Researchers at the Max Planck Institute for Evolutionary Anthropology in Germany have uncovered findings showing that the stone tools used by modern macaques bear a striking resemblance to tools crafted by the early human ancestors. Published insights from scientists in Science Advances describe how these primates engage with hard materials in ways that echo the deliberate shaping of stones seen in ancient sites. This discovery challenges assumptions about which species engage in tool making and what counts as an indicator of cognitive planning in the animal kingdom.
Traditionally, tool making is associated with great apes and humans, including chimpanzees, gorillas, orangutans, and gibbons. The new work notes that macaques, while more distant relatives of humans, demonstrate a capacity for using external objects to achieve practical goals. Although macaques are not considered close kin of humans, the study reveals that their behavioral repertoire includes structured, repeatable actions aimed at overcoming physical obstacles. This finding invites a reevaluation of the cognitive underpinnings of tool use across primate lineages and suggests that the roots of intentional tool making may be more widespread than previously thought.
In natural settings, crab-eating macaques frequently manipulate stones to access food resources such as nuts, shellfish, and other hard-shelled items. The observed behavior involves selecting a suitable stone, placing the target item on a firm surface, and delivering a controlled strike with a second tool. The resulting impact sometimes breaks the shell or shellfish, enabling consumption. Researchers describe these actions as practical experiments driven by immediate functional outcomes, rather than mere play. The repetitive pattern of these strikes indicates a degree of planning and consistency in technique that parallels early human exploitation of stone fractures for food processing.
The investigative team analyzed discarded tool fragments produced by macaques and compared their shapes to stone flakes recovered from ancient East African settlements associated with early humans. They found notable similarities in form, edge sharpness, and wear patterns. While the contexts differ markedly, the physical characteristics of the macaque-imposed marks resemble those of deliberately struck stones from early sites. Scientists caution that resemblance in appearance does not prove identical cognitive processes, but it does raise the possibility that macaques engage in structured stone manipulation with consequences similar to those achieved by early humans. These parallels provide a tangible link that can help illuminate the pathways by which animal behavior may have evolved toward more complex tool making.
The researchers emphasize that such patterns do not imply that macaques are direct ancestors of humans. Rather, they reflect convergent problem-solving strategies that could arise in distinct lineages facing similar ecological challenges. The broader implication is that the emergence of tool-making behaviors might have deeper roots in primate cognition than previously assumed. If stone-use practices in macaques and early human groups share common features, scientists can explore how learning, innovation, and cultural transmission might operate across species. This perspective opens new avenues for investigating the gradual development of tool technology within shared ecological niches, offering a richer picture of human evolution through the lens of comparative primatology. [citation: Max Planck Institute for Evolutionary Anthropology, study authors, Science Advances]
Taken together, the evidence suggests a continuum in which nonhuman primates display increasingly sophisticated interactions with their environment, including the systematic use of stones to modify other objects. Such behavior demonstrates not only dexterity but a capacity to extract functional value from materials found in the world. For evolutionary anthropology, these observations fuel ongoing discussions about the timeline and drivers of technological innovation, including whether deliberate tool shaping is a uniquely human hallmark or part of a broader primate cognitive toolkit. The study encourages further cross-species research to map how tool-related behaviors emerge, stabilize, and potentially spread through social learning. In the end, the work contributes to a more nuanced understanding of how our earliest ancestors may have stood on the shoulders of a wider array of intelligent primates, sharing common strategies that later evolved into the robust and diverse tool cultures seen across human societies. [citation needed]