.75 million-year-old tools upends what we knew about humans

The eastern shore of Lake Turkana in Kenya holds the memory of one of the oldest examples of technological transmission. At this site called Namorotukunan, stone tools tell a much longer story than expected, spanning several hundred thousand years.

The unearthed artifacts, modified cobbles and sharp flakes characteristic of the Oldowan, form a remarkable archaeological sequence. Their presence is attested in three distinct geological layers, dated respectively to 2.75, 2.58 and 2.44 million years ago. This repetition indicates an uninterrupted transmission of know-how, rather than mere isolated episodes of manufacture. The technical consistency observed over such a long period reveals a cultural tradition already firmly established.

Technical mastery anchored in time

Detailed analysis of over 1200 tools has revealed a rigorous selection of raw materials. Hominins favored fine-grained rocks like chalcedony, whose predictable fracture allowed for obtaining sharp and durable cutting edges. This anticipation in material choice demonstrates an intuitive understanding of stone properties, a form of applied geological competence. The standardization of knapping methods indicates social learning, essential for preserving knowledge over thousands of generations.

The function of these tools has been clarified by the study of use-wear traces and residues. They constituted a veritable multipurpose toolkit, used for cutting animal carcasses and processing plant materials. The discovery of cut marks on fossil bones associated with the tools confirms the broadening of the dietary regime. Access to meat, made possible by this technology, represented a decisive nutritional advantage for these populations.

The longevity of this lithic industry contrasts with the idea of sporadic and quickly forgotten innovations. It sketches a portrait of groups capable of a form of consistency in technical gesture, despite a changing environment. This cultural stability, over such a vast period, suggests that the ability to create, use and transmit technology is a characteristic much older than commonly believed.

A changing landscape and technological adaptation

The environmental context of this period has been reconstructed using a range of geochemical and sedimentological methods. Researchers analyzed volcanic ashes, magnetic signals trapped in sediments, and plant microfossils. The landscape of the Turkana basin underwent profound transformations, oscillating between wet phases and episodes of strong aridity, marked by the expansion of savannas and grasslands prone to fires.

Faced with this climatic instability, the response of hominins was not biological, but technological. While vegetation and resources changed radically, their tool-making method remained unchanged. This resilience through tools allowed them to adapt without having to develop new physical abilities. Technology served as a buffer against environmental hazards, guaranteeing reliable access to food.

This discovery significantly pushes back the date for the emergence of a continuous technological tradition. It indicates that hominins with still modest brain sizes, predating the appearance of the genus Homo, already mastered elaborate cognitive and social skills. The manufacture and sustained use of tools therefore appear to have been a very early key factor in the human evolutionary trajectory, long before the brain expansion often considered its trigger.