Rosa Rubicondior: Refuting Creationism - Common Origins - Like Humans, Chimpanzees Use Engineering Skills to Make Tools

Tuesday, 25 March 2025

Refuting Creationism

Common Origins
Like Humans, Chimpanzees Use Engineering Skills To Make Tools

A Gombe chimpanzee using a termite fishing tool to fish termites.

Credit: Dr Alejandra Pascual-Garrido

A Gombe chimpanzee using a termite fishing tool to fish termites.

Credit: Dr Alejandra Pascual-Garrido

Research into chimpanzee ‘engineers’ has implications for understanding human technological evolution | University of Oxford

Not so long ago, it was commonly claimed that humans were exceptional due to their supposedly 'unique' ability to make and use tools. This assertion was often used to reinforce the idea that humans occupied a special position at the pinnacle of creation, justifying the biblical concept of human dominion over the rest of nature.

However, this claim was never credible to anyone observing nature carefully. It was largely promoted by religious authorities to foster a sense of human uniqueness and importance. This, in turn, reinforced belief in a creator god, supported the authority of religious institutions and their clerics, and justified their claims to the right to create laws governing human behaviour.

Scientific research has increasingly exposed the fallacy of this notion of human exceptionalism. Tool-making and tool use in humans are indeed more sophisticated than in other animals, but this ability is far from unique. Many other species demonstrate these abilities, notably chimpanzees—our closest living relatives. The widespread occurrence of tool use in nature strongly suggests this trait was present in a common ancestor we share with other primates. Furthermore, the independent evolution of tool use in species as diverse as birds, bees, and octopuses demonstrates that this capability is not unique to humans but rather a result of natural evolutionary processes.

Another human characteristic, traditionally cited by religious authorities as evidence for special creation and human exceptionalism, has, once again, been shown by science to be better explained as evidence of our evolutionary heritage within the natural world.

And today we have evidence that chimpanzees not only make and use tools but employ sophisticated 'engineering' skill in their choice of the right materials for their construction. It comes in the form of a paper published, open access, in iScience by a team of researchers led by Dr Alejandra Pascual-Garrido, of the School of Anthropology and Museum Ethnography, University of Oxford, UK.

Chimpanzees have recently been shown to carefully chose the right materials to make tools with. What information do you have on how our view of humans as the only tool makers has changed over time?

Historically, toolmaking was viewed as uniquely human—a defining hallmark separating us from all other animals. Early anthropologists often argued that humans alone possessed the intellectual capability, foresight, and planning necessary to create and use tools. However, over time, extensive research has challenged and significantly altered this perspective. Here's a summary of how the view of humans as exclusive toolmakers has evolved:

Early Views (19th and Early 20th Century)

Toolmaking was initially considered exclusive evidence of human exceptionalism.
Scholars believed only humans possessed the cognitive sophistication and manual dexterity needed for tool creation.

Jane Goodall's Groundbreaking Observations (1960s)

Jane Goodall’s pioneering work with wild chimpanzees at Gombe Stream Reserve drastically changed perceptions.
In 1960, Goodall famously observed chimpanzees modifying twigs and grasses to fish for termites—one of the first documented examples of tool use by non-human animals.
Louis Leakey famously responded, "Now we must redefine tool, redefine Man, or accept chimpanzees as human."

Expansion of Animal Tool Use (1970s–1990s)

Following Goodall’s revelations, many species were observed using and making tools:

Chimpanzees and bonobos: Use rocks as hammers to crack nuts, carefully selecting stones for size, hardness, and durability.
Orangutans: Modify leaves to use as umbrellas, water vessels, or napkins.
Capuchin monkeys: Use stones as hammer-and-anvil tools to crack open nuts and seeds, demonstrating intentional tool selection.
Birds (especially corvids): Ravens, crows, and New Caledonian crows craft hooks from twigs to extract larvae from tree trunks.

Recognition of Cultural Transmission (2000s)

Researchers realized animals don't merely use tools instinctively—they learn and pass tool-making traditions culturally, especially in chimpanzees.
Different chimpanzee groups exhibit distinct toolmaking behaviors ("cultures") passed down through generations, suggesting a previously underestimated cognitive complexity.

Deliberate Material Selection (Recent Discoveries, 2010s–2020s)

Recent studies demonstrate animals engage in sophisticated decision-making processes, carefully selecting materials based on durability, efficiency, and appropriateness for specific tasks:
Chimpanzees deliberately select certain woods or grasses depending on the desired task and anticipated outcome. They consider hardness, flexibility, length, and efficiency.
Research shows chimpanzees will travel distances specifically to collect suitable stones or sticks, demonstrating foresight and planning, once considered uniquely human.
Such evidence has led to reconsideration of toolmaking as a continuous cognitive gradient across species rather than a sharp human-animal divide.

Redefining Human Exceptionalism

Today, toolmaking is no longer regarded as a uniquely human behavior. Instead, it’s seen as part of a spectrum of cognitive abilities spread widely across the animal kingdom.
Human exceptionalism is increasingly defined in terms of degree and complexity, rather than absolute presence or absence of skills like toolmaking.
Humans' unique status may now focus on the unprecedented scale and sophistication of their technology, symbolic reasoning, cumulative cultural transmission, and the development of abstract systems (writing, mathematics, science).

In Conclusion:

Over the past six decades, our perception has evolved dramatically—from viewing humans as the sole toolmakers, to recognizing widespread animal tool use, and finally understanding the depth of planning and intentionality that many animals, notably chimpanzees, demonstrate. This shift reflects a broader move away from anthropocentric exceptionalism toward recognizing cognitive complexity across the animal world.

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Their research is the subject of an Oxford University News release:

Research into chimpanzee ‘engineers’ has implications for understanding human technological evolution
A multidisciplinary team of researchers led by Dr Alejandra Pascual-Garrido, Research Affiliate at the School of Anthropology and Museum Ethnography, University of Oxford, have discovered that chimpanzees living in Gombe Stream National Park in Tanzania employ a degree of engineering when making their tools, deliberately choosing plants that provide materials that produce more flexible tools for termite fishing.
These findings, published in the journal iScience, have important implications for understanding the technical abilities associated with the making of perishable tools – a topic which remains a highly unknown aspect of human technological evolution.

Termites are a good source of energy, fat, vitamins, minerals and protein for chimpanzees. To eat the insects, chimpanzees need to use relatively thin probes to fish the termites out of the mounds where they live. Given that the inside of the mounds is made up of winding tunnels, the team of scientists from the Max Planck Institute for Evolutionary Anthropology, the Jane Goodall Institute in Tanzania, the University of Algarve and the University of Porto in Portugal, and the University of Leipzig, hypothesized that using flexible tools would be more effective for chimpanzees at fishing out the insects than using rigid sticks.

To test this, Dr Alejandra Pascual-Garrido took a portable mechanical tester to Gombe and measured how much force it took to bend plant materials used by the apes compared to plant materials that were available but never used. Findings showed that plant species never used by chimpanzees were 175 percent more rigid than their preferred materials. Furthermore, even among plants growing near termite mounds, those that showed obvious signs of regular use by the apes produced more flexible tools than nearby plants that showed no signs of use.

This is the first comprehensive evidence that wild chimpanzees select tool materials for termite fishing based on specific mechanical properties.

Dr Alejandra Pascual-Garrido, Senior author
Primate Models for Behavioural Evolution Lab
School of Anthropology and Museum Ethnography
University of Oxford, Oxford, UK.

[Dr Alejandra Pascual-Garrido] has been studying the raw materials used in chimpanzee tools in Gombe for more than a decade.

Notably, certain plant species, such as Grewia spp., also constitute tool material for termite fishing chimpanzee communities living up to 5,000 kilometres away from Gombe, implying that the mechanics of these plant materials could be a foundation for such ubiquitous preferences, and that rudimentary engineering may be deeply rooted in chimpanzee tool-making culture.

Wild chimpanzees may therefore possess a kind of "folk physics" – an intuitive comprehension of material properties that helps them choose the best tools for the job. Their natural engineering ability is not just about using any stick or plant that is available; chimpanzees specifically select materials with mechanical properties that can make their foraging tools more effective.

This novel approach, which combines biomechanics with animal behaviour, helps us better understand the cognitive processes behind chimpanzee tool construction and how they evaluate and select materials based on functional properties.

Dr Alejandra Pascual-Garrido.

The findings raise important questions about how this knowledge is learned, maintained and transmitted across generations, for example, by young chimpanzees observing and using their mothers' tools, and whether similar mechanical principles determine chimpanzees' selection of materials for making other foraging tools, such as those used for eating ants or harvesting honey.

This finding has important implications for understanding how humans might have evolved their remarkable tool using abilities. While perishable materials like wood rarely survive in the archaeological record, the mechanical principles behind effective tool construction and use remain constant across species and time.

Adam van Casteren, lead author
Department of Human Origins
Max Planck Institute for Evolutionary Anthropology
Leipzig, Germany.

By studying how chimpanzees select materials based on specific structural and/or mechanical properties, we can better understand the physical constraints and requirements that would have applied to early human tool use. Using such a comparative functional framework provides new insights into aspects of early technology that are not preserved in the archaeological record.

Highlights

Materials used by chimpanzees for toolmaking exhibit specific physical properties
Plant species used for tools produced more flexible probes than plants never used
Construction of fishing probes suggests an understanding of material properties
Chimpanzee toolmaking mechanics may inform on the technical skills of early hominins

Summary
Physical evidence of early hominin perishable tools is scarce. However, it is reasonable to assume the mechanical constraints surrounding tool use and manufacture have remained somewhat constant. Using a functional framework to understand the technical capabilities of extant hominoid tool users presents a novel approach to predict the perishable tool-using capabilities of our earliest relatives. We investigated the structural and mechanical properties of plant materials used by wild chimpanzees to make termite fishing probes. Materials sourced from plant species extensively used by chimpanzees produced implements of greater flexibility than those constructed from plants never selected by chimpanzees. This pattern was also reflected in chimpanzee tool species preferences, with preferred plant species producing highly flexible implements. Implement flexibility aligns with functional predictions and likely facilitates termite attachment. Our findings provide insights into the technical skills associated with perishable artefact-making and raise questions about how this knowledge is learnt and culturally transmitted.
Graphical abstract

Introduction
Evidence from even the earliest lithic assemblages suggests that selecting materials based on often inconspicuous mechanical properties has been essential to human tool-using abilities.^1,2,3,4 For example, Oldowan toolmakers chose finer grained materials more likely to optimally fracture when making stone tools.^1,4 Yet, our knowledge of the evolution of toolmaking skills is incomplete, relying on an imperfect archeological record of stone tools.^5,6 Comparative data on stone tool use by extant apes and monkeys has been used as a model to fill in some of the gaps left by the archeological record, demonstrating an understanding of the general physical characteristics of the tools used and how this modulates functionality.^{7,8,9,10,11,12} However, surprisingly little has been investigated regarding the mechanical characteristics and the resulting biomechanical properties of materials used in toolmaking, with what is known remaining somewhat descriptive^{13,14,15,16,17} (but see studies by Lamon et al.¹⁸ and van Casteren et al.¹⁹). Given their toolmaking abilities,¹⁴ data from one of our closest living relatives, common chimpanzees (Pan troglodytes), are especially valuable.²⁰ This is particularly true for the crafting of perishable tools that, by their nature, are generally absent from the archeological record but still remain a significant and highly neglected aspect of technological evolution in the Primate order, including humans.^21,22,23

After humans, common chimpanzees have the most complex and varied repertoires of toolmaking behavior of all extant primate species.^24,25 While some populations use stone tools, the majority of chimpanzee tools are sourced from plants^14,26 which require an additional manufacturing step for appropriate use.²⁷ Given their close phylogenetic proximity to our lineage,²⁸ Pan troglodytes technical abilities are often compared to the tool using skills of our early ancestors.^{3,6,8,14,29,30} Chimpanzees employ tools in a wide range of contexts, including communication, grooming, self-comfort, and protection,¹⁴ with the most prevalent, complex, and diverse tools used for subsistence.^15,31 Implements are manufactured from a diverse breadth of plant materials that vary according to the task.¹⁵ The wide variety of implements and materials utilized suggests that for certain tasks some materials are better than others, and chimpanzees seem to have an advanced understanding of this.^13,14,32

In early human toolmaking, the mechanical properties of raw materials influenced elements of stone tool production, including invention, spread, and organization of technology.^1,33 Likewise, in nonhuman tool production, the mechanical properties of a tool strongly influence the design of the resulting implement and the behavior expressed while using it.^{32,34,35,36,37} Extensive research on chimpanzee tool use has shown that material selection in tool manufacture is widespread in Pan troglodytes.^13,14,38,39 However, the underlying reasons for this selectivity are not yet fully understood. One possible explanation is that chimpanzees possess a functional understanding of the structural and mechanical properties of the materials used in tool production, which influences their choices. To test this hypothesis, it is necessary to quantify the structural and mechanical properties of both the plant materials selected for tool use and those seemingly overlooked—something that, to our knowledge, has not yet been done in the context of chimpanzee tool use. In this study we investigated the structural and mechanical properties of plant materials that are chosen for the manufacture of termite fishing tools by chimpanzees living at Gombe Stream National Park, Tanzania. While it is well documented^38,40,41 that chimpanzees selectively choose specific material for toolmaking, our research focuses on investigating the underlying physical properties that may influence their choices, a research area that remains largely unexplored.

In chimpanzees, termite fishing acumen is acquired primarily through observation of mothers and maternal relatives during the early years of life,^42,43,44 with techniques used varying regionally, including between neighboring communities.^30,45,46,47 The most common technique, also used by Gombe chimpanzees, consists of the insertion of a single probe into a Macrotermes termite exit or alate hole (Video S1). Termite soldiers attack the probe with their mandibles, when the probe is withdrawn the attached insects can be easily consumed¹⁴ (Figure 1). Probing tools are manufactured from various plant materials (i.e., bark, grass, sedges, twigs, vines, etc.)^{14,40,45,46,48} sourced from species mostly located near the termite mound, but also occasionally from further away indicating some sort of planful cognitive behavior,^{38,45,49,50,51} e.g., perception, cognition, and recollection. During processing, implements are generally removed from the main stem and/or lower branches of plants, normally using teeth. The resulting tools at Gombe averaged approximately 28–30 cm (range: 7–118 cm) in length and about 2–4 mm (range: 0.1–7.6 mm) in diameter^45,46 (Figure 2A). While part of the variation in tool use techniques and construction materials can be attributed to prey characteristics and ecological context,^30,32,40,45 others are attributed to social influences that can, if maintained across generations, be termed as cultural.^{30,41,42,44,45,47,48,52}

Figure 1 The hypothesized functionality of rigid vs. flexible probes used as termite fishing tools

(B and C) When a probe is inserted into a termite mound (A) a rigid probe will likely not conform to the bends of the tunnel reducing its effectiveness (B). A more flexible probe will navigate the tunnels better and likely provide more opportunity for termite attachment (C).

Figure 2 In-situ tools used for termite fishing

Probe examples of termite fishing tools.
White arrows indicate examples of the tunnels found in Macrotermes mounds in which the probe tools are inserted.
A probe tool left inserted into a Macrotermes mound, white arrow highlights the inserted end.

Video S1. A video of a chimpanzee termite fishing with a plant tool

Chimpanzees at Gombe fish epigeal Macrotermes mounds year-round,^45,46 though efforts are concentrated during the early wet season (October to December). This timing aligns with the annual reproductive and dispersal cycle of the termites when the insects are more active and accessible. Abandoned tools are regularly recovered by researchers at fished mounds during these months, becoming scarcer during the dry season.^32,45 Chimpanzees demonstrate high selectivity regarding the plant material and species used to make their tools, with only a dozen or so species recorded as tool sources from the many more suitable and available plant species found near the termite mounds.^45,46,50 Interestingly, even within known source species, chimpanzees show preferences: some individual plants are used more frequently while others are never utilized.⁴¹ Given the wide range of inter- and intra-species variation of plant structural and mechanical properties, and that such physical properties could influence the functionality of a constructed tool, we hypothesize that the structural and mechanical properties of plant material may be a selection criterion used by chimpanzees when making their tools.

When probing with beam-like tools an effective implement needs to be flexible; capable of bending to follow the irregular twisting of the termite passages (Figure 1B and 1C; Figure 2B) yet durable enough to maintain its original shape upon withdrawal so as to be reused.^32,45 Mechanically, flexural rigidity describes the resistance of a beam,⁵³ like probing tools, to bending. It is a salient structural property, encompassing the material a tool is made from and the shape/size of the implement. Measurements of flexural rigidity will effectively quantify the flexibility of a tool. It is expected that tools with low flexural rigidity will be very flexible while tools that demonstrate a higher flexural rigidity will be stiffer and more rod-like. Flexural rigidity is defined as the product EI, where E is the Young’s or elastic modulus and I is the second moment of area.^53,54 E is essentially the stiffness of a material, its resistance to reversible deformation, measured as the stress (force per unit area) that produces a strain (a proportional change in dimensions).⁵⁵ E is a material property; this measurement informs about the material the tool is made from, not how the artifact itself behaves. I is the distribution of material around the neutral axis of a beam, essentially describing the shape and size of a tool’s cross section. The E of plant tissues can vary within an individual, between members of the same species and interspecifically. This means that plant parts that share similar morphology may behave rather differently to imposed loads, depending on the material they are made up from. The morphology of termite fishing tools is somewhat constrained by the size and shapes of the passages found in epigeal Macrotermes mounds³² (Figures 2B and 2C); therefore, it seems reasonable to assume that chimpanzees could affect the EI of the manufactured tools by choosing materials that deliver desired mechanical behaviors, such as low rigidity.

It has been previously shown in experiments with captive apes (Pan troglodytes, Pan paniscus, Pongo pygmaeus, and Gorilla gorilla) that suitable tools can be selected based on rigidity.⁵⁶ However, in these experiments levels of rigidity were not fully quantified and tools were made of unnatural materials that often presented quite stark variation in their levels of rigidity. In natural environments, the variation in the way tools behave mechanically may be much subtler and less conspicuous to the user. The ability of captive apes to select tools with the correct rigidity for a task⁵⁶ and the well-described tool material selection in wild chimpanzees^13,14,38 presents an interesting question. Are wild apes selecting plant materials for tool construction that deliver specific mechanical behaviors in their implements? If this is the case, we would expect chimpanzees to select plant material that produced tools with specific mechanical characteristics.

As stated earlier, termite fishing implements must be flexible to navigate the intricate tunnels of termite mounds. We therefore predict that tools constructed from plant species known to be used as tool sources, would exhibit a lower EI than those constructed from plant species never sourced. Similar patterns of low EI are to be expected from plant species most preferred for tool construction than less preferred ones. Of those plant species that are known to be used for the manufacture of tools, some individual plants are used regularly by chimpanzees while others are ignored or used rarely.41 We predict these popular individual plants should produce tools of a lower EI than plants from the same species that have never been used. To test these predictions, we performed flexural rigidity tests on plant materials that are known to be used by chimpanzees in the construction of termite fishing tools and compared these to readily available but unused suitable plant material found close to termite mounds.

Pascual-Garrido, Alejandra; Carvalho, Susana; Mjungu, Deus; Schulz-Kornas, Ellen; van Casteren, Adam
Engineering skills in the manufacture of tools by wild chimpanzees
iScience (2025) DOI; 10.1016/j.isci.2025.112158.

Copyright: © 2025 The authors.
Published by Elsevier. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

So, we have yet another religious-based claim of human exceptionalism proving special creation exposed as bogus. What is cited by creationisst as evidence for secial creation has turned out, on examination by science, to be evidence for common descent and evolution.

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